Secretory phospholipase A(2) as an index of disease activity in rheumatoid arthritis. Prospective double blind study of 212 patients

Objective, A limited retrospective study of patients with rheumatoid arthritis (RA) found that serum secreted phospholipase A(2) (sPLA(2)) activity correlates with disease activity (J Rheumatol 1988; 15:1351-5). To assess the strength of this relationship we investigated prospectively 212 patients with RA using a double blind approach. Methods. 212 patients who fulfilled the 1987 ACR criteria for RA had 420 clinical and laboratory assessments. 65 patients were assessed on one occasion and 147 on multiple occasions (a mean of 2.41 visits/patient). sPLA(2) was tested by an independent investigator. Results. sPLA(2) activity assessed as a dichotomous variable (less or more than mean +/- 2 SD) correlated highly (p < 0.005) with Lansbury index, number of effusions, number of damaged joints, erythrocyte sedimentation rate (ESR), platelet count, and low hemoglobin. Univariate and multivariate regression analyses showed significant correlations with Lansbury index, active and effused joints, hemoglobin, platelet count, and ESR. The best correlation was observed in a multivariate model that included Lansbury index, ESR, and platelet count (r = 0.60). Analysis of longitudinal changes in sPLA(2) activity in 147 patients assessed more than once showed that sPLA(2) correlates significantly with Lansbury index, active and effused joints, and hemoglobin. Conclusion. Serum sPLA(2) activity correlates significantly with Lansbury index, active and effused joints, ESR, platelet count, and hemoglobin. Thus, sPLA(2) can serve as an index of disease activity in RA.