The burden of osteoarthritis: self-reported severity in the KHOALA population-based cohort.

OBJECTIVES: Lay descriptions of mild, moderate and severe disease states have been utilized in Global Burden of Disease studies in the calculation of years lived with disability, and may be a useful brief starting point for clinical care. The primary aims of this study were to estimate the proportion of an OA cohort within each severity level, and to assess the validity of lay descriptions of OA.

METHODS: During 2014 to 2016, participants in the KHOALA population-based cohort completed questionnaires including pain, function, and quality of life, in addition to indicating which of the lay descriptions devised for presenting to populations in GBD2010 they felt best described their current condition.

RESULTS: 569 participants comprising 152 with hip OA, 384 knee OA and 33 with both hip+knee OA participated. 10% of hip OA and 17% of knee OA participants classified themselves as having severe OA, a considerably higher proportion than the 2% reported for high-income countries in GBD2010.The lay descriptions showed significant convergent and divergent validity: pain, function and stiffness scores increased as the rating of severity increased, with a significant trend for EQ5D and EUROQOL VAS to decline, also indicating worse health state, as level of severity increased.

CONCLUSION: Lay descriptions of levels of severity are understandable by participants and show convergent validity with standardized measure of physical and functional outcomes. The proportion of people with OA who align themselves with the severe category is considerably larger than that used in GBD estimates to estimate the impact of OA.