Passive smoking at home is a risk factor for community-acquired pneumonia in older adults: a population-based case–control study

OBJECTIVE To assess whether passive smoking exposure at home is a risk factor for community-acquired pneumonia (CAP) in adults. SETTING A population-based case-control study was designed in a Mediterranean area with 860 000 inhabitants >14 years of age. PARTICIPANTS 1003 participants who had never smoked were recruited. PRIMARY AND SECONDARY OUTCOME MEASURES Risk factors for CAP, including home exposure to passive smoking, were registered. All new cases of CAP in a well-defined population were consecutively recruited during a 12-month period. METHODS A population-based case-control study was designed to assess risk factors for CAP, including home exposure to passive smoking. All new cases of CAP in a well-defined population were consecutively recruited during a 12-month period. The subgroup of never smokers was selected for the present analysis. RESULTS The study sample included 471 patients with CAP and 532 controls who had never smoked. The annual incidence of CAP was estimated to be 1.14 cases×10(-3) inhabitants in passive smokers and 0.90×10(-3) in non-passive smokers (risk ratio (RR) 1.26; 95% CI 1.02 to 1.55) in the whole sample. In participants ≥65 years of age, this incidence was 2.50×10(-3) in passive smokers and 1.69×10(-3) in non-passive smokers (RR 1.48, 95% CI 1.08 to 2.03). In this last age group, the percentage of passive smokers in cases and controls was 26% and 18.1%, respectively (p=0.039), with a crude OR of 1.59 (95% CI 1.02 to 2.38) and an adjusted (by age and sex) OR of 1.56 (95% CI 1.00 to 2.45). CONCLUSIONS Passive smoking at home is a risk factor for CAP in older adults (65 years or more).