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ObjectivesIn Barbados, high case fatality rates have been reported after myocardial infarction (MI) with higher rates in women than men. To explore this inequality, we examined documented pharmacological interventions for ST-segment elevated myocardial infarction (STEMI), non-STEMI (NSTEMI) and unstable and chronic angina in women and men.DesignProspective cohort registry data for STEMI and NSTEMI and retrospective chart review for unstable and chronic angina.SettingTertiary care (acute coronary syndromes) and primary care (chronic angina) centres in Barbados.ParticipantsFor the years 2009–2016, a total of 1018 patients with STEMI or NSTEMI were identified via the prospective study. For unstable and chronic angina, 136 and 272 notes were reviewed respectively for the years 2010–2014.Outcome measuresThe proportions of patients prescribed recommended medication during the first 24 hours after an acute event, at discharge and for chronic care were calculated. Prescribed proportions were analysed by gender after adjustment for age.ResultsBetween 2009 and 2016, for the acute management of patients with NSTEMI and STEMI, only two (aspirin and clopidogrel) of six drugs had documented prescription rates of 80% or more. Patients with STEMI (n=552) had higher prescription rates than NSTEMI (n=466), with gender differences being more pronounced in the former. Among patients with STEMI, after adjustment for age, diabetes, hypertension and smoking, men were more likely to receive fibrinolytics acutely, OR 2.28 (95% CI 1.24 to 4.21). Compared with men, a higher proportion of women were discharged on all recommended treatments; this was only statistically significant for beta-blockers: age-adjusted OR 1.87 (95% CI 1.16 to 3.00). There were no statistically significant differences in documented prescription of drugs for chronic angina.ConclusionFollowing acute MI in Barbados, the proportion of patients with documented recommended treatment is relatively low. Although women were less likely to receive appropriate acute care than men, by discharge gender differences were reversed.

Background: Smoking remains very common in Chinese men, and the economic burden caused by cigarette consumption on smokers and their families may be substantial. Using a large nationally representative household survey, the third National Health Services Survey (NHSS, 2003), we estimated the economic impact of smoking on households.\ud Methods: Smoking status of all household members (over 15 years) was collected by interview for the NHSS, and households classified into one of seven categories based on their smoking status. Information on household income and expenditure, and use of health services was also obtained. We assessed both the "direct'' costs (reducing funds available for spending on other commodities such as food, education, medical care, etc, using a fractional logit model), and "indirect costs'' (increasing medical expenditures, using a log-linear model).\ud Results: Every five packets of cigarettes consumed per capita per month reduces household spending on other commodities, most notably on education (by about 17 yuan per capita per annum) and medical care (11 yuan). The effects are greatest among low-income rural households. Households with quitters spend substantially more on medical care than never-smoking households (64 yuan for households with two or more quitters).\ud Conclusions: If a household member smokes, there is less money available for commodities such as education and medical care. Medical care expenditure is substantially higher among households with quitters, as ill-health is the main reason for quitting smoking in China. Smoking impoverishes a substantial number of poorer rural households.

Study objectives: To examine the proportion of the recent decline in coronary heart disease (CHD) deaths in Ireland attributable to ( a) "evidence based'' medical and surgical treatments, and (b) changes in major cardiovascular risk factors.\ud Design setting: IMPACT, a previously validated model, was used to combine and analyse data on the use and effectiveness of specific cardiology treatments and risk factor trends, stratified by age and sex. The main data sources were published trials and meta-analyses, official statistics, clinical audits, and observational studies.\ud Results: Between 1985 and 2000, CHD mortality rates in Ireland fell by 47% in those aged 25 - 84. Some 43.6% of the observed decrease in mortality was attributed to treatment effects and 48.1% to favourable population risk factor trends; specifically declining smoking prevalence (25.6%), mean cholesterol concentrations (30.2%), and blood pressure levels (6.0%), but offset by increases in adverse population trends related to obesity, diabetes, and inactivity (-13.8%).\ud Conclusions: The results emphasise the importance of a comprehensive strategy that maximises population coverage of effective treatments, and that actively promotes primary prevention, particularly tobacco control and a cardioprotective diet.

