The Impact of Multimorbidity on All-Cause Mortality: A Longitudinal Study of 87,151 Thai Adults

Abstract

Objectives: To investigate associations between multimorbidity, socio-demographic and health behaviour factors, and their interactions (multimorbidity and these factors) with all-cause mortality among Thai adults. Methods: Associations between multimorbidity (coexistence of two + chronic diseases) and mortality between 2005 and 2019 were investigated among Thai Cohort Study (TCS) participants (n = 87,151). Kaplan-Meier survival curves estimated and compared survival times. Multivariate Cox proportional hazards models examined associations between risk factors, and interactions between multimorbidity, these factors, and survival. Results: 1,958 cohort members died between 2005 and 2019. The risk of death was 43% higher for multimorbid people. In multivariate Cox proportional hazard models, multimorbidity/number of chronic conditions, age, long sleep duration, smoking and drinking were all independent factors that increased mortality risk. Women, urbanizers, university education, over 20,000-baht personal monthly income and soybean products consumption lowered risk. The interactions between multimorbidity and these variables (except for female, urbanizers and soybeans intake) also had significant (p < 0.05) impact on all-cause mortality. Conclusion: The results emphasise the importance of healthy lifestyle and reduced intake of alcohol and tobacco, in reducing premature mortality, especially when suffering from multimorbidity.

Keywords: Thai Cohort Study; all-cause mortality; lifestyle behaviour; multimorbidity; socio-demographics status.

FIGURE 1

Kaplan-Meier estimated curves for cumulative survival ((A) for male and female; (B) for all participants) (Thailand, 2005 for baseline characteristics and 2019 for all-cause mortality).

FIGURE 2

Kaplan-Meier estimated curves for cumulative survival by multimorbidity ((A) for male; (B) for female; (C) for all) or number of chronic conditions ((D) for male; (E) for female; (F) for all), and gender (Thailand, 2005 for baseline characteristics and 2019 for all-cause mortality).

FIGURE 3

Kaplan-Meier estimated curves for cumulative survival by multimorbidity ((A) for ≤ 39 years old; (B) for 40-59 years old; (C) for ≥ 60 years old) or number of chronic conditions ((D) for ≤ 39 years old; (E) for 40-59 years old; (F) for ≥ 60 years old), and age (Thailand, 2005 for baseline characteristics and 2019 for all-cause mortality).