Association between household fuel use and sleep quality in the oldest-old: Evidence from a propensity-score matched case-control study in Hainan, China

Emerging evidence has documented that poor sleep quality associated with adverse effects with physical, psychological and neurological disorders, which impeded healthy aging. There is limited knowledge regarding the association of household air pollution (HAP) from solid fuel use with sleep quality, particularly among the population at advanced ages. The aim of this study is to investigate this association in oldest-old (≥80 years) populations. China Hainan Centenarian Cohort Study was conducted in the 18 cities and counties of Hainan Province from 2015 to 2017. A total of 1725 individuals aged 80 years and older were included in the study. We used the Pittsburgh sleep quality index (PSQI) to measure individuals’ sleep quality with a score of PSQI >8 indicating poor sleep quality. Solid fuel users were defined as those who primarily use coal, biomass charcoal, wood or straw for cooking in their daily life. The propensity score matching (PSM) was adopted and logistic regressions were performed based on the matched sample to estimate the association between the two factors. We adjusted for a wide range of covariates, including demographic, socioeconomic, health-related, and environmental factors. After matching, a total of 1616 participants (mean [SD] age, 94.5 [9.5] years; 72.5% women) were included in the final analysis. About 50.9% of the participants used solid fuel for cooking. The average global PSQI score was 8.26 (SD = 3.3), 49.0% of them were detected as poor sleep quality with a global PSQI score >8. We found significantly higher risk of having poor sleep quality among those who were currently solid fuel users than among clean fuel users, with an odds ratio (OR) of 1.43 (95% CI: 1.14–1.80), adjusting for a wide range of confounders. The associations were more pronounced in those who did not use any ventilation (compared to those who used either mechanical or natural cooking ventilation; 1.79 [1.30–2.47] vs. 1.27 [1.01–1.53], P for interaction = 0.016) and in those who were frequent cooking at home (compared to those who never cooked; 1.65 [1.21–2.26] vs. 1.18 [0.93–1.40], P for interaction = 0.025). Exposure to HAP from solid fuel combustion increases the risk of poor sleep quality at oldest-old ages. Our findings point to the need of reducing HAP from polluted fuel combustion and implementing cooking ventilation as a public health priority for healthy aging initiatives.