Mazzuca SA et al. (2006) Associations between joint space narrowing and molecular markers of collagen and proteoglycan turnover in patients with knee osteoarthritis. J Rheumatol 33: 1147–1151

The search for a reliable biomarker of osteoarthritis progression has been ongoing for over 20 years. In a new study, none of the biomarkers investigated predicted progression of joint-space narrowing (JSN) over a 30-month period. There were, however, indications that one biomarker should be studied further.

In a previous trial of doxycycline, plasma samples were taken from 431 patients at baseline and at 6-month intervals for 30 months. Mazzuca et al. selected 60 participants from this trial who had shown osteoarthritis progression in radiographic assessments, and 60 participants who had not. They compared the concentrations of several biomarkers (i.e. the proteoglycan aggrecan epitope CS846; markers for collagenase cleavage of type II collagen, collagenase cleavage of type I and II collagens, and type II collagen synthesis; and the ratio of collagenase cleavage of type II collagen to type II collagen synthesis) in all the plasma samples of the two groups.

Mazzuca et al. did not find any strong evidence that these biomarkers predicted osteoarthritis progression. Neither baseline nor serial biomarker levels predicted JSN progression over the entire 30-month study period; however, an association was noted between CS846 and JSN progression in the knee over the first 16 months (P<0.01). The authors note that their cohort comprised patients from the extreme ends of the JSN spectrum, and recommend that further studies explore the connection between CS846 and JSN progression in a more-representative population.