Secondhand tobacco smoke and functional impairments in older adults living in the community

Abstract

Background/aim: there has been no comprehensive examination of the potential association of SHS with broad functional limitation assessment in older adults, where functional limitations are burdensome and challenging. Methods: we examined 2258 community-dwelling non-smoking older adults from the Seniors-Enrica-2-cohort. At baseline (2017) and follow-up (2019) grip strength was measured with a Jamar dynamometer, lower-extremity performance with the Short Physical Performance Battery (SPPB), overall physical function using the physical component summary (PCS) of the Spanish version of the SF-12, frailty with a Deficits Accumulation Index (DAI), and mobility limitations with the Rosow-Breslau scale. Baseline exposure to SHS was assessed by serum cotinine, and past exposure was self-reported. Cross-sectional analyses were performed using linear and logistic regression models, whereas functional performance changes were examined using repeated measures models with robust SE estimates. Results: overall, the median (IQR) serum cotinine concentration was 0.079 (0.035-0.175) ng/ml, with 20 participants presenting concentrations ≥3 ng/ml. Compared to the unexposed, fully-adjusted models showed that the highest exposure group (≥0.239 ng/ml) presented lower grip strength (mean difference: -1.05 kg; 95% CI = -1.80, -0.31) and higher DAI scores (1.52; 95% CI = 0.38, 2.66) at baseline. Similarly, in models of self-reported past exposure, never-smokers who had lived with ≥2 smokers or been exposed to higher SHS cumulative doses showed lower baseline SPPB values, higher DAI scores, and higher prevalence of mobility limitations. In prospective analyses, those in the highest quartile of baseline cotinine presented harmful SPPB [-0.24 (-0.46, -0.02)] and DAI [1.28 (0.00, 2.55)] changes, and higher risk of mobility limitations [hazard ratio: 1.64; 95% CI = 1.01, 2.68] than the unexposed. Conclusions: SHS exposure over the life-course and during old age may accelerate functional decline. Implications: this manuscript provides a comprehensive examination of the relationship between secondhand smoke exposure and a broad range of functional limitations in older adults. Results show that: (i) non-smokers who had been exposed to higher cumulative doses of SHS in adulthood show worse physical function than non-exposed. (ii) Exposure to SHS during old age, as measured with cotinine concentrations, is associated with accelerated short-term functional declines. (iii) The effects of SHS are stronger among older adults with chronic morbidities. (iv) Results suggest that more efforts are needed to protect older adults from passive smoking, especially to those with chronic conditions because of their potential greater vulnerability to the effects of SHS.