1. This cohort study found that among 623,140 individuals participating in the Asia Cohort Consortium, being unmarried demonstrated a higher risk of all-cause and cause-specific mortality compared with being married, particularly amongst individuals younger than 65.
2. Being single was associated with higher risk of mortality among healthy participants in comparison to those with a history of cancer, cerebrovascular disease, or coronary heart disease.
Evidence Rating Level: 2 (Good)
Study Rundown: Marriage rates have decreased globally over the past few decades. In a recent meta-analysis, marital status was shown to influence mortality rates and those who were unmarried were at a higher risk of all-cause and cause-specific mortality compared to their married counterparts. Research on the association of marital status and mortality in Asian populations, however, is limited, hence this cohort study aimed to examine the association of marital status with total and cause-specific mortality in Asia. The primary exposure for this study was marital status, and the main outcomes were all-cause and cause-specific mortality. Data was pooled from a total of 623,140 participants with a mean age of 53.7 years from 16 prospective cohorts participating in the Asia Cohort Consortium. During the follow-up period of 15.5 years, 123,264 deaths were recorded, a majority due to cancer or diseases of the circulatory system. In comparison to those who were married, being unmarried was associated with an elevated total mortality (pooled hazard ratio = 1.15). This effect was particularly high in participants who were men and/or younger than 65 years. Being single was associated with a higher risk of mortality among healthy participants compared to those with a history of illness. A major strength of this study was its size, being the largest pooled analysis of Asian populations from 16 cohorts, which allowed it to provide estimates with precision. A limitation to this study due to its observational nature was the lack of data on income, which could lead to the presence of residual confounding.
Relevant Reading: Sex differences in the association between marital status and the risk of cardiovascular, cancer, and all-cause mortality: a systematic review and meta-analysis of 7,881,040 individuals
In-Depth [prospective cohort]: A total of 623,140 participants were included in this study (325,397 women [52.4%] and 296,743 mean [47.6]; mean [SD] age, 53.7 [10.2] years; the mean [SD] follow-up time was, 15.5 [6.1] years) and during this period 123,264 deaths were ascertained. Of the deaths reported, they were classified as due to: circulatory system diseases (n=37,394), coronary heart disease (n=8013), cerebrovascular disease (n=14,463), cancer (n=41,362), respiratory diseases (n=13,583), and external causes (n=7795). A two stage meta-analysis of individual participant data was performed in this study in order to estimate the pooled hazard rations (HRs) and 95% CIs. In comparison to individuals who were married, those who were unmarried had pooled HRs of 1.15 (95% CI, 1.07-1.24) for total mortality, 1.12 (95%CI, 1.03-1.22) for cerebrovascular disease mortality, 1.20 (95%CI, 1.09-1.31) for coronary heart disease mortality, 1.17 (95%CI, 1.07-1.28) for circulatory system diseases mortality, 1.06 (95%CI, 1.01-1.11) for cancer mortality, 1.14 (95%CI, 1.05-1.23) for respiratory diseases mortality, and 1.19 (95%CI, 1.05-1.34) for external causes of death. A subgroup analysis was performed to evaluate the association between marital status and mortality risk stratified by health status at baseline. Positive associations with total mortality were observed for those unmarried, including single (HR, 1.62; 95% CI, 1.41-1.86), separated (HR, 1.35; 95% CI, 1.13-1.61), divorced (HR, 1.38; 95% CI, 1.13-1.69), and widowed (HR, 1.09; 95% CI, 1.04-1.13). Among these subgroups, the risk of death was more pronounced among people younger than 65 years (HR, 1.79; 95% CI, 1.54-2.08). Lastly, being single was associated with a higher risk of mortality among healthy participants than individuals with a history of cancer, cerebrovascular disease, or coronary heart disease (P for interaction=.01).
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