Relationship of peak expiratory flow rate with mortality and ischaemic heart disease in elderly Australians

OBJECTIVE: To evaluate the relationships of mortality and ischaemic heart disease (IHD) with peak expiratory flow rate (PEF) in the elderly. DESIGN: Prospective study with median follow-up of 83 months. SETTING: Dubbo, a New South Wales country town (population, 30500). SUBJECTS: Non-institutionalised residents born before 1930 (i.e., aged 60 years and over at study entry). Participation rate was 73% (1235 men and 1570 women). MAIN OUTCOME MEASURES: Baseline demographic, psychosocial and standard cardiovascular risk factors, including PEF; all-causes mortality, IHD mortality and IHD events (hospitalisations with any manifestation of IHD) by tertile of PEF. RESULTS: More subjects with PEF in the lowest tertile (I) had a past history of respiratory disease, were current cigarette smokers and were taking antihypertensive drugs. During follow-up, 321 men (26%) and 252 women (16%) died. All-causes mortality was three (men) to four (women) times higher for those in PEF tertile I than for those in tertile III. IHD mortality and IHD events showed similar trends. In a proportional hazards model adjusted for age, height, smoking status and other risk factors or confounders, the hazard ratios (95% confidence interval) for men in PEF tertile I versus tertile III were: all-causes mortality, 1.62 (1.14-2.30); IHD mortality, 1.75 (0.96-3.20); and IHD events, 1.12 (0.82-1.53). For women, respective hazard ratios were 1.92 (1.23-3.00), 2.58 (1.24-5.39), and 1.16 (0.83-1.63). CONCLUSIONS: We confirm an independent, inverse relationship between PEF and all-causes and IHD mortality. The data suggest a potential benefit for coronary risk factor management in subjects with existing airways disease and further support the case for antismoking programs.