Clinical score indicating the likelihood of gout
Measured Factor Detail
The Acute Gout Diagnosis Rule rules out or rules in gout diagnosis based on male sex, previous patient-reported arthritis attack, onset within 1 day, joint redness, hypertension or cardiovascular diseases, first metatarsophalangeal joint involvement, and serum uric acid levels. The score is particularly useful when the analysis of synovial fluid from the affected joint is not available. The probability of gout is high if the sum of the scores is 8 and over, undetermined if between 4 and 8, and low if below 4. For patients with scores of >4 and <8 points, analysis of synovial fluid from the affected joint for the presence of monosodium urate crystals is recommended.
Measured Factor Low Impact
- Scores ≤4 mean gout is unlikely
Measured Factor High Impact
- Scores ≥8 indicate the likelihood of gout
- Normal: Scores ≤4
- Normal Adult Male: Scores ≤4
- Normal Adult Female: Scores ≤4
- Normal Geriatric Male: Scores ≤4
- Normal Geriatric Female: Scores ≤4
The diagnostic rule was developed in a population of patients with monarthritis; therefore, it might not be applicable to patients with oligoarticular and polyarticular arthritis.
Study Validation 1
The Acute Gout Diagnosis Rule was validated in 390 patients with monoarthritis. The variables of the diagnostic rule such as male sex, previous arthritis attack, onset within 1 day, joint redness, involvement of the first metatarsophalangeal joint, cardiovascular diseases, and serum uric acid levels were determined. Data were compared with the gold standard test, which is the presence of monosodium urate crystals in joint fluid. Monosodium urate crystals were found in 219 patients (56%). The positive predictive value of a score of ≥8 points was high (0.87), the negative predictive value of a score of ≤4 points was also high (0.95). The area under the receiver operating characteristic curve for the score was 0.86 (95% CI 0.82, 0.89). Since the expected and the observed probability were in agreement, the study concluded that the Acute Gout Diagnosis Rule performed well.
Study Validation 2
This study aimed at validating gout diagnoses in 394 patients with ≥ 1 International Classification of Diseases (ICD)-10 gout diagnoses relative to five classification criteria (Rome, New York, ARA, Mexico, and Netherlands). The Netherlands criteria is also known as the Acute Gout Diagnosis rule. The presence of monosodium urate crystals in joint fluid was determined to establish gout diagnosis. Few patients met the Rome and New York cutoffs (19 % and 8 %, respectively). More patients with ≥2 gout diagnoses met the ARA, Mexico, and Netherlands cutoffs (54%, 81%, and 80%, respectively). The Mexico and Netherlands cutoffs were met more frequently by rheumatology department patients (80% and 71%, respectively). Analysis of monosodium urate crystals served to establish gout diagnoses in only 27% of rheumatology department patients. The agreement between ICD-10 gout diagnosis and the Mexico and Netherlands classification criteria was ≥80%.
Study Validation 3
This retrospective study aimed to determine whether the Acute Gout Diagnosis rule could discriminate gout from septic arthritis, which were clinically similar. The probability of gout is classified into 3 groups according to the scores: high (≥ 8), intermediate (> 4 to < 8) and low probability (≤ 4). A total of 136 patients presenting with acute monoarthritis were diagnosed as acute gout (n = 82) and septic arthritis (n = 54) based on synovial fluid analysis. The scores of acute gout patients was significantly higher than the scores of septic arthritis patients (8.6 ± 0.2 vs. 3.6 ± 0.32, P < 0.001). The probability of acute gouty arthritis, as confirmed by the presence of monosodium crystal, was 95.5% (61/64), 57.5% (19/33), and 5.1% (2/39) in high, intermediate and low probability groups, respectively. The study concluded that the Acute Gout Diagnosis rule could discriminate gout from septic arthritis.