Spousal Concordance in the Development of Functional Limitations Among Married Adults in China.

Importance: Functional limitation is increasingly common as people age and is often associated with negative consequences. Evidence of the dynamics of functional limitation within couples in China is still inadequate. Objectives: To examine whether functional limitation was associated within middle-aged and older couples and to explore sex differences in spousal associations. Design, Setting, and Participants: In this nationwide, population-based cohort study performed from January 1, 2011, to December 31, 2018, participants were selected using multistage probability sampling, and 5207 community-dwelling couples (10 414 individuals) 45 years or older were included in the nationally representative China Health and Retirement Longitudinal Study. Data analysis was performed from January 1 to February 28, 2021. Exposures: The exposure variable was the presence of functional limitation in spouses. Functional limitation was measured by the activities of daily living (ADLs) and instrumental activities‎ of daily ‎living (IADLs) scales and was defined as having difficulty in independently performing at least 1 ADL or IADL item. Main Outcomes and Measures: The main outcome was functional limitation in index participants. Multivariable logistic regression with generalized estimating equations was used to estimate the reciprocal association of functional limitation within couples over time. Results: A total of 5207 married, different-sex couples (mean [SD] age, 59.1 [8.8] years for husbands and 57.0 [8.2] years for wives) were included in the study. For husbands, the number (percentage) of participants classified with baseline functional limitation was 1140 (21.9%), the number (percentage) with ADL limitation was 684 (13.1%), and the number (percentage) with IADL limitation was 834 (16.0%). For wives, the number (percentage) of participants classified with baseline functional limitation was 1502 (28.8%), the number (percentage) with ADL limitation was 887 (17.0%), and the number (percentage) with IADL limitation was 1183 (22.7%). Longitudinal results demonstrated an association in spouses developing functional limitation (adjusted odds ratio [OR], 2.55; 95% CI, 2.41-2.69; P < .001), ADL limitation (adjusted OR, 2.26; 95% CI, 2.11-2.41; P < .001), and IADL limitation (adjusted OR, 2.58; 95% CI, 2.43-2.73; P < .001). Subgroup analyses by sex revealed similar patterns of spousal health concordance in terms of all studied outcomes, indicating no sex specificity. Conclusions and Relevance: This population-based cohort study suggests that among Chinese middle-aged and older couples there is significant concordance in the development of functional limitation. This study of spousal functional ability from a dyadic perspective may help in the understanding of health risks within a wider familial context and offers novel insights for prioritizing policy focus from individual centered to couple based.