What is the impact of one's chronic illness on his or her spouse's future chronic illness: a community-based prospective cohort study

Abstract

Background: Integrating a joint approach to chronic disease management within the context of a couple has immense potential as a valuable strategy for both prevention and treatment. Although spousal concordance has been reported in specific chronic illnesses, the impact they cumulatively exert on a spouse in a longitudinal setting has not been investigated. We aimed to determine whether one's cumulative illness burden has a longitudinal impact on that of their spouse.

Methods: Data was acquired from a community-based prospective cohort that included Koreans aged 60 years and over, randomly sampled from 13 districts nationwide. Data from the baseline assessment (conducted from November 2010 to October 2012) up to the 8-year follow-up assessment was analyzed from October 2021 to November 2022. At the last assessment, partners of the index participants were invited, and we included 814 couples in the analysis after excluding 51 with incomplete variables. Chronic illness burden of the participants was measured by the Cumulative Illness Rating Scale (CIRS). Multivariable linear regression and causal mediation analysis were used to examine the longitudinal effects of index chronic illness burden at baseline and its change during follow-up on future index and spouse CIRS scores.

Results: Index participants were divided based on baseline CIRS scores (CIRS < 6 points, n = 555, mean [SD] age 66.3 [4.79] years, 43% women; CIRS ≥ 6 points, n = 259, mean [SD] age 67.7 [4.76] years, 36% women). The baseline index CIRS scores and change in index CIRS scores during follow-up were associated with the spouse CIRS scores (β = 0.154 [SE: 0.039], p < 0.001 for baseline index CIRS; β = 0.126 [SE: 0.041], p = 0.002 for change in index CIRS) at the 8-year follow-up assessment. Subgroup analysis found similar results only in the high CIRS group. The baseline index CIRS scores and change in index CIRS scores during follow-up had both direct and indirect effects on the spouse CIRS scores at the 8-year follow-up assessment.

Conclusions: The severity and course of one's chronic illnesses had a significant effect on their spouse's future chronic illness particularly when it was severe. Management strategies for chronic diseases that are centered on couples may be more effective.

Keywords: Aged; Chronic disease; Disease management; Geriatrics; Spouse.

Fig. 1

The effects of index cumulative illness burden on future spouse cumulative illness burden. Causal mediation analysis models examining the effects of index CIB (cumulative illness burden) at baseline and its change on future spouse CIB in A all subjects, B the low CIB group, and C the high CIB group. “Baseline index CIRS” refers to the CIRS scores of the index participants at the baseline visit. “Change in index CIRS” refers to the change in CIRS scores (ΔCIRS) of the index participants between the baseline visit and the 6-year follow-up visit. The spouse CIRS scores were assessed once, at the 8-year follow-up visit, and is presented as “8-year spouse CIRS.” Numbers next to arrows correspond to unstandardized regression coefficients. Black arrows indicate statistically significant effects. ACME, average causal mediation effect; ADE, average direct effect. ^†p < .01, *p < .05, **p < .01, ***p < .001