The prevalence of multimorbidity and its association with physical activity and sleep duration in middle aged and elderly adults: a longitudinal analysis from China

Table 4 Modification of the effect of sleep duration on multimorbidity by physical activity

	Good sleep [7 h–9 h]		Poor sleep [< 7 h or > 9 h]		ORs (95% CI) for poor sleep within strata of physical activity
	Number of cases/controls	OR (95% CI)	Number of cases/controls	OR (95% CI)
High physical activity	1207/1139	1	777/467	1.570 (1.364–1.807)	1.511 (1.081–2.112)
Moderate physical activity	954/ 806	1.117 (0.987–1.264)	629/ 328	1.810 (1.548–2.115)	1.832 (1.257–2.671)
Low physical activity	1636/1176	1.313 (1.176–1.466)	1063/460	2.181 (1.903–2.499)	1.552 (1.175–2.050)

Note: If moderate physical activity compared with high physical activity, measure of effect modification on additive scale: RERI (95% CI) = 0.123 (−0.264 to 0.510); If low physical activity compared with high physical activity, measure of effect modification on additive scale: RERI (95% CI) = 0.298 (−0.099 to 0.695); ORs were adjusted for age, gender, educational level, marital status, living place, household income, health insurance, Body Mass Index (BMI), smoking cigarettes, drinking alcohol and depression. OR were unadjusted for covariates. RERI relative excess risk due to interaction

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