Background Many studies have found an increased risk of pulmonary tuberculosis (PTB) amongst those with Diabetes Mellitus (DM), however, evidence on whether the association is specific to disease sub-types or is bi-directional remains sparse. This study assesses rates of TB, PTB and EPTB amongst those with DM, Type 1 DM (T1DM) and Type 2 DM (T2DM) comparative to those without. It also assesses the converse to investigate association bi-directionality. Methods Retrospective cohort analyses were completed using primary care data from The Health Improvement Network database (2003–2009). Individuals were classified as either exposed to or unexposed to TB, PTB, EPTB, DM, T1DM or T2DM. The incidence rate ratios (IRR) were calculated amongst each exposure group for outcomes of interest (TB, PTB, EPTB or DM, T1DM, T2DM) using negative binomial regression. Results TB risk was increased amongst individuals with any DM type (IRR 1.50 (95% CI 1.27–1.76) p Discussion Within a UK setting, TB risk was increased in those with DM as is DM risk amongst those who have had TB. We are not aware of other studies with sufficient power to assess the risk of DM among those with prior TB. Consideration of the specificity and directionality of these associations will be important in improving TB control and treatment as DM prevalence rises globally. Given the associations identified, it is likely the numbers of individuals suffering from co-morbid disease will burgeon with a need for heightened clinical attention to improve both diabetes control and TB outcomes.

Background Since mid-1980s, coronary heart disease (CHD) mortality rates in Sweden have more than halved, largely reflecting improvements in cardiovascular risk factors, mainly improvements in total cholesterol. However, this favourable trend in total cholesterol has recently levelled off or even increased in some ages, associated to changes in diet that is richer in saturated fats (SFs) and low in carbohydrates. The purpose of the present study was to project future CHD mortality in Sweden taking into account future trends in dietary SFs intake. Methods The previously validated IMPACT model was used to predict changes in CHD mortality between 2010 and 2025 in the Swedish population aged 25–84. Calculations were based on a) Population numbers and projections (the Swedish National Board of Health and Welfare) b) Population risk factors levels and projections c) effects of risk factor reductions (published meta-analyses and case-control studies). We assumed that the observed historical trend in CHD mortality were to continue and compared three different scenarios for future SFs intake, with and without favourable changes in other major risk factors: - S1: Reduction in daily intake of SFs in Sweden to 10% total energy (E) assuming substitution with unsaturated fats; - S2: Continuing current trends in SFs intake; - S3: Increasing intake of SF (20% E, consistent with fat-rich, low carb diet) 95% CI were obtained using a probabilistic sensitivity analysis Results If current CHD mortality trend would continue, 5,975 deaths would be observed in 2025. For S1 scenario 810 (664–955) fewer deaths would occur, resulting in 13.6% (11.9–15.0) mortality reduction. According to S2 scenario, no change in CHD mortality is expected. However if we assume no concurrent favourable changes in other risk factors, expected number of CHD deaths for S2 would be 382 (293–485), about 6.4% (5.1–7.8) increase. For S3 number expected increase in deaths would be 21 (–59–115), but if other risk factors would remain constant this number rises to 401 (334–475), which is equivalent to 6.7% (95% CI: 6.0–7.5) CHD mortality increase. Conclusion CHD mortality can increase as a result of unfavourable trends in diets rich in SFs resulting in cholesterol increases. While favourable trends in other risk factors might reduce its impact, substituting “bad” SFS (from dairy products and meat), with “good” mono-unsaturated (such as olive oil) and poly-unsaturated fats (such as sunflower and canola) is eminently feasible. These small and achievable beneficial dietary changes would have a large effect on CHD mortality.

