Co-morbidities of Osteoarthritis Knee Patients

Keith K. W. Chan*, Allen H. Y. Ngai, Andrew K. K. Ip, Stanley H. K. Lam, Mark W. W. Lai

Hong Kong Med J, Volume 15, 2009, 31-38


Objectives: To study the co-morbidity pattern of patients suffering from Osteoarthritis (OA) of knee in general practice

Methods: A cross-sectional study using semi-instructed questionnaire survey conducted in two general practice clinics in Hong Kong

Results: All patients seen at the 2 clinics for knee pain. Those with knee pains were screened for OA knee according to the diagnostic criteria of OA knee established by the American College of Rheumatology. A total of 455 patients fulfilled the criteria were included in the study. 56.3% of them had knee pain plus > 3 other diagnostic criteria. One point to note was that 95.4% of OA knee patients did not have signs of inflammation. The mean age was 53.6 years (SD 13.18). 69.7% was female. 68.1% of them had BMI ≥23 with a mean BMI of 24.54 (SD 3.72). 78% of patients had at least one musculoskeletal (MSK) co-morbidity and 82% of patients had at least one non-MSK co-morbidity. Overall, the patients had on average 3.16 co-morbidities, of which, 1.71 were MSK co-morbidities and 1.45 were non-MSK. Problems from back, upper limbs, neck and lower limbs were the 4 most common MSK co-morbidities, of which neck problems were significantly higher among the younger patient group (<55 years) (OR for older to younger age group 0.62; 95% CI 0.41 to 0.92). For non-MSK co-morbidities, the top 4 categories were cardiovascular (33.0%), gastrointestinal (29.0%), respiratory (27.0%) and endocrine (21.3%), of which cardiovascular diseases, (OR 8.76; 95% CI 5.61 to 13.69), endocrine problems (e.g. diabetes) (OR 4.56; 95% CI 2.82 to 7.37), and central nervous system diseases (e.g. stroke) (OR 12.74; 95% CI 1.58 to 102.79) were significantly higher among the older patient group (≥ 55 years).

Conclusion: The Chinese patients in our study share the same risk factors of OA knee as reported by other studies. Our OA knee patients are likely to be elderly people and have multiple concomitant health-related problems. These co-morbidities can interact with each other to produce high levels of disability e.g. the increased pain and reduced mobility from the MSK co-morbidities. Also co-morbidities can also lead to management problems e.g. drug safety issue with the presence of cardiovascular co-morbidity and the prescription of COX-2 inhibitors, gastrointestinal co-morbidity and the use of non-steroidal anti-inflammatory drugs etc. Primary care physicians should be alert with the presence of co-morbidities when managing patients with OA knee.

* Dr. Chan Kwok Wai, FHKAM (FM), FRCGP, FRACGP, FHKCFP, MMPhysMed (

Corresponding address:  Room 1201, 12/F, City Landmark I, 68 Chung On Street, Tsuen Wan.