Acute Gout Diagnosis

Acute gout diagnosis rule explained

The acute gout diagnosis criteria consists of 7 parameters which are readily available about the patient:

■ Gender – is considered because male patients carry a higher risk of developing acute gout;

■ Previously reported arthritis attack;

■ Acute onset within one day – with localization around area of feet, ankles, knees and elbows. Acute attacks most commonly reach peak within 12 - 24 hours;

■ Joint redness;

■ Metatarsophalangeal involvement – refers to the joint most involved in the gout attack, which is the big toe, also called podagra;

■ Hypertension or more than one cardiovascular disease where conditions referred to in the calculator are:

- Angina pectoris;

- Myocardial infarction;

- Transient ischemic attack;

- Cerebrovascular accident;

- Peripheral vascular disease;

■ Serum uric acid level greater than 5.88 mg/dL – one of the common positive determinations in gout, however, serum uric acid concentration cannot rule in or out the full diagnosis by itself.

This acute gout diagnosis calculator is efficient in confirming or ruling out gout and helps avoid misdiagnosis or unnecessary use of laboratory testing.

When the diagnosis is indeterminate, joint fluid aspiration for monosodium urate crystals (MSU) is required to establish diagnosis.

Result interpretation

The presence of each of the gout criteria is awarded a number of points (from 0.5 to 3.5 points), therefore, the overall score ranges from 0 to 13, where 0 is indicative of very low risk and improbable diagnosis while 13 indicates acute gout positive diagnosis is highly likely.

The final score is divided in three categories:

■ Scores between 0 and 4 carry a 2.2% prevalence of gout, therefore positive diagnosis is unlikely;

■ Scores between 4.5 and 7.5 carry a 31.2% prevalence of gout. In this case, diagnosis cannot be established for sure but neither can be ruled out. Further testing is recommended, starting with analysis of synovial fluid from an affected joint;

■ Scores between 8 and 13 carry a 80.4% prevalence of gout, therefore the positive diagnosis is highly likely. Further recommendations include initiation of corticosteroid treatment and uric acid lowering therapy.

About the study

The above diagnosis rule was created by Janssens et al. in 2010 following a study on 328 patients with monoarthritis.

Clinical variables (including tests for synovial monosodium urate crystals) were collected within 24 hours from presentation.

Their statistical significance was tested and the most appropriate have remained in the final diagnostic rule.

The positive and negative predictive values of physician gout diagnosis were 0.64 and 0.87, respectively.

The original study was validated and also tested in differential diagnosis with rheumatoid arthritis, psoriatic arthritis, pseudogout and reactive arthritis.

Gout diagnosis

The monosodium urate crystal deposition disease (gout) is characterised by the saturation in urate of the extracellular fluid.

Clinical presentation includes recurrent attacks of inflammatory arthritis, chronic arthropathy, tophaceous deposits or uric acid nephrolithiasis.

Other symptoms may include persistent joint symptoms: pain, tenderness or swelling.

The most common diagnosis method involves testing for uric acid crystals by joint fluid aspiration which basically takes liquid out of the swollen joint. The probe is analysed under polarized light.

The next step investigation is x-ray investigation to show the extent of joint damage.

The diagnosis and treatment usually takes place at primary care level, however certain cases are referred to a rheumatologist for specialized care.

Original source

Janssens HJ, Fransen J, van de Lisdonk EH, van Riel PL, van Weel C, Janssen M. A diagnostic rule for acute gouty arthritis in primary care without joint fluid analysis. Arch Intern Med. 2010; 170(13):1120-6.

Validation

Kienhorst LB, Janssens HJ, Fransen J, Janssen M. The validation of a diagnostic rule for gout without joint fluid analysis: a prospective study. Rheumatology (Oxford). 2015; 54(4):609-14.