| Key Question | Number/Type of Studies | Strength of Evidence | Findings |
|---|---|---|---|
| 1a. Diagnostic accuracy | |||
| Clinical signs and symptoms (algorithms) | 9 observational studies16, 31-34, 39-42 | Low | Tests vary in accuracy compared with synovial fluid aspiration and MSU crystal analysis. Two algorithms based on primary care patients hadsensitivities of 88% and 97%, respectively, and specificities of 75% and 96%, respectively but have undergone limited validation31, 41 |
| Dual Energy Computed Tomography (DECT) | 3 observational 1 systematic review | Low | Sensitivities ranged from 85% to 100% and specificities ranged from 83% to 92% in diagnosing gout |
| Ultrasound (US) | 4 observational 2 systematic reviews | Low | Sensitivities ranged from 37% to 100% and specificities ranged from 68% to 97%, depending on the ultrasound signs assessed; sensitivity may be lower in patients with early disease. |
| Other tests | 0 studies | Insufficient | None |
| 1b. Influence of number and types of joints involved | 0 studies | Insufficient | None |
| 1c. Influence of Symptom Duration | 0 studies | Insufficient | None |
| 1d. Influence of factors on analysis of monosodium urate crystals (MSU) | 2 observational studies 1 systematic review | Insufficient | Agreement among personnel examining synovial fluid using polarizing microscopy for detection of MSU crystals appears to be poor, but the role of training and experience are unclear. No studies examined the effect of the type of practitioner performing fluid aspiration on the ability to obtain a sample |
| 2. Adverse events and implications of misdiagnosis | 2 observational studies: 1 on AEs associated with two diagnostic methods and 1 on implications of misdiagnosis | Low | One study reported DECT and joint aspiration for MSU analysis were associated with no adverse events. |
| Implications of misdiagnosis | 1 observational study on implications of misdiagnosis | Insufficient | One study reported that missed diagnosis of gout resulted in longer hospital stays, unnecessary surgery, and delayed pharmacological treatment. |
AE = adverse event; DECT = dual-energy computed tomography; MSU = monosodium urate; US = ultrasound
From: Discussion
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