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To establish whether items included in instruments published in the last decade assessing risk of bias of randomized controlled trials (RCTs) are indeed addressing risk of bias.We searched Medline, Embase, Web of Science, and Scopus from 2010 to October 2021 for instruments assessing risk of bias of RCTs. By extracting items and summarizing their essential content, we generated an item list. Items that two reviewers agreed clearly did not address risk of bias were excluded. We included the remaining items in a survey in which 13 experts judged the issue each item is addressing: risk of bias, applicability, random error, reporting quality, or none of the above.Seventeen eligible instruments included 127 unique items. After excluding 61 items deemed as clearly not addressing risk of bias, the item classification survey included 66 items, of which the majority of respondents deemed 20 items (30.3%) as addressing risk of bias; the majority deemed 11 (16.7%) as not addressing risk of bias; and there proved substantial disagreement for 35 (53.0%) items.Existing risk of bias instruments frequently include items that do not address risk of bias. For many items, experts disagree on whether or not they are addressing risk of bias.

Importance Extenuating circumstances can trigger unplanned changes to randomized trials and introduce methodological, ethical, feasibility, and analytical challenges that can potentially compromise the validity of findings. Numerous randomized trials have required changes in response to the COVID-19 pandemic, but guidance for reporting such modifications is incomplete. Objective As a joint extension for the CONSORT and SPIRIT reporting guidelines, CONSERVE (CONSORT and SPIRIT Extension for RCTs Revised in Extenuating Circumstances) aims to improve reporting of trial protocols and completed trials that undergo important modifications in response to extenuating circumstances. Evidence A panel of 37 international trial investigators, patient representatives, methodologists and statisticians, ethicists, funders, regulators, and journal editors convened to develop the guideline. The panel developed CONSERVE following an accelerated, iterative process between June 2020 and February 2021 involving (1) a rapid literature review of multiple databases (OVID Medline, OVID EMBASE, and EBSCO CINAHL) and gray literature sources from 2003 to March 2021; (2) consensus-based panelist meetings using a modified Delphi process and surveys; and (3) a global survey of trial stakeholders. Findings The rapid review yielded 41 673 citations, of which 38 titles were relevant, including emerging guidance from regulatory and funding agencies for managing the effects of the COVID-19 pandemic on trials. However, no generalizable guidance for all circumstances in which trials and trial protocols might face unanticipated modifications were identified. The CONSERVE panel used these findings to develop a consensus reporting guidelines following 4 rounds of meetings and surveys. Responses were received from 198 professionals from 34 countries, of whom 90% (n = 178) indicated that they understood the concept definitions and 85.4% (n = 169) indicated that they understood and could use the implementation tool. Feedback from survey respondents was used to finalize the guideline and confirm that the guideline’s core concepts were applicable and had utility for the trial community. CONSERVE incorporates an implementation tool and checklists tailored to trial reports and trial protocols for which extenuating circumstances have resulted in important modifications to the intended study procedures. The checklists include 4 sections capturing extenuating circumstances, important modifications, responsible parties, and interim data analyses. Conclusions and Relevance CONSERVE offers an extension to CONSORT and SPIRIT that could improve the transparency, quality, and completeness of reporting important modifications to trials in extenuating circumstances such as COVID-19.

Importance: The quality of reporting of randomized clinical trials is suboptimal. In an era in which the need for greater research transparency is paramount, inadequate reporting hinders assessment of the reliability and validity of trial findings. The Consolidated Standards of Reporting Trials (CONSORT) 2010 Statement was developed to improve the reporting of randomized clinical trials, but the primary focus was on parallel-group trials with 2 groups. Multi-arm trials that use a parallel-group design (comparing treatments by concurrently randomizing participants to one of the treatment groups, usually with equal probability) but have 3 or more groups are relatively common. The quality of reporting of multi-arm trials varies substantially, making judgments and interpretation difficult. While the majority of the elements of the CONSORT 2010 Statement apply equally to multi-arm trials, some elements need adaptation, and, in some cases, additional issues need to be clarified. Objective: To present an extension to the CONSORT 2010 Statement for reporting multi-arm trials to facilitate the reporting of such trials. Design: A guideline writing group, which included all authors, formed following the CONSORT group meeting in 2014. The authors met in person and by teleconference bimonthly between 2014 and 2018 to develop and revise the checklist and the accompanying text, with additional discussions by email. A draft manuscript was circulated to the wider CONSORT group of 36 individuals, plus 5 other selected individuals known for their specialist knowledge in clinical trials, for review. Extensive feedback was received from 14 individuals and, after detailed consideration of their comments, a final revised version of the extension was prepared. Findings: This CONSORT extension for multi-arm trials expands on 10 items of the CONSORT 2010 checklist and provides examples of good reporting and a rationale for the importance of each extension item. Key recommendations are that multi-arm trials should be identified as such and require clear objectives and hypotheses referring to all of the treatment groups. Primary treatment comparisons should be identified and authors should report the planned and unplanned comparisons resulting from multiple groups completely and transparently. If statistical adjustments for multiplicity are applied, the rationale and method used should be described. Conclusions and Relevance: This extension of the CONSORT 2010 Statement provides specific guidance for the reporting of multi-arm parallel-group randomized clinical trials and should help provide greater transparency and accuracy in the reporting of such trials.

The Consortium has produced these medical and service delivery guidelines about oral emergency contraceptive pills to assist family planning programs and providers in assuring that the women they serve can use these regimens effectively and safely. This document reflects the latest available evidence and has been reviewed by internationally recognized reproductive health experts. Local programs are welcome to adapt these guidelines as needed to comply with national or other requirements. These guidelines do not discuss the use of the copper-bearing intrauterine device for emergency contraception. This device is the most effective emergency contraceptive option and should be offered to women when appropriate. Some of the new research and data updated include: New details on the hormone UPA and new studies on the influence of BMI on effectiveness are briefly discussed as well as how ECP regimens work their efficacy and safety guidelines on repeat use and considerations for starting or resuming regular contraceptives following ECP regimens. This update includes a Clinical Summary document (https://www.cecinfo.org/wp-content/uploads/2018/12/18-209_ICEC-Clinical-Summary_121918.pdf) which highlights essential takeaways.

