Length of hospital stay is inversely associated with socioeconomic status (SES). It is less clear whether socioeconomic disparities in numbers of hospital days diverge or converge with age.
Longitudinal linked Finnish registry data (1988–2007) from 137,653 men and women aged 50–79 years at the end of 1987 were used. Trajectories of annual total hospital days by education, household income, and occupational class were estimated using negative binomial models.
Men and women with higher education, household income, and occupational class had fewer hospital days in 1988 than those with lower SES. Hospital days increased between 1988 and 2007. For some age groups, higher SES was associated with a faster annual rate of increase, resulting in narrowing rate ratios of hospital days between SES groups (relative differences); the rate ratios remained stable for other groups. Absolute SES differences in numbers of hospital days appeared to diverge with age among those aged 50–69 years at baseline, but converge among those aged 70–79 years at baseline.
The hypotheses that socioeconomic disparities in health diverge or converge with age may not be mutually exclusive; we demonstrated convergence/maintenance in relative differences for all age groups, but divergence or convergence in absolute differences depending on age.