Background Recently, a novel scoring system was developed for the diagnosis of gout without joint fluid analysis (1). The performance of this scoring system in the differential diagnosis between acute gout and septic arthritis has not been validated yet.
Objectives This study aimed to evaluate the diagnostic performance of this scoring system in the differential diagnosis between acute gout and septic arthritis in patients with acute monoarthritis.
Methods The medical records of 33 patients with acute gout and 27 with septic arthritis who presented as acute monoarthritis and were diagnosed at Chung-Ang University Hospital in Seoul, South Korea and Dongguk University Hospital in Goyang, South Korea from 2007 to 2012 were reviewed. Patients with podagra were excluded. All gout patients were MSU positive and all septic arthritis patients had positive results of bacterial culture. The diagnostic scoring system (1) gives different scores to several clinical criteria as follows: 2 to male sex, 2 to previous patient reported arthritis attack, 0.5 to onset within one day, 1 to joint redness, 2.5 to 1st MTP involvement, 1.5 to hypertension or at least one cardiovasacular disease and 3.5 to serum uric acid greater than 5.88 mg/dL. The probability of gout is high when the sum of the score is ≥ 8, intermediate when between 4 and 8 and low when ≤ 4. Patients were classified to one of each probability groups according to the scores they got.
Results Both patient groups were similar in age (55.6±21 vs. 58.4±20.2 years). However, patients with acute gouty arthritis were more likely to be male (90.9% vs. 59.2%), had shorter duration of onset (1.54±1.22 vs.2.92±2.0 days, p=0.004), lower levels of ESR (38.3±73.7mm/hr p=0.001), CRP(7.8±7.0 vs.13.6±9.9 mg/dL, p=0.01), WBC count (9813±2122 vs. 12502±5060/m3, p=0.021) and synovial fluid WBC count (37295±26998 vs. 63210±41211/m3, p=0.014) and had higher levels of serum uric acid compared to those with septic arthritis (7.88±1.8 vs. 5.13±1.7 mg/dL, p<0.001). The sum of scores in patients with acute gout was significantly higher than those of patients with septic arthritis (7.8 ± 1.59 vs. 3.4 ± 2.3, p<0.001). In 33 patients with acute gout, the numbers of patients classified to each of the 3 probability groups were 22, 11 and 0 (high, intermediate and low probability, respectively). However, in 27 septic arthritis patients, only 2 and 6 patients were relevant to high and intermediate probability groups and 19 were classified as a low probability group. The proportion of patients with high probability was significantly higher in patients with acute gout compared to those with septic arthritis (66.6% vs. 7.4%, p<0.001).
Conclusions This novel scoring system showed a good performance in distinguishing between acute gout and septic arthritis. It may be helpful to the primary care physicians when they have to diagnose gout without joint fluid analysis.
Janssens HJ et al. A disgnostic rule for acute gouty arthritis in primary care without joint fluid analysis Arch Intern Med. 2010;170:1120
Disclosure of Interest None Declared