Random assignment of individual participants in clinical trials entails two steps: (i) generating an unbiased treatment allocation schedule; and (ii) applying the schedule without foreknowledge of upcoming allocations. These two steps were implicit in the famous randomized trial of streptomycin for pulmonary tuberculosis in 1948, and were recognized explicitly in some early books on controlled trials. However, half a century later, no widely accepted term denoting the process of concealing upcoming allocations had been adopted. In 1983 Thomas Chalmers and colleagues termed that process “randomization blinding,” and showed that blinded randomization and unblinded randomization were associated with differing estimates of treatment effects; however, their terminology was subsequently rarely used. In the mid-1990s we suggested that the term “allocation concealment” would be preferable to “blinded randomization,” particularly to avoid terminology that might be confused with blinding of treatments after random allocation. After controlling for more factors than had been accounted for by Chalmers and colleagues, we demonstrated an association between allocation concealment and estimates of treatment effects. Moreover, as further indication of bias, inadequately concealed trials displayed more heterogeneity than adequately concealed trials. Notably, our modeling and methodological approach to examine the associations between trial quality and estimates of treatment effects has gained recognition and achieved replication. A PubMed search for the term “allocation concealment” between 1972 and 1993 in “any field” yielded no instances, compared with 1471 between 1995 and 2016. Google Scholar found 25 matches before 1994 and over 30,000 matches after. Although the term might still be improved to avoid occasional misconceptions about its meaning, we assume that it has been widely adopted by authors and editors because they find the term useful.

Correctable weaknesses in the design, conduct, and analysis of biomedical and public health research studies can produce misleading results and waste valuable resources. Small effects can be difficult to distinguish from bias introduced by study design and analyses. An absence of detailed written protocols and poor documentation of research is common. Information obtained might not be useful or important, and statistical precision or power is often too low or used in a misleading way. Insufficient consideration might be given to both previous and continuing studies. Arbitrary choice of analyses and an overemphasis on random extremes might affect the reported findings. Several problems relate to the research workforce, including failure to involve experienced statisticians and methodologists, failure to train clinical researchers and laboratory scientists in research methods and design, and the involvement of stakeholders with conflicts of interest. Inadequate emphasis is placed on recording of research decisions and on reproducibility of research. Finally, reward systems incentivise quantity more than quality, and novelty more than reliability. We propose potential solutions for these problems, including improvements in protocols and documentation, consideration of evidence from studies in progress, standardisation of research efforts, optimisation and training of an experienced and non-conflicted scientific workforce, and reconsideration of scientific reward systems.

Background The Consolidated Standards of Reporting Trials (CONSORT) Statement is intended to facilitate better reporting of randomised clinical trials (RCTs). A systematic review recently published in the Cochrane Library assesses whether journal endorsement of CONSORT impacts the completeness of reporting of RCTs; those findings are summarised here. Methods Evaluations assessing the completeness of reporting of RCTs based on any of 27 outcomes formulated based on the 1996 or 2001 CONSORT checklists were included; two primary comparisons were evaluated. The 27 outcomes were: the 22 items of the 2001 CONSORT checklist, four sub-items describing blinding and a ‘total summary score’ of aggregate items, as reported. Relative risks (RR) and 99% confidence intervals were calculated to determine effect estimates for each outcome across evaluations. Results Fifty-three reports describing 50 evaluations of 16,604 RCTs were assessed for adherence to at least one of 27 outcomes. Sixty-nine of 81 meta-analyses show relative benefit from CONSORT endorsement on completeness of reporting. Between endorsing and non-endorsing journals, 25 outcomes are improved with CONSORT endorsement, five of these significantly (α = 0.01). The number of evaluations per meta-analysis was often low with substantial heterogeneity; validity was assessed as low or unclear for many evaluations. Conclusions The results of this review suggest that journal endorsement of CONSORT may benefit the completeness of reporting of RCTs they publish. No evidence suggests that endorsement hinders the completeness of RCT reporting. However, despite relative improvements when CONSORT is endorsed by journals, the completeness of reporting of trials remains sub-optimal. Journals are not sending a clear message about endorsement to authors submitting manuscripts for publication. As such, fidelity of endorsement as an ‘intervention’ has been weak to date. Journals need to take further action regarding their endorsement and implementation of CONSORT to facilitate accurate, transparent and complete reporting of trials.

