Association between home environment characteristics, indoor dust microbiota and frailty among community-dwelling older adult couples

BACKGROUND: Older adult couples exhibit prolonged indoor co-residence owing to age-related health limitations. The association between domestic environmental parameters, indoor microbiota and frailty status in older adult couples remains poorly understood. METHODS: A cross-sectional study was conducted among community-dwelling older adults to investigate associations between environmental factors, indoor microbiota and frailty status in individuals and couples. The environmental parameters encompassed architectural characteristics, indoor microclimate, air quality, lighting, noise levels and wind speed. Microbial samples underwent 16S ribosomal ribonucleic acid and internal transcribed spacer high-throughput sequencing. RESULTS: Among 141 households (226 participants), 34.8% were classified as nonfrail, 35.5% as single-frail and 29.8% as dual-frail. Multivariable analysis revealed the second quartile wet-bulb globe temperature (WBGT) demonstrated a negative association with frailty compared to the top quartile in both individual and couple analyses [adjusted odds ratio (aOR) < 1; P < .05]. Artificial illuminance in the second quartile was positively associated with couple frailty compared to the top quartile (aOR > 1; P < .05). Regarding indoor microbiota, the lowest bacterial Chao1 quartile was associated negatively with frailty, whereas the bottom fungal Chao1 quartile showed a positive association (P < .05) in both analyses. Additionally, key differentially genera, including Pseudomonas, Sanguibacter, Aerococcus, Penicillium and Lodderomyces, demonstrated positive correlations with WBGT (P < .05). CONCLUSIONS: WBGT and indoor microbiota are significantly associated with frailty status in older adult individuals and couples.