Physical function and self-efficacy - Important aspects of health-related quality of life in individuals with hip osteoarthritis

Introduction: Osteoarthritis (OA) is the most common form of arthritis and the most common chronic joint disease in individuals over the age of 65 years. The condition is often associated with significant pain, stiffness, fatigue, and has a strong impact on physical function, mobility and quality of life. Objectives: The aim of the present study was to investigate the associations between health-related quality of life (HRQL), physical function and self-efficacy (the sense of being able to perform specific tasks), in individuals with X-ray-verified hip OA. The aim was also to determine factors explaining good perceived HRQL. Participants: Eighty-nine individuals with X-ray-verified hip OA in the age group 40-75 years participated in this study. The study sample predominantly consisted of females, n = 61 (69%), and the mean age was 62.5 years, range 39-76. Main outcome measures: For assessment of HRQL, the Medical Outcomes Study 36-Item Short Form Health Survey (SF-36), which is divided into the Physical Component Scale (PCS) and the Mental Component Scale (MCS), was used. Physical function was measured with one self-recorded instrument, the Hip Osteoarthritis Outcomes Score (HOOS Swedish version L.K 1.1), and two instruments using observation - the Body Awareness Scale - Movement Quality (BAS-MQ) and the Six Minute Walk Test (6MWT). Self-efficacy was evaluated using the Arthritis Self-Efficacy Scale (ASES). Results: The data indicated that HRQL (SF-36 PCS) had a significant correlation with both observed physical function and self-reported physical function. SF-36 PCS correlated significantly to all five subscales in HOOS, two of three subscales in BAS-MQ, 6MWT and all three subscales in ASES. Three subscales in HOOS, one subscale in ASES and the 6MWT together explained 58% (R-2) of the variance in SF-36 PCS. Conclusion: The results of the current study indicated that good physical ability and good self-efficacy are important for HRQL in subjects with hip OA. This knowledge ought to influence future rehabilitation strategies. The treatment strategies for individuals with OA ought to be directed not only to the symptoms of the disease, but also to the individual's possibilities of gaining perceived control over the consequences of the disease including the HRQL.