Background Coronary heart disease (CHD) remains a leading cause of UK mortality, generating a large and unequal burden of disease. CHD costs the UK in excess of £6 billion annually, with estimated statins costs exceeding £840 million. Dietary trans fats represent a powerful CHD risk factor. However, UK efforts to reduce intake (currently approximately 1% of daily energy) have been less successful than some other nations, such as Denmark and the USA. Furthermore, the potential heath and economic outcomes of a legislative ban, and the effects upon health inequalities, have not been well quantified. We therefore aimed to model the potential health and economic effects of a UK legislative ban on industrial trans fats up to 2030. Methods We extended the previously validated IMPACTsec model, to estimate the potential effects of a ban on dietary industrial trans fats upon the England and Wales population aged over 25 years. We stratified these estimates by age, sex and socio-economic circumstances. Data sources included Hospital Episode Statistics, General Practice Registry Database, and Office of National Statistics. Cost data was sourced from Department of Health, NICE and British Retail Consortium. We estimated the subsequent economic effects of a legislative ban upon healthcare, informal care, productivity, and industry and the disease burden (expected CHD deaths, life years gained (LYGs), Quality adjusted life years (QALYs) and hospital admissions) over a 15 year horizon to 2030. The baseline results were tested in a probabilistic sensitivity analysis. Results A legislative ban on industrial trans fats across the England and Wales population, reducing intake to 0.5% of daily energy intake would result in approximately 5468 fewer deaths per year, (95% confidence intervals (CI) 5459–5477), with some 6000 fewer hospital admissions (95% CI 5300–6700); and gaining approximately 43,400 additional life years (95% CI 43,200–43,700). This would also reduce health inequalities, having a substantially larger beneficial effect upon mortality and LYGs in the most deprived, than the most affluent. A legislative ban could result in savings in excess of approximately £2 billion and generate gains of over 400,000 QALYs over a 15 year period. This would include annual savings of approximately £16 million in direct healthcare costs, some £50 million productivity gains and approximately £70 million savings in informal care costs. Industry reformulation costs would be relatively small. Conclusion Eliminating the UK dietary intake of industrial trans fats could substantially decrease CHD mortality, whilst also resulting in substantial savings annually. Urgent fiscal or legislative action is warranted.

Background Between 2000 and 2010, coronary heart disease (CHD) mortality rates in Scotland fell by over one third. Important contributions came from reductions in blood pressure and serum cholesterol (primary prevention). However, the relative contributions from preventive medications (anti-hypertensives and statins) in individuals and from population-wide dietary changes remain unclear. We therefore examined the impact of differential effects on health inequalities. Methods We used the previously validated IMPACTsec model to estimate the contributions of population-level risk factor changes and treatment changes to the CHD mortality decline in Scotland between 2000 and 2010 for adults aged over 25. Data were stratified using the Scottish Index of Multiple Deprivation (SIMD), a small area measure of deprivation. Model outputs were quantified as deaths prevented or postponed (DPPs) by each intervention. Sensitivity analyses were conducted using Ersatz-based Monte Carlo simulations. Results Between 2000 and 2010, 5770 fewer CHD deaths than expected occurred in Scotland; an estimated 3570 (62%) were attributable to reductions in blood pressure and serum cholesterol. Declines in blood pressure were responsible for approximately 2285 DPPs (minimum estimate 1630, maximum estimate 2915). The vast majority (2130 DPPs) came from population-wide blood pressure falls, with bigger absolute mortality decreases in the most deprived quintile compared with the least deprived (460 vs. 340 DPPs respectively); relative contributions were similar (37.2% and 37.5%). Anti-hypertension medications resulted in only 155 fewer deaths, with similar DPPs in the most (35) and least (30) deprived quintiles. Reductions in serum cholesterol resulted in 1280 fewer deaths; approximately 515 of these were attributable to population-wide changes in diet with more deaths prevented in the most deprived quintile compared with the least deprived (170 vs. 45 DPPs; relative contribution 13.8% and 4.7%). Conversely, approximately 770 fewer deaths were attributable to statin use, with very similar absolute numbers of deaths prevented in most (140) and least (140) deprived quintiles, but relatively greater contributions in the least deprived (15.4% vs 11.2%). Statin uptake was higher in the most deprived areas (17% vs 13.2%). Conclusion Population-wide falls in blood pressure helped to reduce CHD mortality; however the benefit from hypertension treatment was small. Improved diet and statins for high-risk individuals both made important contributions to the fall in population cholesterol. Population-wide falls in blood pressure and reductions due to medical treatments for hypertension were equitable between socio-economic groups. Higher socio-economic groups appeared to benefit more from statins, probably due to better compliance; this may perpetuate inequalities.