Background An overwhelming body of evidence stating that the completeness of reporting of randomised controlled trials (RCTs) is not optimal has accrued over time. In the mid-1990s, in response to these concerns, an international group of clinical trialists, statisticians, epidemiologists, and biomedical journal editors developed the CONsolidated Standards Of Reporting Trials (CONSORT) Statement. The CONSORT Statement, most recently updated in March 2010, is an evidence-based minimum set of recommendations including a checklist and flow diagram for reporting RCTs and is intended to facilitate the complete and transparent reporting of trials and aid their critical appraisal and interpretation. In 2006, a systematic review of eight studies evaluating the "effectiveness of CONSORT in improving reporting quality in journals" was published. Objectives To update the earlier systematic review assessing whether journal endorsement of the 1996 and 2001 CONSORT checklists influences the completeness of reporting of RCTs published in medical journals. Search methods We conducted electronic searches, known item searching, and reference list scans to identify reports of evaluations assessing the completeness of reporting of RCTs. The electronic search strategy was developed in MEDLINE and tailored to EMBASE. We searched the Cochrane Methodology Register and the Cochrane Database of Systematic Reviews using the Wiley interface. We searched the Science Citation Index, Social Science Citation Index, and Arts and Humanities Citation Index through the ISI Web of Knowledge interface. We conducted all searches to identify reports published between January 2005 and March 2010, inclusive. Selection criteria In addition to studies identified in the original systematic review on this topic, comparative studies evaluating the completeness of reporting of RCTs in any of the following comparison groups were eligible for inclusion in this review: 1) Completeness of reporting of RCTs published in journals that have and have not endorsed the CONSORT Statement; 2) Completeness of reporting of RCTs published in CONSORT-endorsing journals before and after endorsement; or 3) Completeness of reporting of RCTs before and after the publication of the CONSORT Statement (1996 or 2001). We used a broad definition of CONSORT endorsement that includes any of the following: (a) requirement or recommendation in journal's 'Instructions to Authors' to follow CONSORT guidelines; (b) journal editorial statement endorsing the CONSORT Statement; or (c) editorial requirement for authors to submit a CONSORT checklist and/or flow diagram with their manuscript. We contacted authors of evaluations reporting data that could be included in any comparison group(s), but not presented as such in the published report and asked them to provide additional data in order to determine eligibility of their evaluation. Evaluations were not excluded due to language of publication or validity assessment. Data collection and analysis We completed screening and data extraction using standardised electronic forms, where conflicts, reasons for exclusion, and level of agreement were all automatically and centrally managed in web-based management software, DistillerSR®. One of two authors extracted general characteristics of included evaluations and all data were verified by a second author. Data describing completeness of reporting were extracted by one author using a pre-specified form; a 10% random sample of evaluations was verified by a second author. Any discrepancies were discussed by both authors; we made no modifications to the extracted data. Validity assessments of included evaluations were conducted by one author and independently verified by one of three authors. We resolved all conflicts by consensus. For each comparison we collected data on 27 outcomes: 22 items of the CONSORT 2001 checklist, plus four items relating to the reporting of blinding, and one item of aggregate CONSORT scores. Where reported, we extracted and qualitatively synthesised data on the methodological quality of RCTs, by scale or score. Main results Fifty-three publications reporting 50 evaluations were included. The total number of RCTs assessed within evaluations was 16,604 (median per evaluation 123 (interquartile range (IQR) 77 to 226) published in a median of six (IQR 3 to 26) journals. Characteristics of the included RCT populations were variable, resulting in heterogeneity between included evaluations. Validity assessments of included studies resulted in largely unclear judgements. The included evaluations are not RCTs and less than 8% (4/53) of the evaluations reported adjusting for potential confounding factors. Twenty-five of 27 outcomes assessing completeness of reporting in RCTs appeared to favour CONSORT-endorsing journals over non-endorsers, of which five were statistically significant. 'Allocation concealment' resulted in the largest effect, with risk ratio (RR) 1.81 (99% confidence interval (CI) 1.25 to 2.61), suggesting that 81% more RCTs published in CONSORT-endorsing journals adequately describe allocation concealment compared to those published in non-endorsing journals. Allocation concealment was reported adequately in 45% (393/876) of RCTs in CONSORT-endorsing journals and in 22% (329/1520) of RCTs in non-endorsing journals. Other outcomes with results that were significant include: scientific rationale and background in the 'Introduction' (RR 1.07, 99% CI 1.01 to 1.14); 'sample size' (RR 1.61, 99% CI 1.13 to 2.29); method used for 'sequence generation' (RR 1.59, 99% CI 1.38 to 1.84); and an aggregate score over reported CONSORT items, 'total sum score' (standardised mean difference (SMD) 0.68 (99% CI 0.38 to 0.98)). Authors' conclusions Evidence has accumulated to suggest that the reporting of RCTs remains sub-optimal. This review updates a previous systematic review of eight evaluations. The findings of this review are similar to those from the original review and demonstrate that, despite the general inadequacies of reporting of RCTs, journal endorsement of the CONSORT Statement may beneficially influence the completeness of reporting of trials published in medical journals. Future prospective studies are needed to explore the influence of the CONSORT Statement dependent on the extent of editorial policies to ensure adherence to CONSORT guidance.

The protocol of a clinical trial serves as the foundation for study planning, conduct, reporting, and appraisal. However, trial protocols and existing protocol guidelines vary greatly in content and quality. This article describes the systematic development and scope of SPIRIT (Standard Protocol Items: Recommendations for Interventional Trials) 2013, a guideline for the minimum content of a clinical trial protocol. The 33-item SPIRIT checklist applies to protocols for all clinical trials and focuses on content rather than format. The checklist recommends a full description of what is planned; it does not prescribe how to design or conduct a trial. By providing guidance for key content, the SPIRIT recommendations aim to facilitate the drafting of high-quality protocols. Adherence to SPIRIT would also enhance the transparency and completeness of trial protocols for the benefit of investigators, trial participants, patients, sponsors, funders, research ethics committees or institutional review boards, peer reviewers, journals, trial registries, policymakers, regulators, and other key stakeholders.

Background The CONsolidated Standards Of Reporting Trials (CONSORT) Statement provides a minimum standard set of items to be reported in published clinical trials; it has received widespread recognition within the biomedical publishing community. This research aims to provide an update on the endorsement of CONSORT by high impact medical journals. Methods We performed a cross-sectional examination of the online “Instructions to Authors” of 168 high impact factor (2012) biomedical journals between July and December 2014. We assessed whether the text of the “Instructions to Authors” mentioned the CONSORT Statement and any CONSORT extensions, and we quantified the extent and nature of the journals’ endorsements of these. These data were described by frequencies. We also determined whether journals mentioned trial registration and the International Committee of Medical Journal Editors (ICMJE; other than in regards to trial registration) and whether either of these was associated with CONSORT endorsement (relative risk and 95 % confidence interval). We compared our findings to the two previous iterations of this survey (in 2003 and 2007). We also identified the publishers of the included journals. Results Sixty-three percent (106/168) of the included journals mentioned CONSORT in their “Instructions to Authors.” Forty-four endorsers (42 %) explicitly stated that authors “must” use CONSORT to prepare their trial manuscript, 38 % required an accompanying completed CONSORT checklist as a condition of submission, and 39 % explicitly requested the inclusion of a flow diagram with the submission. CONSORT extensions were endorsed by very few journals. One hundred and thirty journals (77 %) mentioned ICMJE, and 106 (63 %) mentioned trial registration. Conclusions The endorsement of CONSORT by high impact journals has increased over time; however, specific instructions on how CONSORT should be used by authors are inconsistent across journals and publishers. Publishers and journals should encourage authors to use CONSORT and set clear expectations for authors about compliance with CONSORT.

