Association Between Life Purpose and Mortality Among US Adults Older Than 50 Years

Abstract

Importance: A growing body of literature suggests that having a strong sense of purpose in life leads to improvements in both physical and mental health and enhances overall quality of life. There are interventions available to influence life purpose; thus, understanding the association of life purpose with mortality is critical.

Objective: To evaluate whether an association exists between life purpose and all-cause or cause-specific mortality among older adults in the United States.

Design, setting, and participants: The Health and Retirement Study (HRS) is a national cohort study of US adults older than 50 years. Adults between the ages of 51 to 61 were enrolled in the HRS, and their spouses or partners were enrolled regardless of age. Initially, individuals born between 1931 and 1941 were enrolled starting in 1992, but subsequent cohort enrichment was carried out. The present prospective cohort study sample was drawn from 8419 HRS participants who were older than 50 years and who had filled out a psychological questionnaire during the HRS 2006 interview period. Of these, 1142 nonresponders with incomplete life purpose data, 163 respondents with missing sample weights, 81 participants lost to follow-up, 1 participant with an incorrect survival time, and 47 participants with missing information on covariates were excluded. The final sample for analysis was 6985 individuals. Data analyses were conducted between June 5, 2018, and April 22, 2019.

Exposures: Purpose in life was assessed for the 2006 interview period with a 7-item questionnaire from the modified Ryff and Keyes Scales of Psychological Well-being evaluation using a Likert scale ranging from 1 to 6, with higher scores indicating greater purpose in life; for all-cause and cause-specific mortality analyses, 5 categories of life purpose scores were used (1.00-2.99, 3.00-3.99, 4.00-4.99, 5.00-5.99, and 6.00).

Main outcomes and measures: All-cause and cause-specific mortality were assessed between 2006 and 2010. Weighted Cox proportional hazards models were used to evaluate life purpose and mortality.

Results: Of 6985 individuals included in the analysis, 4016 (57.5%) were women, the mean (SD) age of all participants was 68.6 (9.8) years, and the mean (SD) survival time for decedents was 31.21 (15.42) months (range, 1.00-71.00 months). Life purpose was significantly associated with all-cause mortality in the HRS (hazard ratio, 2.43; 95% CI, 1.57-3.75, comparing those in the lowest life purpose category with those in the highest life purpose category). Some significant cause-specific mortality associations with life purpose were also observed (heart, circulatory, and blood conditions: hazard ratio, 2.66; 95% CI, 1.62-4.38).

Conclusions and relevance: This study's results indicated that stronger purpose in life was associated with decreased mortality. Purposeful living may have health benefits. Future research should focus on evaluating the association of life purpose interventions with health outcomes, including mortality. In addition, understanding potential biological mechanisms through which life purpose may influence health outcomes would be valuable.

Figure.. Survival Curves Illustrating the Association Between Life Purpose and Mortality

Survival curves are adjusted for age, sex, educational level, race/ethnicity, marital status, smoking status, frequency of physical activity, alcohol consumption, body mass index, functional status, 1 or more chronic health conditions, depression, anxiety, cynical hostility, negative affect optimism, positive affect, and social participation. Adjusted survival curves are constructed by first generating a pseudopopulation based on study population characteristics. For each life purpose score category, a survival curve is estimated for this pseudopopulation based on the fitted Cox proportional hazards model presented in Table 2 assuming that all participants fall into that specific life purpose score category. This figure illustrates the relationship between life purpose and mortality on a covariate balanced pseudopopulation, with those in the lowest category (1.00-2.99) having significantly worse survival than those in the highest life purpose category (6.00).