Background Knee osteoarthritis (OA) is one of the leading causes of disability worldwide. The prevalence of knee OA is higher in Chinese than Caucasian subjects, despite the lower body mass index in Chinese populations.1,2 Among other Asian ethnicities, the prevalence of knee OA may also be high, and the prevalence of knee OA in the multi-ethnic Singapore population is still unknown.
Objectives Our study aimed to estimate the prevalence of knee OA in the general population of Singapore, using a validated questionnaire consisting of 3 knee OA symptoms or 1 symptom and a physician diagnosis (sensitivity of 54%, specificity of 87%).3
Methods We recruited a subset of subjects from the National Health Surveillance Survey (NHSS) 2013 who provided telephone numbers. Consenting subjects were invited to complete a validated screening questionnaire by mail.3 If no response was received after 4 weeks, the subjects were interviewed by telephone to complete the screening questionnaire. The national prevalence of knee OA was estimated by accounting for the proportion of subjects who provided telephone numbers; it was weighted to the gender, age, and ethnic distribution profiles of the final respondents.
Results From the NHSS cohort of respondents (n=9,631 subjects), 4,633 (48.1%) subjects provided telephone numbers. A total of 3,364 sets of screening questionnaires were completed, out of 4,557 sent (response rate=73.8%). The demographic profile of the responders were not significantly different from the original NHSS cohort profile. The estimated national prevalence of knee OA was 11%. Women (13.1%) had a higher prevalence of knee OA than men (8.8%). The prevalence of knee OA increased with age and was 19.7% for age ≥60 years old, compared to 8.6% for age 18–59 years old. Across the different ethnic groups, knee OA was more prevalent among Indian (20.5%), followed by Malay (17.7%), and Chinese (9.3%).
Conclusions Using a validated screening questionnaire, we estimated the national prevalence of knee OA in the multi-ethnic Singapore population. Indian and Malay had higher prevalence of knee OA, which could be attributed to the higher prevalence of obesity among these ethnic groups as compared to Chinese.4
Zhang, Y., et al., Comparison of the prevalence of knee osteoarthritis between the elderly Chinese population in Beijing and whites in the United States: The Beijing Osteoarthritis Study. Arthritis Rheum, 2001. 44(9): p. 2065–2071.
Felson, D., et al., High prevalence of lateral knee osteoarthritis in Beijing Chinese compared with Framingham Caucasian subjects. Arthritis Rheum, 2002. 46(5): p. 1217–22.
Leung, Y., et al., Evaluation of three screening questionnaires for use in identifying symptomatic knee osteoarthritis in the general population. Ann Rheum Dis, 2013. 72: p. A975.
MOH, National Health Survey. 2010: Singapore.
Disclosure of Interest None declared