Supplementary Material Supplementary appendix Download Summary This Review is intended to help clinicians, patients, and the public make informed decisions about statin therapy for the prevention of heart attacks and strokes. It explains how the evidence that is available from randomised controlled trials yields reliable information about both the efficacy and safety of statin therapy. In addition, it discusses how claims that statins commonly cause adverse effects reflect a failure to recognise the limitations of other sources of evidence about the effects of treatment. Large-scale evidence from randomised trials shows that statin therapy reduces the risk of major vascular events (ie, coronary deaths or myocardial infarctions, strokes, and coronary revascularisation procedures) by about one-quarter for each mmol/L reduction in LDL cholesterol during each year (after the first) that it continues to be taken. The absolute benefits of statin therapy depend on an individual's absolute risk of occlusive vascular events and the absolute reduction in LDL cholesterol that is achieved. For example, lowering LDL cholesterol by 2 mmol/L (77 mg/dL) with an effective low-cost statin regimen (eg, atorvastatin 40 mg daily, costing about £2 per month) for 5 years in 10 000 patients would typically prevent major vascular events from occurring in about 1000 patients (ie, 10% absolute benefit) with pre-existing occlusive vascular disease (secondary prevention) and in 500 patients (ie, 5% absolute benefit) who are at increased risk but have not yet had a vascular event (primary prevention). Statin therapy has been shown to reduce vascular disease risk during each year it continues to be taken, so larger absolute benefits would accrue with more prolonged therapy, and these benefits persist long term. The only serious adverse events that have been shown to be caused by long-term statin therapy—ie, adverse effects of the statin—are myopathy (defined as muscle pain or weakness combined with large increases in blood concentrations of creatine kinase), new-onset diabetes mellitus, and, probably, haemorrhagic stroke. Typically, treatment of 10 000 patients for 5 years with an effective regimen (eg, atorvastatin 40 mg daily) would cause about 5 cases of myopathy (one of which might progress, if the statin therapy is not stopped, to the more severe condition of rhabdomyolysis), 50–100 new cases of diabetes, and 5–10 haemorrhagic strokes. However, any adverse impact of these side-effects on major vascular events has already been taken into account in the estimates of the absolute benefits. Statin therapy may cause symptomatic adverse events (eg, muscle pain or weakness) in up to about 50–100 patients (ie, 0·5–1·0% absolute harm) per 10 000 treated for 5 years. However, placebo-controlled randomised trials have shown definitively that almost all of the symptomatic adverse events that are attributed to statin therapy in routine practice are not actually caused by it (ie, they represent misattribution). The large-scale evidence available from randomised trials also indicates that it is unlikely that large absolute excesses in other serious adverse events still await discovery. Consequently, any further findings that emerge about the effects of statin therapy would not be expected to alter materially the balance of benefits and harms. It is, therefore, of concern that exaggerated claims about side-effect rates with statin therapy may be responsible for its under-use among individuals at increased risk of cardiovascular events. For, whereas the rare cases of myopathy and any muscle-related symptoms that are attributed to statin therapy generally resolve rapidly when treatment is stopped, the heart attacks or strokes that may occur if statin therapy is stopped unnecessarily can be devastating.

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The Revised CONSORT Statement for Reporting Randomized Trials: Explanation and Elaboration (2001) (continuation).

Objective: To examine whether the association of inadequate or unclear allocation concealment and lack of blinding with biased estimates of intervention effects varies with the nature of the intervention or outcome. Design: Combined analysis of data from three metaepidemiological studies based on collections of metaanalyses. Data sources 146 meta-analyses including 1346 trials examining a wide range of interventions and outcomes. Main outcome measures Ratios of odds ratios quantifying the degree of bias associated with inadequate or unclear allocation concealment, and lack of blinding, for trials with different types of intervention and outcome. A ratio of odds ratios

Die reiche Geschichte der Verblindung erstreckt sich uber zwei Jahrhunderte. Weltweit wissen die meisten Wissenschaftler, was mit Verblindung gemeint ist, doch hinter einem nur allgemeinen Verstandnis lauert oftmals Verwirrung. Begriffe wie einfachblind, doppelblind und dreifachblind haben fur verschiedene Personen unterschiedliche Bedeutung. Auserdem verwechseln viele medizinische Forscher die Verblindung mit der Geheimhaltung der Randomisierungsliste. Solche Verwechslungen zeigen, dass beide Begriffe missverstanden werden. Verblindung bedeutet, das Studienteilnehmer, Studienarzte (meist diejenigen, die die Behandlung verabreichen) oder Bewerter (diejenigen, die die Outcome-Daten erheben) die zugeteilte Intervention nicht kennen, sodass sie durch dieses Wissen nicht beeinflusst werden. Im Allgemeinen fuhrt die Verblindung zu einem Ruckgang der unterschiedlichen Bewertung von Behandlungsergebnissen (Informationsbias). Sie kann bei den Studienteilnehmern aber auch die Compliance und die Bereitschaft zum Verbleib in der Studie verbessern, wahrend sie die Anwendung zusatzlicher Pflege- oder Therapiemasnahmen (manchmal als Ko-Intervention bezeichnet) reduziert. Studienarzte und Leser gehen vielfach gutglaubig davon aus, dass eine randomisierte Studie einfach dann als hochwertig anzusehen ist, wenn sie doppelt verblindet wurde, als ob es sich bei der doppelten Verblindung um die Conditio sine qua non einer randomisierten, kontrollierten Studie handelte. Auch wenn die Doppelverblindung (Verblindung von Studienarzten, Studienteilnehmern und Bewertern der Behandlungsergebnisse) auf eine solide Studienplanung schliesen lasst, durfen Studien ohne Doppelverblindung nicht automatisch als minderwertig eingestuft werden. Anstatt sich ausschlieslich auf Begriffe wie Doppelverblindung zu verlassen, sollten Wissenschaftler explizit angeben, wer wie verblindet wurde. Wir empfehlen, den Ergebnissen mehr Glauben zu schenken, wenn zumindest die Bewertung der Studienergebnisse verblindet erfolgte, mit Ausnahme von objektiven Endpunkten wie etwa der Mortalitat, die kaum Raum fur systematische Fehler (Bias) lassen. Wenn Studienarzte ihre Verblindungsmasnahmen korrekt angeben, kann der Leser sie beurteilen. Leider lasst die Berichterstattung in vielen Artikeln zu wunschen ubrig. Wenn in einem Beitrag behauptet wird, es habe eine Verblindung stattgefunden, ohne dies weiter zu erklaren, sollte der Leser hinsichtlich ihrer Bias reduzierenden Wirkung skeptisch bleiben.

