Accounting for health benefits while adjusting for observational data

8. Accounting for health benefits while adjusting for observational data

Cost: There is no cost in money or time. Just keep in mind that these figures reflect a lower mortality rate among married individuals — this simply means both conditions occur together, not that marriage itself extends life expectancy.

In plain terms: Over a given period, married people have a roughly 12% lower chance of dying compared to unmarried individuals, while those who have never married face a roughly 24% higher risk. However, this merely shows a correlation between marital status and mortality; it does not prove that marriage directly causes longer life. People who are healthier, wealthier, and more socially active are both more likely to marry and more likely to live longer. These statistics are primarily drawn from European and North American populations, so they can only serve as rough benchmarks for China.

Benefit: One meta-analysis of older adults pooled results from multiple studies, covering 53 comparisons and over 250,000 participants. It found that the relative risk of all-cause mortality for married versus unmarried individuals was RR 0.88, with a 95% confidence interval of 0.85–0.91. In other words, married people had a roughly 12% lower probability of dying during the study period. Among widowed individuals, this figure rose to 1.11; for divorced or separated persons, it was 1.16; and for those never married, it was 1.11 — indicating respective increases of about 11%, 16%, and 11% in mortality risk. No significant gender differences emerged. Under the most conservative estimates, the RR still came out at 0.94, reflecting a reduction of only around 6%. Another meta-analysis compared never-married individuals with married ones, drawing on 95 separate studies and over 500 million participants. It reported a hazard ratio of 1.24 (95% CI 1.19–1.30), meaning unmarried people faced roughly 24% higher mortality risk over the same timeframe; this gap narrowed with age. A further gender-specific meta-analysis examined 21 studies involving more than 7,890,000 individuals: across both sexes, unmarried status correlated with higher rates of overall mortality, cancer-related death, and cardiovascular death. Among men, the disparity was especially pronounced for cardiovascular and overall mortality; unmarried men also faced a 31% higher risk of stroke and a 9% higher risk of all-cause death compared to unmarried women.

Evidence grade: A (controversial)

Sources: Manzoli L, et al. (2007). Marital status and mortality in the elderly: a systematic review and meta-analysis. Soc Sci Med 64:77–94. <https://doi.org/10.1016/j.socscimed.2006.08.031>; Roelfs DJ, et al. (2011). The rising relative risk of mortality for singles: meta-analysis and meta-regression. Am J Epidemiol 174(4):379–389. <https://doi.org/10.1093/aje/kwr111>; Wang Y, et al. (2020). 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. Glob Health Res Policy 5:4. <https://doi.org/10.1186/s41256-020-00133-8>

Notes: The controversy stems from the fact that married individuals tend to be healthier, wealthier, and more socially engaged — factors that independently contribute to longer life. All three meta-analyses relied on observational data collected from existing populations; no controlled experiments or randomized groups were used. The authors themselves acknowledged potential publication bias and methodological limitations. Roelfs also noted that studies employing more rigorous methods tended to report smaller differences between marital groups. Since these figures are largely derived from Western populations, they can only be used as rough indicators for Chinese contexts.