Effects of bidi smoking on all-cause mortality and cardiorespiratory outcomes in men from south Asia: an observational community-based substudy of the Prospective Urban Rural Epidemiology Study (PURE)

Background: Bidis are minimally regulated, inexpensive, hand-rolled tobacco products smoked in south Asia. We examined the effects of bidi smoking on baseline respiratory impairment, and prospectively collected data for all-cause mortality and cardiorespiratory events in men from this region. Methods: This substudy of the international, community-based Prospective Urban Rural Epidemiology (PURE) study was done in seven centres in India, Pakistan, and Bangladesh. Men aged 35–70 years completed spirometry testing and standardised questionnaires at baseline and were followed up yearly. We used multilevel regression to compare cross-sectional baseline cardiorespiratory symptoms, spirometry measurements, and follow-up events (all-cause mortality, cardiovascular events, respiratory events) adjusted for socioeconomic status and baseline risk factors between non-smokers, light smokers of bidis or cigarettes (≤10 pack-years), heavy smokers of cigarettes only (>10 pack-years), and heavy smokers of bidis (>10 pack-years). Findings: 14 919 men from 158 communities were included in this substudy (8438 non-smokers, 3321 light smokers, 959 heavy cigarette smokers, and 2201 heavy bidi smokers). Mean duration of follow-up was 5·6 years (range 1–13). The adjusted prevalence of self-reported chronic wheeze, cough or sputum, dyspnoea, and chest pain at baseline increased across the categories of non-smokers, light smokers, heavy cigarette smokers, and heavy bidi smokers (p<0·0001 for association). Adjusted cross-sectional age-related changes in forced expiratory volume in 1 s (FEV1) and FEV1/forced vital capacity (FVC) ratio were larger for heavy bidi smokers than for the other smoking categories. Hazard ratios (relative to non-smokers) showed increasing hazards for all-cause mortality (light smokers 1·28 [95% CI 1·02–1·62], heavy cigarette smokers 1·59 [1·13–2·24], heavy bidi smokers 1·56 [1·22–1·98]), cardiovascular events (1·45 [1·13–1·84], 1·47 [1·05–2·06], 1·55 [1·17–2·06], respectively) and respiratory events (1·30 [0·91–1·85], 1·21 [0·70–2·07], 1·73 [1·23–2·45], respectively) across the smoking categories. Interpretation: Bidi smoking is associated with severe baseline respiratory impairment, all-cause mortality, and cardiorespiratory outcomes. Stricter controls and regulation of bidis are needed to reduce the tobacco-related disease burden in south Asia. Funding: Population Health Research Institute, Canadian Institutes of Health Research, and Heart and Stroke Foundation of Ontario

Mortality and cardiovascular and respiratory morbidity in individuals with impaired FEV1 (PURE): an international, community-based cohort study

Summary: Background: The associations between the extent of forced expiratory volume in 1 s (FEV1) impairment and mortality, incident cardiovascular disease, and respiratory hospitalisations are unclear, and how these associations might vary across populations is unknown. Methods: In this international, community-based cohort study, we prospectively enrolled adults aged 35–70 years who had no intention of moving residences for 4 years from rural and urban communities across 17 countries. A portable spirometer was used to assess FEV1. FEV1 values were standardised within countries for height, age, and sex, and expressed as a percentage of the country-specific predicted FEV1 value (FEV1%). FEV1% was categorised as no impairment (FEV1% ≥0 SD from country-specific mean), mild impairment (FEV1% <0 SD to −1 SD), moderate impairment (FEV1% <–1 SD to −2 SDs), and severe impairment (FEV1% <–2 SDs [ie, clinically abnormal range]). Follow-up was done every 3 years to collect information on mortality, cardiovascular disease outcomes (including myocardial infarction, stroke, sudden death, or congestive heart failure), and respiratory hospitalisations (from chronic obstructive pulmonary disease, asthma, pneumonia, tuberculosis, or other pulmonary conditions). Fully adjusted hazard ratios (HRs) were calculated by multilevel Cox regression. Findings: Among 126 359 adults with acceptable spirometry data available, during a median 7·8 years (IQR 5·6–9·5) of follow-up, 5488 (4·3%) deaths, 5734 (4·5%) cardiovascular disease events, and 1948 (1·5%) respiratory hospitalisation events occurred. Relative to the no impairment group, mild to severe FEV1% impairments were associated with graded increases in mortality (HR 1·27 [95% CI 1·18–1·36] for mild, 1·74 [1·60–1·90] for moderate, and 2·54 [2·26–2·86] for severe impairment), cardiovascular disease (1·18 [1·10–1·26], 1·39 [1·28–1·51], 2·02 [1·75–2·32]), and respiratory hospitalisation (1·39 [1·24–1·56], 2·02 [1·75–2·32], 2·97 [2·45–3·60]), and this pattern persisted in subgroup analyses considering country income level and various baseline risk factors. Population-attributable risk for mortality (adjusted for age, sex, and country income) from mildly to moderately reduced FEV1% (24·7% [22·2–27·2]) was larger than that from severely reduced FEV1% (3·7% [2·1–5·2]) and from tobacco use (19·7% [17·2–22·3]), previous cardiovascular disease (5·5% [4·5–6·5]), and hypertension (17·1% [14·6–19·6]). Population-attributable risk for cardiovascular disease from mildly to moderately reduced FEV1 was 17·3% (14·8–19·7), second only to the contribution of hypertension (30·1% [27·6–32·5]). Interpretation: FEV1 is an independent and generalisable predictor of mortality, cardiovascular disease, and respiratory hospitalisation, even across the clinically normal range (mild to moderate impairment). Funding: Population Health Research Institute, the Canadian Institutes of Health Research, Heart and Stroke Foundation of Ontario, Ontario Ministry of Health and Long-Term Care, AstraZeneca, Sanofi-Aventis, Boehringer Ingelheim, Servier, and GlaxoSmithKline, Novartis, and King Pharma. Additional funders are listed in the appendix