Interaction between perceived ageism and poor sleep quality on frailty among community-dwelling older adults: a cross-sectional study

Abstract Background This study aimed to examine the associations and interaction effects of perceived ageism (PA) and poor sleep quality (SQ) on frailty among community-dwelling older adults. Methods This cross-sectional study included 4125 community-dwelling adults aged ≥ 60 from Shanghai. PA was self-reported. Participants completed the Pittsburgh Sleep Quality Index (PSQI), with a score > 5 indicating poor SQ. Frailty was assessed using a 30-item Frailty Index (FI), with participants categorized as robust (≤ 0.10), prefrail (> 0.10 and < 0.25), and frail (≥ 0.25). Both multiplicative interaction and additive interaction were evaluated. Results After adjusting for covariates, there was a significant multiplicative interaction between PA and PSQI score in relation to FI, indicating a stronger association between PSQI score and FI in participants reporting PA than those without (β = 0.489 95%CI, 0.430–0.548 vs. β = 0.276 95%CI, 0.232–0.319; P for interaction < 0.001). Furthermore, significant additive interactions between PA and poor SQ were observed for frailty (relative excess risk due to interaction RERI = 0.85 95%CI, 0.07–1.64) and prefrailty (RERI = 0.43 95%CI, 0.06–0.79) in the fully adjusted model. The attributable proportion (AP) due to interaction was 0.16 (95%CI, 0.02–0.30) for frailty and 0.15 (95%CI, 0.03–0.28) for prefrailty, indicating that approximately 16% and 15% of the associations with frailty and prefrailty were attributable to the combined effects of PA and poor SQ, respectively. Conclusion PA and poor SQ interact synergistically, accounting for a substantial proportion of the association with frailty. These findings underscore the need to target both factors in frailty management among community-dwelling older adults.