Korrekte Randomisierung beruht auf einer angemessenen Geheimhaltung der Randomisierungsliste. Die Geheimhaltung sorgt dafur, dass Arzte und Studienteilnehmer die nachfolgenden Zuteilungen nicht kennen. Ohne Geheimhaltung konnen auch korrekt erstellte Randomisierungslisten ausgehebelt werden. Dabei geht die so wichtige Eigenschaft der Verzerrungsfreiheit randomisierter, kontrollierter Studien mit hochst argerlichen Implementierungsproblemen einher. Haufig steht eine angemessene Geheimhaltung arztlichen Neigungen entgegen, was bei denen, die Studien durchfuhren, zu Verdruss fuhrt. Randomisierte, kontrollierte Studien sind Arzten ein Grauel. Viele, die an Studien teilnehmen, kommen in Versuchung, die Zuteilungen zu entschlusseln, und unterlaufen dadurch die Randomisierung. Fur manche Studienarzte stellt die Entschlusselung des Zuteilungsschemas eine viel zu grose intellektuelle Herausforderung dar, als dass sie ihr widerstehen konnten. Ob ihre Motive nun harmloser oder boshafter Natur sind, in jedem Fall untergraben derlei Manipulationen die Validitat einer Studie. Tatsachlich fuhrt eine unzureichende Geheimhaltung im Durchschnitt zu ubertriebenen Effektschatzern, doch mit Raum fur Bias in beide Richtungen. Studienarzte sind in ihren Bemuhungen um die Entschlusselung von Zuteilungslisten sehr erfinderisch, sodass Studienplaner bei ihren Planungsanstrengungen ebenso geschickt vorgehen mussen, um dies zu verhindern. Sie mussen ihre Studien durch eine angemessene Geheimhaltung der Behandlungszuteilung wirksam vor Selektionsbias und Confounding schutzen. Vergleiche der Ausgangscharakteristika zu wichtigen prognostischen Variablen sollten angegeben werden. Hypothesentests fur Ausgangscharakteristika sind dagegen uberflussig und konnten sogar Schaden anrichten, wenn sie Studienleiter dazu verleiten, Unausgewogenheiten hinsichtlich der Ausgangscharakteristika zu verschweigen. „Der Grund dafur, warum die kontrollierte Studie des Medical Research Council uber Streptomycin zur Behandlung von Lungentuberkulose als Meilenstein betrachtet werden sollte, ist nicht, wie haufig vermutet wird, dass zur Generierung der Randomisierungsliste Zufallszahlentabellen verwendet wurden. … Der Grund sind vielmehr die eindeutig beschriebenen Vorsichtsmasnahmen, die ergriffen wurden, um die Randomisierungsliste vor den an der Rekrutierung der Patienten beteiligten Personen geheim zu halten [1] .“

Die randomisierte kontrollierte Studie ist zwar der Goldstandard der klinischen Forschung, doch ist die Randomisierung nach wie vor der dabei vermutlich am wenigsten verstandene Aspekt. Dabei fuhren Defizite bei der Randomisierung zu Selektionsbias und Storeffekten (Confounding). Wissenschaftler sollten einen weiten Bogen um alle systematischen, nicht-zufalligen Zuteilungsverfahren machen. Die Studienteilnehmer sollten den Vergleichsgruppen auf der Grundlage von Zufallsverfahren zugeteilt werden. Die elementarste der verschiedenen Methoden zur Generierung einer Randomisierungsliste ist die einfache (uneingeschrankte) Randomisierung, die dem wiederholten fairen Munzwurf vergleichbar ist. Zudem wird die einfache Randomisierung, was die Vermeidung von systematischen Fehlern (Bias) anbelangt, von keinem anderen Verfahren ubertroffen, und sei es auch noch so komplex und ausgeklugelt. Studienleiter sollten diese Methode deshalb haufiger anwenden als bisher, und der Leser sollte ungleiche Gruppengrosen erwarten und akzeptieren. Etliche andere komplizierte Verfahren der eingeschrankten Randomisierung begrenzen die Wahrscheinlichkeit unerwunschter Fallzahlunterschiede in den Interventionsgruppen. Das am haufigsten zur eingeschrankten Randomisierung angewendete Verfahren ist die Blockrandomisierung. Bei Anwendung dieses Verfahrens sollten Blockgrosen nach dem Zufallsprinzip variiert und grosere Blocklangen gewahlt werden; dies gilt vor allem fur unverblindete Studien. Weitere eingeschrankte Verfahren wie die Urnenrandomisierung vereinen die vorteilhaften Eigenschaften der einfachen mit denen der eingeschrankten Randomisierung, indem sie die Unvorhersagbarkeit zwar grostenteils bewahren, gleichzeitig aber auch ein gewisses Gleichgewicht herstellen. Die Wirksamkeit der geschichteten Randomisierung hangt davon ab, dass man ein eingeschranktes Randomisierungsverfahren verwendet, um die Gruppenzuteilung in den einzelnen Schichten (Strata) zu balancieren. Die Generierung einer angemessenen Randomisierungsliste kostet nur wenig Zeit und Muhe; der Lohn sind wissenschaftliche Genauigkeit und Glaubwurdigkeit. Untersucher sollten entsprechende Ressourcen fur die Generierung adaquat randomisierter Studien bereitstellen und ihre Methoden eindeutig darlegen.

