Role of Newman's classification in predicting outcomes in patients with crystal arthritis

The aim of the study was to evaluate the utility of Newman's classification in predicting outcomes in patients presenting with crystal arthritis.

Between January and December 2009, all patients who presented to our institution with acute crystal arthritis and were investigated with microbiological assessment of their synovial fluid were included in the study. Patients were divided into two groups depending on the fulfilment of Newman's criteria for culture-negative septic arthritis. Group 1 included patients that fulfilled Newman's B criteria. Group 2 included patients that fulfilled Newman's C criteria. A database looking at the demographics, mode of presentation, investigations, treatment and outcomes was then established and the results compared between the two groups.

A total of 58 patients were identified (group 1: n = 13; group 2: n = 45). The average age was 71 years (range 33-96). The joint most commonly involved was the knee followed by the wrist. Clinical findings at presentation were comparable in both groups; however, WBC and C-reactive protein (CRP) were more likely to be raised in group 1. Although most patients in group 1 were treated with antibiotics (62%) there was still a higher rate of morbidity, greater use of supportive therapy and a longer hospital stay (22.3 days, SD 17.4) in comparison with group 2, where most patients were treated by observation only (76%, mean hospital stay 3.5 days, SD ± 4.4). The difference in length of hospital stay was statistically significant (p < 0.0001).

Newman's criteria are a good indicator for prognosis in patients with crystal arthritis. However, the presence of crystals in an acutely inflamed joint does not exclude the need for supportive therapy and long hospital stay even in the absence of positive synovial fluid culture.