Background Coronary Heart Disease (CHD) disease remains a leading cause of UK mortality, generating a large and unequal burden of disease. Dietary trans fats represent a powerful CHD risk factor. However, UK efforts to reduce the dietary intake of industrial trans fats (currently approximately 1% of daily energy) have been less successful than some other nations, such as Denmark, Iceland, Austria, Switzerland and the USA. Furthermore, the potential outcomes of such measures, and the effects upon health inequalities, have not been well quantified. We therefore aimed to model the potential effects of specific reductions in trans fats intake on CHD mortality, CHD related admissions, and further examined the potential distribution of these effects by socio-economic position up to 2030. Methods We extended the previously validated IMPACTsec model, to estimate the potential effects of reductions in trans fats intake upon the England and Wales population aged 25 years and above. We stratified these estimates by age, sex and socio-economic circumstances (SEC). We estimated a reduction in expected CHD deaths in 2030 attributable to a modest reduction in industrial trans fats intake (-0.5% energy) and a complete ban (-1% energy). Main output measures were deaths prevented or postponed, life years gained and hospital admissions. Results were tested in a probabilistic sensitivity analysis. Results Reducing trans fats consumption in the England and Wales population by 0.5% of daily energy intake would result in approximately 1900 fewer deaths per year (minimum estimate 1700, maximum estimate 2200), some 5000 fewer hospital admissions (min 4300, max 5700), and approximately 18,000 additional life years (min 15,000, max 22,000). This would also reduce health inequalities, preventing about six times as many deaths and gaining six times as many life years in the most deprived quintile compared with the most affluent. Complete elimination of industrial trans fats (a 1% reduction in energy) would generate approximately 3900 (min 3300, max 4400) fewer deaths, 10,000 (min 8800, max 10,300) fewer hospital admissions, and approximately 37,000 (min 30,000, max 45,000) life years gained. Reductions in inequalities would be correspondingly large. Discussion Reducing dietary intake of industrial trans fats could substantially decrease CHD mortality and hospital admissions, and gain tens of thousands of life years. Crucially, this policy could also reduce health inequalities. UK strategies should therefore aim to minimise industrial trans fats intakes, as successfully achieved in many other European countries.

Background Middle income countries are facing an epidemic of non-communicable diseases, especially coronary heart disease (CHD). We used a previously validated CHD mortality model (IMPACT) to examine recent trends in CHD mortality in Tunisia, Syria, the occupied Palestinian territory (oPt – West Bank) and Turkey. Methods Data on populations, mortality, patient groups and numbers, treatments and risk factor trends from national and local surveys in each country were collated over two time points. Populations of studied countries and timeframes for this analysis were: Tunisia (10 million, 1997–2009), Syria (19 million, 1996–2006), OPt (2.5 million, 1998–2009) and Turkey (73 million, 1995–2008). We integrated and analysed data using the IMPACT model, with uncertainty explored using probabilistic sensitivity analyses. We reported the percentage of the observed change in CHD deaths explained by changes in uptake of medical and surgical treatments and major CHD risk factors for each country. Results Risk factor trends: Regional smoking prevalences were high in men, persisting in Syria but decreasing in Tunisia (-11%), oPt (-25%) and Turkey (-45%). Obesity (body mass index) rose by 1–2kg/m 2 and diabetes prevalence increased by 40%–50% in all four countries. Mean systolic blood pressure and cholesterol levels increased in Tunisia and Syria but decreased in oPt and stayed constant in Turkey. Mortality trends: Age adjusted CHD mortality rates rose by 30% in Tunisia (49/10 5 to 64/10 5 ) and by 56% in Syria (108/10 5 to 169/10 5 ). Much of this increase (98% in Tunisia, and 80% in Syria) was attributable to adverse trends in major risk factors, and occurred despite some improvements in treatment uptake. CHD mortality rates fell by 25% in oPt (85/10 5 to 64/10 5 ) and by 17% in Turkey (418/10 5 to 345/10 5 ), with risk factor changes accounting for around 65% and 60% of this reduction respectively. Increased uptake of community treatments accounted for the remainder. The IMPACT model explained approximately 77% of the observed mortality trends in Turkey and oPt, but less in Syria and Tunisia. Results remained fairly consistent following sensitivity analyses. Conclusion Eastern Mediterranean countries have shown highly heterogeneous trends in blood pressure, blood cholesterol and CHD mortality. Death rates are rising in Tunisia and Syria, whilst Turkey and occupied Palestinian territories demonstrate clear mortality falls, reflecting improvements in major cardiovascular risk factors, plus contributions from community-based medical treatments. However, across the region, smoking prevalence remains very high in men, and obesity and diabetes levels are rising dramatically. Powerful prevention policies exist and should now be implemented.