Surrogate end points in clinical research pose real danger. A surrogate end point is an outcome measure, commonly a laboratory test, that substitutes for a clinical event of true importance. Resistance to activated protein C, for example, has been used as a surrogate for venous thrombosis in women using oral contraceptives. Other examples of inappropriate surrogate end points in contraception include the postcoital test instead of pregnancy to evaluate new spermicides, breakage and slippage instead of pregnancy to evaluate condoms, and bone mineral density instead of fracture to assess the safety of depo-medroxyprogesterone acetate. None of these markers captures the effect of the treatment on the true outcome. A valid surrogate end point must both correlate with and accurately predict the outcome of interest. Although many surrogate markers correlate with an outcome, few have been shown to capture the effect of a treatment (for example, oral contraceptives) on the outcome (venous thrombosis). As a result, thousands of useless and misleading reports on surrogate end points litter the medical literature. New drugs have been shown to benefit a surrogate marker, but, paradoxically, triple the risk of death. Thousands of patients have died needlessly because of reliance on invalid surrogate markers. Researchers should avoid surrogate end points unless they have been validated; that requires at least one well done trial using both the surrogate and true outcome. The clinical maxim that "a difference to be a difference must make a difference" applies to research as well. Clinical research should focus on outcomes that matter.

Likelihood ratios can refine clinical diagnosis on the basis of signs and symptoms; however, they are underused for patients' care. A likelihood ratio is the percentage of ill people with a given test result divided by the percentage of well individuals with the same result. Ideally, abnormal test results should be much more typical in ill individuals than in those who are well (high likelihood ratio) and normal test results should be most frequent in well people than in sick people (low likelihood ratio). Likelihood ratios near unity have little effect on decision-making; by contrast, high or low ratios can greatly shift the clinician's estimate of the probability of disease. Likelihood ratios can be calculated not only for dichotomous (positive or negative) tests but also for tests with multiple levels of results, such as creatine kinase or ventilation-perfusion scans. When combined with an accurate clinical diagnosis, likelihood ratios from ancillary tests improve diagnostic accuracy in a synergistic manner.

Summary Investigators should properly calculate sample sizes before the start of their randomised trials and adequately describe the details in their published report. In these a-priori calculations, determining the effect size to detect—eg, event rates in treatment and control groups—reflects inherently subjective clinical judgments. Furthermore, these judgments greatly affect sample size calculations. We question the branding of trials as unethical on the basis of an imprecise sample size calculation process. So-called underpowered trials might be acceptable if investigators use methodological rigor to eliminate bias, properly report to avoid misinterpretation, and always publish results to avert publication bias. Some shift of emphasis from a fixation on sample size to a focus on methodological quality would yield more trials with less bias. Unbiased trials with imprecise results trump no results at all. Clinicians and patients deserve guidance now.

Use of control (comparison) groups is a powerful research tool. In case-control studies, controls estimate the frequency of an exposure in the population under study. Controls can be taken from known or unknown study populations. A known group consists of a defined population observed over a period, such as passengers on a cruise ship. When the study group is known, a sample of the population can be used as controls. If no population roster exists, then techniques such as random-digit dialling can be used. Sometimes, however, the study group is unknown, for example, motor-vehicle crash victims brought to an emergency department, who may come from far away. In this situation, hospital controls, neighbourhood controls, and friend, associate, or relative controls can be used. In general, one well-selected control group is better than two or more. When the number of cases is small, the ratio of controls to cases can be raised to improve the ability to find important differences. Although no ideal control group exists, readers need to think carefully about how representative the controls are. Poor choice of controls can lead to both wrong results and possible medical harm.

Concern about estrogen-related adverse effects has led to progressive reductions in the estrogen dose in combination oral contraceptives (COCs). This review of randomized controlled trials tested the hypothesis that COCs containingor=20 microg ethinyl estradiol (EE) perform similarly to those containing20 microg in terms of contraceptive effectiveness, bleeding patterns, discontinuation and side effects. Data from the 18 eligible trials conducted to date are inadequate for detecting possible differences in contraceptive effectiveness. Several COCs containing 20 microg EE resulted in higher rates of early trial discontinuation (overall and due to adverse events such as irregular bleeding) as well as increased risk of bleeding disturbances (both amenorrhea/infrequent bleeding and irregular, prolonged, frequent bleeding or breakthrough bleeding or spotting) than their higher-estrogen comparison pills. However, most trials compared COCs containing different progestin types, and changes in bleeding patterns could be related to progestin type as well as estrogen dose. While health care providers and women might select COCs containing 20 microg EE based on theoretical improvements in safety profile from the reduced dose of estrogen, no evidence is available to support this choice.

To comprehend the result of a randomized controlled trial (RCT), readers must understand its design, conduct, analysis and interpretation. That goal can be achieved only through complete transparency from authors. Despite several decades of educational efforts, the reporting of RCTs needs improvement. Investigators and editors developed the original CONSORT (Consolidated Standards of Reporting Trials) statement to help authors improve reporting by using a checklist and flow diagram. The revised CONSORT statement presented in this article incorporates new evidence and addresses some criticism of the original statement. The checklist items pertain to the content of the Title, Abstract, Introduction, Methods, Results, and Comment. The revised checklist includes 22 items selected because empirical evidence indicates that not reporting the information is associated with biased estimates of treatment effect or because the information is essential to judge the reliability or relevance of the findings. We intended the flow diagram to depict the passage or participants through an RCT. The revised flow diagram depicts information from 4 stages of a trial (enrollment, intervention allocation, follow-up and analysis). The diagram explicitly includes the number of participants, according to each intervention group, included in the primary data analysis. Inclusion of these numbers allows the reader to judge whether the authors have performed an intention-to-treat analysis. In sum, the CONSORT statement is intended to improve the reporting or an RCT, enabling readers to understand a trial's conduct and to assess the validity of its results.

