Low serum level of COMP, a cartilage turnover marker, predicts rapid and high ACR70 response to adalimumab therapy in rheumatoid arthritis.

The aim of this study was to evaluate serum biomarkers, used in clinical routine, to predict the American College of Rheumatology (ACR) response to long-term anti-TNF alpha treatment (adalimumab). Sera from 29 consecutive rheumatoid arthritis patients were analysed for anti-cyclic citrullinated peptide (anti-CCP), cartilage oligomeric matrix protein (COMP) and IgM and IgA RFs (class-specific rheumatoid factors) at the start of treatment with adalimumab and after 3, 6 and 12 months. The response to the therapy was evaluated by ACR 20, 50, 70 and by DAS 28 scores. The mean serum COMP level of the population did not change after treatment. However, patients with low serum COMP levels (<10 U/l) at baseline showed a significant (p<0.02) higher ACR70 response (>50%) within 3 months, and also at 6 months, than patients with higher COMP values (ACR70<20%). This was also reflected by significantly higher decrease in DAS score at 3 (p<0.02) and 6 months (p<0.01) treatments. The IgM RF titre decreased significantly (p=0.02) after the therapy, but the percentage of serum positivity for anti-CCP and IgA/IgM RF did not change. No significant correlation was shown between serum COMP levels and C-reactive protein/erythrocyte sedimentation rate during the follow-up. Neither were any correlations shown between ACR/DAS 28 scores and anti-CCP, Ig M/IgA RFs. Our data indicate that low (<10 U/l) serum COMP before starting anti-TNF alpha treatment predicts a rapid (within 3 months) and high ACR70 response compared to RA patients with higher COMP values. This might reflect different mechanisms in the cartilage process in the RA disease at that time of treatment with different therapeutic sensitivity to anti-TNF alpha treatment.

Diff Quik staining method for detection and identification of monosodium urate and calcium pyrophosphate crystals in synovial fluids.

OBJECTIVE: To evaluate whether the Diff Quik (DQ) staining method might prove useful in identifying monosodium urate (MSU) and calcium pyrophosphate dihydrate (CPPD) crystals on permanent mounted stained slides. METHODS: 27 synovial fluid (SF) samples obtained from the knees of 21 patients with acute CPPD disease and 6 with acute gout were studied. Wet analysis for crystal detection and identification was performed within one hour of joint aspiration. In addition, 16 inflammatory synovial effusions obtained from patients with knee arthritis induced by non-crystalline inflammatory diseases were studied. For each SF, a DQ stained slide was analysed by two of the authors trained in SF analysis. The observers were blinded to the type of crystals present in the SF. Each slide was analysed by compensated polarised as well as transmitted light microscopy. An SF was considered positive if intracellular and/or extracellular crystals were clearly identified. In addition, the observer was asked to identify the type of the crystals using compensated polarised light microscopy. Sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) of the DQ staining method were determined. RESULTS: 51 true positive and 28 true negative cases were correctly classified (39 CPPD samples, 12 MSU samples, 28 samples of crystal unrelated arthropathies). Overall, four false positive and three false negative cases were reported. In all the false positive cases, extracellular CPPD crystals were erroneously identified, whereas CPPD crystals present in the SF were not identified in the three false negative cases. All MSU specimens were correctly diagnosed. The overall specificity, sensitivity, and accuracy using DQ stained slides for crystal confirmation were respectively 87.5%, 94.4%, and 91.9%. The PPV was 92.7% and the NPV 90.3%. In particular, the specificity, sensitivity, and accuracy for CPPD detection were 90.9%, 92.9%, and 91.9%, with a PPV of 90.7 and an NPV of 93.0%. All the MSU specimens were correctly identified, providing 100% sensitivity, specificity, accuracy, PPV, and NPV. CONCLUSIONS: Stained preparations of SF, including DQ stained smears, could provide a useful tool for delayed SF analysis suitable for quality controls, including cytological examination and crystals detection and identification.

[Diff-Quik(R) staining method for detection and identification of monosodium urate and calcium pyrophosphate crystals in synovial fluids] / La colorazione con Diff-Quik(R) per l'identificazione di cristalli di urato monosodico e pirofosfato di calcio diidrato nel liquido sinoviale.

The aim of this study was to evaluate whether DQ could prove useful to identify monosodium urate (MSU) and calcium pyrophosphate dehydrate (CPPD) crystals on permanent mounted stained slides. To this end, we studied 27 synovial fluid (SF) samples obtained from the knees of patients with the pseudogout (n=21) and acute gouty arthritis (n=6). Wet analysis for crystal detection and identification was performed within one hour of joint aspiration. In addition, we studied 16 inflammatory synovial effusions obtained from patients with knee arthritis not induced by crystals. For each SF, DQ stained slides were analyzed by 2 experienced doctors in SF analysis. The observers were blinded to the type of crystal present in the SF. Each slide was analyzed by compensated polarized and transmitted light microscopy. SF was considered positive if intracellular and/or extracellular crystals were clearly identified. In addition, the observers were asked to identify the type of the crystals using compensated polarized light microscopy. Sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) of the DQ staining method were determined. 51 true positive and 28 true negative specimens were correctly classified (39 CPPD samples, 12 MSU samples, and 28 samples of crystals-unrelated arthropathies). All MSU specimens were correctly diagnosed.