Background Poland has experienced one of the most dramatic declines in coronary heart disease (CHD) mortality rates in recent decades. This decline reflects the use of evidence based treatments and, crucially, population wide changes in diet. Our aim is to explore the potential for further gains in Poland by achieving population wide reductions in smoking, dietary salt and saturated fat intake and physical inactivity levels. Methods A validated and updated policy model was used to forecast potential decreases in CHD deaths by 2020 as consequence of lifestyle and dietary changes in the population. Data from the most recent Polish risk factor survey was used for the baseline estimates (2011). We modelled two different policy scenarios regarding possible future changes in risk factors: A) conservative scenario: reduction of smoking prevalence and physically inactivity rates by 5% between 2011 and 2020, and reduction of dietary consumption of energy from saturated fats by 1% and of salt by 10%. B) ideal scenario: reduction of smoking and physically inactivity prevalence by 15%, and dietary reduction of energy from saturated fats by 3% and of salt by 30%. We also conducted extensive sensitivity analysis using different counterfactual scenarios of future mortality trends. Results Baseline scenarios: by assuming continuing declines in mortality and no future improvements in risk factors the predicted number of CHD deaths in 2020 would be approximately 13,600 (95% CI 9838, 18184) while if mortality rates remain stable, the predicted number of deaths would approximate 22,200 (7792, 26688). Conservative scenario. Assuming continuing declines in mortality, small changes in risk factors could result in approximately 1500 (688, 2490) fewer deaths. This corresponds to an 11% mortality reduction. Under the ideal scenario, our model predicted some 4,600 (2048, 8701) fewer deaths (a 34% mortality reduction). Reduction in smoking prevalence by 5% (conservative scenario) or 15% (ideal scenario) could result in mortality reductions of 4.5% and 13.8% respectively. Decreases in salt intake by 10% or 30% might reduce CHD deaths by 3.0% and 8.6% respectively. Replacing 1% or 3% of dietary saturated fats by poly-unsaturates could reduce CHD deaths by 2.6% or 7.7%. Lowering the prevalence of physically inactive people by 5-15% could decrease CHD deaths by 1.2-3.7%. Conclusion Small and eminently feasible population reductions in lifestyle related risk factors could substantially decrease future number of CHD deaths in Poland, thus consolidating the earlier gains.

Background Despite rapidly declining coronary heart disease (CHD) mortality rates over the last two decades, CHD mortality rates in the British Isles are still amongst the highest in Europe. Greater risk factor reductions have been achieved in many other countries in Europe and beyond. This study aimed to use a modelling approach to assess the potential impact of alternative future risk factor scenarios relating to smoking and physical activity levels, dietary salt and saturated fat intakes on future CHD mortality in three countries: Northern Ireland (NI), Republic of Ireland (RoI) and Scotland. Methods CHD mortality models previously developed and validated in each country were extended to predict potential reductions in CHD mortality from 2010 (baseline year) to 2030. For each country, using risk factor data from recent surveys as a baseline, we modelled alternative future risk factor scenarios: Absolute decreases in (i) smoking prevalence and (ii) physical inactivity rates of up to 15% by 2030; (iii) relative decreases in dietary salt intake of up to 30% by 2030 & (iv) relative decreases in% energy from dietary saturated fat of up to 6% by 2030 (replacing by polyunsaturated fats). Sensitivity analyses were then conducted. Results Projected populations by 2030 (adults aged 25-84) were 1.3, 3.9 and 3.9 million in NI, RoI and Scotland respectively. By 2030: assuming continuing declines in mortality: 15% absolute reductions in smoking could decrease CHD deaths by 6–8% (approximately 40, 130 and 210 fewer deaths In NI, RoI and Scotland respectively). 15% absolute declines in physical inactivity levels might decrease CHD deaths by 4% (approximately 30, 90 and 90 fewer deaths respectively). Relative reductions in salt intake of 30% could decrease CHD deaths by 3–4% (approximately 25, 75 and 110 fewer deaths respectively) and 6% in saturated fat intake might decrease CHD deaths by some 9–10% (approximately 65, 170 and 265 fewer deaths In NI, RoI and Scotland respectively). These projections remained stable under a wide range of sensitivity analyses. Conclusion Modest and feasible reductions in four CHD risk factors (which have already been achieved elsewhere) could translate into substantial reductions in future CHD deaths. More aggressive polices are therefore needed in the British Isles to control tobacco, promote healthy food and increase physical activity.

