VALIDATION DATA

In a study involving people undergoing joint replacement surgery for arthritis, good internal consistency was reported for the WHOQOL-BREF, with all domains demonstrating a Cronbach's α of 0.70 or more. Only one study, which involved 214 patients with rheumatoid arthritis, reported poor internal consistency for the social relationships domain, with an α of 0.64.

More broadly, the WHOQOL-BREF has been shown to have good internal consistency in the community-based samples. A study involving 4628 people in the United Kingdom with and without a range of health conditions (including arthritis) also reported high internal consistency (Cronbach's α = 0.92). Similarly, a cross-sectional Brazilian study of quality of life involving 278 older people (mean age of 64 years) reported an overall Cronbach's α of 0.83. Another study assessing the psychometric properties of WHOQOL-BREF in 1316 Singaporean adults reported a Cronbach's α of 0.70 or more for all domains

Evidence of test-retest reliability for the WHOQOL-BREF among people with rheumatic conditions is limited, with only one study involving patients with rheumatoid arthritis. This study found that the WHOQOL-BREF had good temporal stability (mean test-retest interval of 3.5 days), as indicated by high ICCs for the physical health (ICC = 0.79), psychological (ICC = 0.86), social relationships (ICC = 0.91), and environment (ICC = 0.72) domains. Similarly, good test-retest reliability of the WHOQOL-BREF has been demonstrated for other chronic conditions. In a study of 199 individuals with traumatic brain injury, test-retest reliability was acceptable across the physical health (ICC = 0.86), psychological (ICC = 0.95), social relationships (ICC = 0.74), and environment (ICC = 0.90) domains over a 2-week interval. In another study involving 39 individuals with depression, excellent test-retest reliability (1-week test-retest interval) was reported, with an ICC score of 0.92 for the overall score based on 26 items.

The WHOQOL-BREF has good face validity for the assessment of quality of life in rheumatic conditions given its ability to broadly address the physical health, psychological, social relationships, and environmental aspects of health. Content validity is also supported by the relatively low prevalence of floor and ceiling effects, highlighting the questionnaire's ability to capture a wide continuum of health states.

In studies comparing quality of life between those with musculoskeletal disease and healthy populations, WHOQOL-BREF scores differentiated between the two groups. A prospective study of 76 patients with adhesive capsulitis and 72 healthy controls also found between-group differences in the WHOQOL-BREF physical health, psychological, and environmental domain scores. Other studies also support known-groups validity of the WHOQOL-BREF, with significantly higher quality of life scores reported for patients in relatively good health versus those in poorer health.