OBJECTIVES

People with osteoarthritis (OA) are likely to have comorbidities during the course of illness, which may have important consequences for their health-related quality of life (HRQoL). The objective of this study is to explore the impact of total number of comorbidities and individual comorbidities on health state utilities (HSUs) and individual health dimensions of Independent Living, Social Relationships, Physical Sense and Psychological Wellness of older Australians with OA.

METHODS

OA participants from the Tasmanian Older Adult Cohort (TASOAC) aged 50-80 years, with data on HRQoL and comorbidities were included. Data were collected at baseline (n=398), 2.5 years (n=304), 5 years (n=269) and 10 years (n=191). HRQoL was assessed using the Assessment of Quality of Life-4 Dimensions (AQoL-4D) instrument. Associations between comorbidities and HSUs and individual dimensional scores were analysed using mixed linear regression model adjusted for age, sex, body mass index, education, employment status and disability.

RESULTS

A statistically significant and clinically important difference of -0.07 (95% confidential interval [95% CI] -0.11,-0.03) units was seen between the mean HSUs of no comorbidity OA participants and those with >3 comorbidities. Higher number of comorbidities was associated with lower Independent Living and Psychological Wellness scores, with an Independent Living score difference of -0.05 (95%CI: -0.07,-0.02) and Psychological Wellness score difference of -0.04 (95%CI: -0.06,-0.02) between no comorbidity and >3 comorbidities. No evidence of an impact of comorbidities on the health dimensions of Social Relationship and Physical Sense was found. Of the individual comorbidities, asthma and heart attack were negatively associated with HSUs; asthma, diabetes, heart attack and hypertension with Independent Living; and asthma and osteoporosis with Psychological Wellness.

CONCLUSIONS

Comorbidities negatively impacted HSUs of OA participants. Independent Living and Psychological Wellness were the most highly impacted individual health dimensions. Optimal management of influential individual comorbidities may improve the HRQoL of people with OA.