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International audience; We investigated mechanisms of the false-positive test results on rapid-antigen detection test (RADT) for group A Streptococcal (GAS) pharyngitis. Most RADT false-positives (76%) were associated with polymerase chain reaction-positive GAS results, suggesting that RADT specificity could be considered close to 100%. Finding that 61% of GAS culture-negative but RADT-positive cases were positive on both GAS polymerase chain reaction and Staphylococcus aureus testing, we posit bacterial inhibition as causative.

International audience; We aimed to assess the independent effect of clinical spectrum, bacterial inoculum size and physician characteristics on the sensitivity of a rapid antigen detection test (RADT) for group A streptococcus (GAS) in children. Double throat swabs were collected from 1,482 children with pharyngitis and 294 asymptomatic children in a French prospective, office-based, multicenter (n = 17) study, from October 2009 to May 2011. Patient- and physician-level factors potentially affecting RADT sensitivity were studied by univariate and multivariate multilevel analysis, with laboratory throat culture as the reference test. In children with pharyngitis and asymptomatic children, the prevalence of GAS was 38 % (95 % confidence interval 36-41 %) and 11 % (7-14 %), respectively. Overall, RADT sensitivity was 87 % (84-90 %). On stratified and multivariate multilevel analysis, RADT sensitivity was higher for children with pharyngitis than asymptomatic children (89 % vs. 41 %), children 99 %). The sensitivity of the RADT is independently affected by patient- and physician-level factors. Physicians who base their diagnosis of GAS pharyngitis on the results of a RADT alone should consider diagnostic accuracy monitoring and adequate training when needed.

Background The stability of the accuracy of a diagnostic test is critical to whether clinicians can rely on its result. We aimed to assess whether the performance of a rapid antigen detection test (RADT) for group A streptococcus (GAS) is affected by the clinical spectrum and/or bacterial inoculum size. Methods Throat swabs were collected from 785 children with pharyngitis in an office-based, prospective, multicenter study (2009–2010). We analysed the effect of clinical spectrum (i.e., the McIsaac score and its components) and inoculum size (light or heavy GAS growth) on the accuracy (sensitivity, specificity, likelihood ratios and predictive values) of a RADT, with laboratory throat culture as the reference test. We also evaluated the accuracy of a McIsaac-score–based decision rule. Results GAS prevalence was 36% (95CI: 33%–40%). The inoculum was heavy for 85% of cases (81%–89%). We found a significant spectrum effect on sensitivity, specificity, likelihood ratios and positive predictive value (p

Importance Conference abstracts present information that helps clinicians and researchers to decide whether to attend a presentation. They also provide a source of unpublished research that could potentially be included in systematic reviews. We systematically assessed whether conference abstracts of studies that evaluated the accuracy of a diagnostic test were sufficiently informative. Observations We identified all abstracts describing work presented at the 2010 Annual Meeting of the Association for Research in Vision and Ophthalmology. Abstracts were eligible if they included a measure of diagnostic accuracy, such as sensitivity, specificity, or likelihood ratios. Two independent reviewers evaluated each abstract using a list of 21 items, selected from published guidance for adequate reporting. A total of 126 of 6310 abstracts presented were eligible. Only a minority reported inclusion criteria (5%), clinical setting (24%), patient sampling (10%), reference standard (48%), whether test readers were masked (7%), 2 × 2 tables (16%), and confidence intervals around accuracy estimates (16%). The mean number of items reported was 8.9 of 21 (SD, 2.1; range, 4-17). Conclusions and Relevance Crucial information about study methods and results is often missing in abstracts of diagnostic studies presented at the Association for Research in Vision and Ophthalmology Annual Meeting, making it difficult to assess risk for bias and applicability to specific clinical settings.

OBJECTIVES: Informative journal abstracts are crucial for the identification and initial appraisal of studies. We aimed to evaluate the informativeness of abstracts of diagnostic accuracy studies. STUDY DESIGN AND SETTING: PubMed was searched for reports of studies that had evaluated the diagnostic accuracy of a test against a clinical reference standard, published in 12 high-impact journals in 2012. Two reviewers independently evaluated the information contained in included abstracts using 21 items deemed important based on published guidance for adequate reporting and study quality assessment. RESULTS: We included 103 abstracts. Crucial information on study population, setting, patient sampling, and blinding as well as confidence intervals around accuracy estimates were reported in

Objectifs Realiser une validation externe des regles de decision clinique (RDC) pour le diagnostic des angines a streptocoque du groupe A (SGA). Sujet / materiels et methodes Les 8 RDC identifiees grâce a une revue systematique ont ete appliquees aux donnees d’une cohorte prospective de 676 enfants avec angine de la maniere suivante : faible risque de SGA d’apres la RDC, pas de test de diagnostic rapide (TDR) ni d’antibiotique ; risque intermediaire, antibiotherapie selon le resultat d’un TDR ; haut risque, antibiotherapie empirique. Le test de reference etait la culture de prelevement de gorge. Les donnees manquantes ont ete gerees par imputation multiple. Resultats principaux La calibration des RDC etait faible et aucune RDC n’etait capable de rejeter ou de confirmer le diagnostic de SGA (risque de SGA rho =0,94 ; p Conclusions Les RDC disponibles pour selectionner les enfants chez qui realiser un TDR ne sont pas suffisamment bien calibrees ni performantes pour pouvoir etre recommandees en pratique clinique.

