Area-level and individual-level socio-economic differences in health-related quality of life trajectories: Results from a 10-year longitudinal stroke study

Background: We examined area-level (aSES) and individual-level (iSES) socio-eco-nomic status on trajectories of HRQoL to 10 years following stroke. Methods: Participants with strokes between 1/5/1996 and 30/4/1999 completed the Assessment of Quality of Life instrument (AQoL, range:-0.04 [worse than death] to 0 [death] to 1 [full health]) at >one of 3month, 6-month, 1-year, 2-year, 3-year, 4 -year, 5-year, 7-year and 10-year interviews after stroke. Sociodemographic and health information were collected at baseline. We derived aSES from postcode using the Australian Socio-Economic Indexes For Area (2006) (categories: high, medium, low), and iSES from lifetime occupation (categories: non-manual, manual). Multi -variable linear mixed effects modelling was used to estimate trajectories of HRQoL over 10 years, by aSES and iSES, adjusting for age, sex, cardiovascular disease, smoking, diabetes, stroke severity, stroke type, and the time influence on age and health conditions. Results: Of 1,686 participants enrolled, we excluded 239 with 'possible' stroke and 284 with missing iSES. Among the remaining 1,163 partici-pants, 1,123 (96.6%) had AQoL assessed at >3 timepoints. In multivariable analysis, over time, people in the medium aSES group had mean 0.02 (95% CI-0.06, 0.02) greater reduction in AQoL score, and people in the low aSES group had mean 0.04 (95% CI,-0.07,-0.001) greater reduction, than those in the high aSES group. Manual workers had an average 0.04 (95% CI,-0.07,-0.01) greater reduction in AQoL score over time than non-manual workers. Conclusions: Over time, HRQoL declines in all people with stroke, declining most rapidly in lower SES groups.