Background Survey data provide important information on the prevalence of chronic conditions across different areas and population groups. In Canada, large national surveys routinely ask about physician-diagnosed arthritis. However, population data on osteoarthritis (OA) are limited, and there is virtually no information on self-reported, physician-diagnosed osteoarthritis of specific joints.
Objectives The purpose of this study was to determine the prevalence of joint symptoms and self-reported, health professional diagnosed OA of different joints in a representative community sample of adults in the province of British Columbia (BC), Canada.
Methods We carried out a mixed-method (mail and online) survey. A random sample of households was selected from a list of all residential addresses in BC. A variety of incentives were used to maximize response rates. One randomly selected person age 18+ per household was asked to complete the survey. We asked about joint pain or discomfort (using a homunculus) and a health professional diagnosis of OA in the knee, hip, hand, foot/ankle, lower back, and neck. In addition, demographic, general health, and healthcare utilization information was collected.
Results Survey invitation letters were mailed to 7759 households and 2233 individuals completed an online (1778, 79.6%) or mailed (455, 20.4%) questionnaire. Of those, 45.8% were men, 38.8% were age 60+ and 19.9% were obese (BMI 30+). Joint pain/discomfort was reported by the following proportions of respondents: lower back - 48.8%, neck - 38.7%, knee - 34.7%, foot/ankle - 30.8%, hand - 30.5%, and hip - 24.2%. Joint pain/discomfort in the hand, hip and knee was more common on the right side, while foot pain was symmetrically distributed. Both sides were most often affected in the hands (51%) and least often in the hips (39%) and knees (40%). The most common site of OA was the knee - 10.1%, followed by lower back - 8.5%, neck - 5.5%, hand - 5.4%, hip - 4.2%, and foot - 3.1%. OA prevalence in any joint was 20.9% (15.7% if back/neck is excluded). OA prevalence was 12.2% when the diagnosis was restricted to those reporting any arthritis diagnosed by a health professional. The average age of OA diagnosis ranged from 52.4 years for the neck to 56.6 for the hip. Among those with OA, 43.4% (9.1% of all respondents) reported OA in multiple joint sites; 4.9% had OA in two sites, 2.4% in 3, and 1.7% in 4 or more. OA in one site was a strong predictor of OA in other sites. The strongest relationship was between hand and foot OA (odds ratio 25). In a multivariable logistic model older age and female sex were associated with higher OA prevalence, while education and income were not.
Conclusions This is one of the first population surveys in Canada to report joint-specific prevalence of pain and self-reported health professional diagnosed OA in a large, geographically defined population. The most common OA site was the knee, but OA in the hand, hip and foot/ankle was also common. More than 40% had OA in multiple sites. Prevalence of OA in population surveys may be underestimated if the question about OA is asked only of those who report any arthritis.
Disclosure of Interest : None declared