Serum Cartilage Oligomeric Matrix Protein: Tool for early diagnosis and grading of severity of primary knee osteoarthritis

Context: With increasing elderly population there is increasing prevalence of primary degenerative knee osteoarthritis (KOA), but specific and sensitive tests to diagnose and ascertain the severity of such ailments are lacking. Bone and cartilage biomarkers, like serum Cartilage Oligomeric Matrix Protein (sCOMP) level show changes much before than clinical or radiological changes. So far it has not been used in clinical practice as the diagnostic range of serum COMP levels have not been defined. Aims: The aim of present study was to assess the efficacy of sCOMP levels in diagnosis of different grades of severity of primary knee osteoarthritis. Settings and design: A hospital based prospective case control study recruiting 100 cases and 50 controls. Methods and material: All subjects were examined clinically and further evaluated by plain radiography and serum COMP values were estimated by enzyme linked immune-sorbent assay (ELISA). Multiple statistical tools were used to analyse the results. Results: The difference between sCOMP values among cases and controls was statistically significant (t=21.774; p<0.001). The mean sCOMP also shows a gradual increase with increase in severity of knee osteoarthritis. [F=38.940; p<0.001 (ANOVA)]. Conclusions: The serum COMP levels can be used to diagnose normal and diseased individual and also assess different grades of severity of knee osteoarthritis. We suggest cut off levels of sCOMP of 652.5 nano gram/deci litre (ng/dl) between normal and diseased individual, of 801.5 ng/dl between mild and moderate grade of osteoarthritis, and of 1100.5 ng/dl between moderate and severe grade of knee Osteoarthritis (KOA).