Objective Many women and clinicians believe that combination estrogen-progestin contraceptive use can lead to weight gain. This concern can deter women from starting hormonal contraception or lead to premature quitting. This review evaluated the association between combination contraceptive use and change in body weight. Data sources The computerized databases CENTRAL, MEDLINE, EMBASE, Popline, and LILACS (from their inception to 2002) were used to conduct this review. Known investigators and manufacturers were contacted for information about other trials not discovered in the database search. Methods of study selection All English-language, randomized controlled trials measuring weight change that were at least 3 treatment cycles in duration and that compared a combination contraceptive to a placebo or to a combination contraceptive that differed in drug, dosage, regimen, or study length were eligible for inclusion. Of the 570 reports of randomized controlled trials of eligible interventions that were identified, 42 trials were included in the systematic review. Tabulation, integration, and results Two reviewers independently abstracted data from the eligible trials using a standard form. Depending on the data available, the weighted mean difference using a fixed effect model with 95% confidence intervals was calculated for the mean change in weight between baseline and posttreatment measurements or the Peto odds ratio with 95% confidence intervals was calculated by using the proportion of women who gained or lost more than a specified amount of weight. The 3 placebo-controlled, randomized trials did not find evidence supporting a causal association between combination oral contraceptives or a combination skin patch and weight gain. Most comparisons from the 40 trials that compared 2 or more combination contraceptives showed no substantial difference in weight. In addition, discontinuation of combination contraceptives because of weight gain did not differ between groups when this factor was studied. Conclusion Available evidence is insufficient to determine the effect of combination contraceptives on weight, but no large effect is evident.

Contraception choices may be limited for lactating women due to concerns about hormonal effects on quality and quantity of milk, passage of hormones to the infant and infant growth. We conducted a systematic review of randomized controlled trials to determine the effect of hormonal contraception on lactation. We sought all randomized controlled trials, reported in any language, that included any form of hormonal contraception compared with another form of hormonal contraception, nonhormonal contraception or placebo during lactation. Seven reports from five randomized controlled trials met the inclusion criteria. Most of the five trials did not specify their method used to generate a random sequence, method of allocation concealment, blinding of treatments or use of an intention-to-treat analysis. Additionally, high loss-to-follow-up rates invalidated at least two trials. The findings from two trials comparing oral contraceptives to placebo during lactation were conflicting. Another trial found no inhibitory effects on lactation from progestin-only contraceptives. Finally, the World Health Organization trial found a statistically significant decline in breast milk volume in women using combined oral contraceptives compared to women using progestin-only pills. However, infant growth for the two groups did not differ. The limited evidence from randomized controlled trials on the effect of hormonal contraceptives during lactation is of poor quality and insufficient to establish an effect of hormonal contraception, if any, on milk quality and quantity. At least one properly conducted randomized controlled trial of adequate size is urgently needed to make recommendations regarding hormonal contraceptive use for lactating women.

The contraceptive vaginal sponge was developed as an alternative to the contraceptive diaphragm. Unlike the diaphragm, the sponge can be used for more than one coital act within 24 h without the insertion of additional spermicide, and it does not require fitting or a prescription from a physician. We conducted a systematic review of randomized controlled trials that compared the vaginal contraceptive sponge with the diaphragm used with a spermicide in order to evaluate the efficacy and continuation rates of the two devices. The sponge was statistically significantly less effective in preventing overall pregnancy than was the diaphragm in the two trials that met our inclusion criteria. The 12-month cumulative life table termination rates per 100 women for overall pregnancy were 17.4 for the sponge versus 12.8 for the diaphragm in the larger US trial, and 24.5 for the sponge and 10.9 for the diaphragm in the UK trial. Similarly, discontinuation rates at 12 months were higher with the sponge than with the diaphragm [odds ratio 1.3; 95% confidence interval (CI) 1.1-1.6]. Allergic-type reactions were more common with the sponge in both trials, although the frequency of discontinuation for discomfort differed in the two trials. Other randomized controlled trials will be needed to resolve the role of spermicides in preventing sexually transmitted infections or in causing adverse effects.

In the early 1800s, Karl Baedeker, a German publisher, launched a series of travel guidebooks. By the twentieth century, the guidebooks had achieved such international fame that his name became synonymous with the genre. As clinicians wade into the flood of clinical research being published, a guidebook can be a handy navigational aid. In this article, we offer a Baedeker for reading the literature, an approach distilled from our three decades of clinical practice and research experience. Interested readers can find more detail in our recent series on research methods in The Lancet (1–11). Reading research is mandatory if a clinician is to keep up. With greater age and experience, clinical practice should improve. Paradoxically, however, greater age and clinical experience often translate into rusty practice. As has been shown for treatment of hypertension, one of the strongest determinants of appropriate practice is number of years since medical school graduation; stated alternatively, practice quality deteriorates over time (12, 13). Keeping current is difficult after leaving formal training, and that difficulty may be greater for those who practice in smaller communities (14). If one cannot (or chooses not to) read, then one’s practice is condemned to becoming obsolete. This indirectly hurts patients. A second benefit of critical reading of clinical research is appropriate adoption (or rejection) of new technologies. Obstetrics and gynecology has a long, blemished record of adoption and dissemination of new tests and procedures without evidence of benefit (15). Episiotomy, one of the most common operations performed on adults in the last century, swept into practice based on DeLee’s analogy that childbirth is tantamount to impalement on a pitchfork (16). Urinary estriol measurement to monitor a fetus thought to be in jeopardy has been replaced by an even more expensive and cumbersome test (nonstress testing) for which no evidence of benefit exists either (17). Electronic fetal monitoring took U.S. obstetrics by storm in the absence of demonstrable benefit; a quarter century of study has failed to show any lasting benefit to babies (18), and the poor predictive value of worrisome tracings has needlessly driven up the cesarean delivery rate. Liquid-based cervical cytology screening has not been shown to reduce cervical cancer incidence or mortality, and the cost per case of cancer detected is higher with this approach than with conventional cytology (19). Ironically, poor women at highest risk of this cancer may not be able to afford the screening (20). Reports of new laparoscopy operations have recently been retracted by an editor, because the reported information could not be corroborated (21, 22). This hurt patients as well. While reading clinical research is clearly important, the task is daunting. First, the volume being published is overwhelming, with an estimated 25,000 biomedical journals in print. One challenge is picking and choosing what to read. In general, most readers should limit themselves to articles that are both relevant to their practices and likely to be of high scientific value. These two criteria will immediately narrow the field. Once an article is selected, another problem emerges: many clinicians in obstetrics and gynecology report that they cannot critically read the literature (23). Our graduates leave their training full of the Correspondence to: Family Health International, P.O. Box 13950, Research Triangle Park, NC 27709. Email: dgrimes@fhi.org

