Relative Income Deprivation and All-Cause Mortality in Japan: Do Life Priorities Matter?

Background/purpose: Relative deprivation (RD) is proposed to affect health through psychosocial stress stemming from upward social comparisons. This study hypothesized that prioritizing values, such as social engagement and personal growth (as opposed to prioritizing work), would inoculate against the toxic effects of upward social comparisons.

Methods: Prospective data of 9,533 subjects (4,475 men and 5,058 women) participating in the Komo-Ise study answering a baseline questionnaire in 1993 and a follow-up survey in 2000 were analyzed. Associations between RD-using Yitzhaki Index (YI) and Income Rank (IR)-and mortality were evaluated using Cox proportional-hazard regression models. At follow-up, people were also asked about what they prioritized in life: work, social engagement, or personal growth.

Results: 1,168 deaths (761 men and 407 women) occurred during follow-up (to the end of 2011). Controlling for sociodemographic factors, the hazard ratio (HR) for mortality was 1.22 (95% confidence interval [CI] = 1.08-1.38) per a standard deviation (SD) increase in YI and 1.18 (95% CI = 1.03-1.35) per an SD decrease in IR. Life priorities (LP) were not statistically significantly associated with mortality. In women, the interaction between LP and YI was statistically significant. In fully adjusted models, women who endorsed only work as very important in their lives had a 2.66 (95% CI = 1.23-5.77) times higher HR for mortality per SD increase in YI compared to women who valued social engagement/personal growth. An interaction between LP and RD was not found in men.

Conclusions: Increased relative income deprivation was associated with a higher risk of all-cause mortality independently of absolute income. Focusing on social engagement/personal growth (as opposed to work) appears to inoculate women against the toxic effects of relative deprivation.