Introduction Depuis 1992, le reseau Francais d’etude genetique de la sclerose en plaques recrute au niveau national des patients affectes par la sclerose en plaques et leur famille. La collection regroupe a ce jour environ 800 patients. Objectifs Nous avons decrit la cohorte d’un point de vue clinique afin d’en evaluer la representativite et de mettre en evidence un biais de recrutement potentiel. Une etude analytique de l’effet dose du locus HLA a ete realisee. Methodes La collection d’ADN est stockee et geree au sein de l’UMR S 546 et a fait l’objet d’une labellisation en « Centre de Ressources Biologiques » par l’INSERM et le Ministere de la Recherche en 2002. A ce jour, 557 familles simplex et 115 familles multiplex sont disponibles pour les etudes genetiques. A chaque prelevement, les criteres cliniques comme l’âge de debut de la maladie, le mode d’evolution et le degre de handicap (EDSS) sont recueillis. Un typage HLA (locus HLA DR) est realise sur chaque ADN extrait. Resultats Les resultats montrent que la cohorte REFGENSEP est representative de l’histoire naturelle de la maladie en comparaison avec d’autres cohortes de reference selon : — le sexe ratio, — la forme clinique, — l’âge de debut de maladie, — l’âge d’atteinte des stades EDSS 4 et 6, — la severite de la maladie evaluee par MSSS, — le genotype HLA DR2. L’effet dose de l’allele HLA DR15 dans la susceptibilite ou la severite de la sclerose en plaques est en cours d’analyse. Discussion La cohorte REFGENSEP regroupe l’ADN d’environ 850 patients et de leur apparentes. Chaque ADN est associe a des annotations cliniques et moleculaires. Elle constitue l’outil de base des etudes genetiques familiales visant a identifier des facteurs de susceptibilite ou de severite a la maladie. Elle doit etre representative de la population generale de sclerose en plaques afin qu’aucun biais ne soit introduit dans les etudes. Conclusion La caracterisation de la cohorte REFGENSEP a montre sa representativite en comparaison avec la population generale de sclerose en plaques. Cette cohorte constitue donc un outil de qualite pour les etudes genetiques.

Background Antibiotic treatment of community-acquired pneumonia (CAP) in children remains mostly empirical because clinical and paraclinical findings poorly discriminate the principal causes of CAP. Fast response to beta-lactam treatment can be considered a proxy of pneumococcal aetiology. We aimed to identify the best biological predictor of response to beta-lactam therapy in children hospitalized for CAP. Methods A retrospective, single-centre cohort study included all consecutive patients 1 month to 16 years old hospitalized in a teaching hospital in Paris, France, because of CAP empirically treated with a beta-lactam alone from 2003 to 2010. Uni- and multivariate analyses were used to study the ability of routine biological parameters available in the Emergency Department to predict a favourable response to beta-lactam (defined as apyrexia within 48 hours of treatment onset). Results Among the 125 included patients, 85% (106) showed a favourable response to beta-lactam. In multivariate logistic regression, we found procalcitonin (PCT) the only independent predictor of apyrexia (p = 0.008). The adjusted odds ratio for the decadic logarithm of PCT was 4.3 (95% CI 1.5–12.7). At ≥3 ng/mL, PCT had 55.7% sensitivity (45.7–65.3), 78.9% specificity (54.4–93.9), 93.7% positive predictive value (84.5–98.2), 24.2% negative predictive value (14.2–36.7), 2.64 positive likelihood ratio (1.09–6.42) and 0.56 negative likelihood ratio (0.41–0.77). In the 4 children with a PCT level ≥3 ng/mL and who showed no response to beta-lactam treatment, secondary pleural effusion had developed in 3, and viral co-infection was documented in 1. Conclusions PCT is the best independent biologic predictor of favourable response to beta-lactam therapy in children hospitalized for CAP. Thus, a high PCT level is highly suggestive of pneumococcal aetiology. However, a 3-ng/mL cut-off does not seem compatible with daily medical practice, and additional research is needed to further define the role of PCT in managing CAP in children.