Biases in systematic reviews and meta-analyses may be examined in 'meta-epidemiological' studies, in which the influence of trial characteristics such as measures of study quality on treatment effect estimates is explored. Published studies to date have analysed data from collections of meta-analyses with binary outcomes, using logistic regression models that assume that there is no between- or within-meta-analysis heterogeneity. Using data from a study of publication bias (39 meta-analyses, 394 published and 88 unpublished trials) and language bias (29 meta-analyses, 297 English language trials and 52 non-English language trials), we compare results from logistic regression models, with and without robust standard errors to allow for clustering on meta-analysis, with results using a 'meta-meta-analytic' approach that can allow for between- and within-meta-analysis heterogeneity. We also consider how to allow for the confounding effects of different trial characteristics. We show that both within- and between meta-analysis heterogeneity may be of importance in the analysis of meta-epidemiological studies, and that confounding exists between the effects of publication status and trial quality.

Summary Proper randomisation means little if investigators cannot include all randomised participants in the primary analysis. Participants might ignore follow-up, leave town, or take aspartame when instructed to take aspirin. Exclusions before randomisation do not bias the treatment comparison, but they can hurt generalisability. Eligibility criteria for a trial should be clear, specific, and applied before randomisation. Readers should assess whether any of the criteria make the trial sample atypical or unrepresentative of the people in which they are interested. In principle, assessment of exclusions after randomisation is simple: none are allowed. For the primary analysis, all participants enrolled should be included and analysed as part of the original group assigned (an intent-to-treat analysis). In reality, however, losses frequently occur. Investigators should, therefore, commit adequate resources to develop and implement procedures to maximise retention of participants. Moreover, researchers should provide clear, explicit information on the progress of all randomised participants through the trial by use of, for instance, a trial profile. Investigators can also do secondary analyses on, for instance, per-protocol or as-treated participants. Such analyses should be described as secondary and non-randomised comparisons. Mishandling of exclusions causes serious methodological difficulties. Unfortunately, some explanations for mishandling exclusions intuitively appeal to readers, disguising the seriousness of the issues. Creative mismanagement of exclusions can undermine trial validity.

Summary Epidemiologists benefit greatly from having case-control study designs in their research armamentarium. Case-control studies can yield important scientific findings with relatively little time, money, and effort compared with other study designs. This seemingly quick road to research results entices many newly trained epidemiologists. Indeed, investigators implement case-control studies more frequently than any other analytical epidemiological study. Unfortunately, case-control designs also tend to be more susceptible to biases than other comparative studies. Although easier to do, they are also easier to do wrong. Five main notions guide investigators who do, or readers who assess, case-control studies. First, investigators must explicitly define the criteria for diagnosis of a case and any eligibility criteria used for selection. Second, controls should come from the same population as the cases, and their selection should be independent of the exposures of interest. Third, investigators should blind the data gatherers to the case or control status of participants or, if impossible, at least blind them to the main hypothesis of the study. Fourth, data gatherers need to be thoroughly trained to elicit exposure in a similar manner from cases and controls; they should use memory aids to facilitate and balance recall between cases and controls. Finally, investigators should address confounding in case-control studies, either in the design stage or with analytical techniques. Devotion of meticulous attention to these points enhances the validity of the results and bolsters the reader's confidence in the findings.

Summary The randomised controlled trial sets the gold standard of clinical research. However, randomisation persists as perhaps the least-understood aspect of a trial. Moreover, anything short of proper randomisation courts selection and confounding biases. Researchers should spurn all systematic, non-random methods of allocation. Trial participants should be assigned to comparison groups based on a random process. Simple (unrestricted) randomisation, analogous to repeated fair coin-tossing, is the most basic of sequence generation approaches. Furthermore, no other approach, irrespective of its complexity and sophistication, surpasses simple randomisation for prevention of bias. Investigators should, therefore, use this method more often than they do, and readers should expect and accept disparities in group sizes. Several other complicated restricted randomisation procedures limit the likelihood of undesirable sample size imbalances in the intervention groups. The most frequently used restricted sequence generation procedure is blocked randomisation. If this method is used, investigators should randomly vary the block sizes and use larger block sizes, particularly in an unblinded trial. Other restricted procedures, such as urn randomisation, combine beneficial attributes of simple and restricted randomisation by preserving most of the unpredictability while achieving some balance. The effectiveness of stratified randomisation depends on use of a restricted randomisation approach to balance the allocation sequences for each stratum. Generation of a proper randomisation sequence takes little time and effort but affords big rewards in scientific accuracy and credibility. Investigators should devote appropriate resources to the generation of properly randomised trials and reporting their methods clearly.

The outcomes reported for trials often differ from those specified in the protocol. Douglas Altman , David Moher , and Kenneth Schulz call for journals to do more to ensure that authors follow guidelines