Taxation categories for long-term care insurance premiums and mortality among elderly Japanese: a cohort study

This cohort study examined the association between taxation categories of long-term care insurance premiums and survival among elderly Japanese.

A total of 3000 participants aged 60 years or older were randomly recruited in Y City, Japan in 2002, of whom 2964 provided complete information for analysis. Information on income level, mobility status, medical status, and vital status of each participant was collected annually from 2002 to 2006. Follow-up surveys on survival were conducted until August 2007. Hazard ratios (HRs) were estimated by a Cox model, using taxation categories at baseline. In these analyses, age-adjusted and age- and mobility-adjusted models were used.

A significantly higher mortality risk was seen only in the lowest taxation category among men: as compared with men in the second highest taxation category, the HR in the lowest category was 2.53 (95% CI, 1.26-5.08, P = 0.009). This significant association between taxation category and mortality was lost after adjustment for mobility. There was no other difference in mortality among taxation categories in men or women.

The present findings only partly supported our hypothesis that taxation category is a good indicator of socioeconomic status in examining health inequalities among elderly Japanese.