Introduction Current projections of diabetes prevalence are mostly based on demographic change. Explicitly including trends in obesity and other risk factors could improve the accuracy of the projections and assist in evaluating policy options for prevention. Methods The model integrates population, obesity and smoking trends to estimate future diabetes prevalence using a Markov approach. Model parameters were derived from the literature, except for diabetes incidence which was estimated using DISMOD from the baseline estimation of diabetes prevalence. We developed a model for the US population (2000–2006), and validated the model outputs (NHANES prevalence and projections using a different model). Results US Diabetes mellitus prevalence estimated by the model (aged 25+) was 9.7% in 2000–2002 (7.8%–11.6%), increasing to 10.7% (8.6.3%–12.7%) by 2003–2006. Comparisons of the model results with the observed prevalence in the NHANES survey showed a close fit to the observed estimates (NHANES prevance 2003–2006 10.3%, 9.3%–11.3). The forecasts for 2030 was 19 19.3% (15.3%–23.0%). A different model (Narayan et al ) for the same period and age group were 20.2%, 18.8%–21.6%. We tested the model for the England and Wales population obtaining a similar performance. Conclusions This model provides a reasonably close estimate of diabetes prevalence for the USA over the 2000–2006 period, compared with contemporary independent prevalence surveys in the same population and with a different model. Because of its few data requirements, the approach is now being tested in different middle income countries as a potential global diabetes prevalence forecast tool.

Background Current projections of diabetes prevalence are mostly based on demographic change. Explicitly including trends in obesity and other risk factors could improve the accuracy of the projections and assist in evaluating policy options for prevention. Methods The model integrates population, obesity and smoking trends to estimate future diabetes prevalence. From three starting states (healthy, obese and smokers) the number of people with diabetes and deaths by diabetes status are estimated using a Markov approach. The transition probabilities and RR associated with risk factors were obtained from the literature, except for diabetes incidence that was estimated using DISMOD. For validation purposes, we developed a model for the England and Wales population (1993–2006), and compared model outputs with diabetes prevalence reported by the Health Survey for England (HSE) and the English Longitudinal Study of Ageing (ELSA). Results The prevalence of diabetes mellitus in England and Wales in 1993 was 3% in men and 2% in women (HSE; adjusted for self reporting, 3.9% and 2.6% respectively) and increased to 6% and 4% (7.3% and 5.5%, adjusted) by 2006. Obesity prevalence almost doubled and smoking trends showed a more complex pattern. Comparisons with the HSE showed almost parallel trends, over a period of 13 years. Prevalence as estimated from the model was 7.3% for men and 5.7% for women for 2006 and 8.9% and 7.2% for 2012. The model tends to slightly overestimate prevalence but accuracy improved in later years. The estimated prevalence compared well with that reported in ELSA (Men: model: 9.9%, ELSA: 11.6%; women: 8.3% and 6.8%). Conclusions The model provide a reasonably close estimate of diabetes prevalence for England over the 1993–2006 period, compared with contemporary independent prevalence surveys in the same population. Although the model seems to slightly overestimate prevalence, the observed and modelled trends are almost parallel. Further testing and validation in a range of populations would be desirable but the model appears to provide reasonably accurate estimates of diabetes prevalence that could be used by policymakers.

Most explanations of falls in coronary heart disease (CHD) mortality limit themselves to event based metrics (such as fewer deaths). However, time based metrics (such as life-years gained (LYG)) promise to capture more of the social value attached to the deaths averted. We have assessed the sensitivity of conclusions about the relative contributions of treatments and risk factor changes to the choice of metric. Using a validated CHD mortality model (IMPACT), we integrated data on the number …

Tuberculosis (TB) remains a major global health problem. A possible risk factor for TB is diabetes (DM), which is predicted to increase dramatically over the next two decades, particularly in low- and middle-income countries, where TB is widespread. This convergence of two epidemics has highlighted the need for a better understanding of the possible association between the two diseases, and its potential significance for public health. This study aimed to assess the strength of the association between TB and …

Editor–Enstrom and Kabat's analysis has several omissions.1 First they accept that most epidemiological studies have found positive but not statistically significant relationships between environmental tobacco smoke, coronary heart disease, and lung cancer, but then argue against meta-analysis to establish a causal relation. This is precisely where systematic reviews, and sometimes meta-analysis, show …