Associations between illness duration and health-related quality of life in specified mental and physical chronic health conditions: results from a population-based survey

We compared health-related quality of life (HRQOL) in incident (>1 year since diagnosis), mid-term (> 1-5 years since diagnosis), and long-term (> 5 years since diagnosis) cases of mental and physical chronic illness with the general population and assessed the modifying effects of age and gender on the association between HRQOL and illness duration. Data from the 2007 Australian National Health and Mental Wellbeing Survey were used. HRQOL was captured by the Assessment of Quality of Life Scale 4D. Multivariable linear regression analyses compared HRQOL of individuals with different duration of illnesses with those who did not have the condition of interest. The 8841 survey respondents were aged 16-85 years (median 43 years, 50.3% female). For the overall sample, worse HRQOL was associated with incident (P = 0.049) and mid-term (P = 0.036) stroke and long-term depression (P < 0.001) and anxiety (P = 0.001). Age had moderating effect on the associations between HRQOL and duration of asthma (P < 0.001), arthritis (P = 0.001), diabetes (P = 0.004), stroke (P = 0.009), depression (P < 0.001), bipolar disorder (P < 0.001), and anxiety (P < 0.001), but not heart disease (P = 0.102). In older ages, the greatest loss in HRQOL was associated with incident asthma, depression, and bipolar disorder. In younger ages, the greatest loss in HRQOL was associated with arthritis (any duration) and incident diabetes and anxiety. Additionally, gender moderated the association between HRQOL and arthritis, with worse HRQOL among men with incident arthritis (P = 0.047). Loss of HRQOL associated with longer duration of chronic illness is most apparent in stroke and mental illness and differs between age groups.