Secondhand smoke and functional impairments in older adults

Abstract

BACKGROUND AND AIM: Secondhand smoke (SHS) is a risk factor of coronary heart disease, lung cancer, and stroke. Recent cross-sectional evidence suggests that it may also increase the risk of functional limitations, especially among older adults METHODS: We included data from 2828 community dwelling non-smoking older adults from the Seniors-Enrica-2 cohort (Madrid, Spain). Exposure to SHS was assessed by serum cotinine concentrations. At baseline (2017) and follow-up (2019), overall physical function was evaluated using the Spanish version of the physical component summary (PCS) of the 12-Item Short-Form Health questionnaire, lower-extremity performance with the Short Physical Performance Battery (SPPB), muscle weakness with a dynamometer, frailty with a Deficits Accumulation index (DAI), and disability in instrumental activities of daily living (IADL) with the Lawton-Brody questionnaire. Cross-sectional analyses were performed using linear and logistic regression models. Repeated measures models used robust standard error estimates to account for within-participant correlations induced by repeated measurements RESULTS:The median (IQR) concentrations of serum cotinine was 0.079 (0.035-0.175)ng/mL. After adjustment for potential confounders including sex, age, social class, civil status, tobacco exposure in the past, physical activity and BMI, and compared to participants with cotinine concentrations below the limit of detection (0.05ng/mL), those in the highest quartile of exposure (≥0.239ng/mL) showed baseline mean differences (95%CI) in the PCS, SPPB and muscle strength of -1.43 (-2.68,-0.18) points, -0.26 (-0.47,-0.06) points, and -1.21 (-1.92, -0.49) kilos; as well as a higher mean accumulation of deficits [2.62 (1.51,3.73)] and a higher odds of IADL limitations [1.38 (0.89, 2.14)]. In prospective analyses, the corresponding figures were -1.11 (-2.52,0.21) for PCS, -0.30 (-0.53,-0.07) for SPPB, -1.02 (-1.90,-0.13) for muscle weakness, 1.90 (0.64,3.16) for DAI and 1.15 (0.59,2.23) for IADL disability CONCLUSIONS:These findings suggest that exposure to SHS during old age may influence functional decline. If confirmed, more efforts would be needed to protect older adults from SHS KEYWORDS: Secondhand smoke, functional decline, ageing