Acute Gout Diagnosis Calculator

How does this acute gout diagnosis calculator work?

This health tool is used in the diagnosis of acute gout and consists of 7 parameters considered as risk factors of gout and aims to avoid misdiagnosis or unnecessary use of laboratory testing:

■ Gender – male patients have a higher risk of developing acute gout;

■ Previously reported arthritis attack;

■ Acute onset within 1 day – acute gout attacks with the most frequent areas that of feet, ankles, knees and elbows. Acute attacks usually reach peak within 12 - 24 hours;

■ Joint redness;

■ Metatarsophalangeal involvement – this is the joint most involved in gout, the big toe, also called podagra;

■ Hypertension or more than 1 cardiovascular disease;

■ Serum uric acid level greater than 5.88 mg/dL – while serum uric acid concentrations can be supportive of diagnosis, their elevation alone cannot rule in or out the full diagnosis.

The cardiovascular diseases referred to in the score are:

■ Angina pectoris;

■ Myocardial infarction;

■ Cerebrovascular accident;

■ Transient ischemic attack;

■ Peripheral vascular disease.

This acute gout diagnosis calculator is most useful in determining which patients are high risk and which are in indeterminate cases and might need joint fluid aspiration for monosodium urate crystals (MSU), thus reducing the use of these time and money consuming investigations.

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

Gout score interpretation

Each of the 7 variables has 2 answer choices, usually confirming or infirming the hypothesis in question, one awarded 0 points and the other awarded from 0.5 to 3.5 points, depending on the weight given to each parameter.

Therefore the overall score ranges from 0 to 13, where 0 is indicative of very low risk and improbable diagnosis and 13 indicates very high risk of acute gout.

The three score categories are as follows:

■ 0 - 4: 2.2% prevalence of gout – Improbable diagnosis;

■ 4.5 - 7.5: 31.2% prevalence of gout – Diagnosis cannot be established but cannot be ruled out either. Further testing for monosodium urate crystals, starting with analysis of synovial fluid from one affected joint is recommended;

■ 8 - 13: 80.4% prevalence of gout – Diagnosis positive – recommended to start treatment with corticosteroids, uric acid lowering therapy and be evaluated for gout associated diseases.

Gout diagnosis methods

Gout, also known as monosodium urate crystal deposition disease consists of the saturation in urate of the extracellular fluid. Clinical presentation includes recurrent attacks of inflammatory arthritis, the existence of a chronic arthropathy, tophaceous deposits or uric acid nephrolithiasis.

The diagnosis is usually put at the presence of uric acid crystals by joint fluid aspiration which drags liquid out of the swollen joint. The probe is then analyzed under polarized light.

Acute attacks are often characterized by the existence of intracellular crystals with a neutrophil.

The next step and the recommendation in case the patient presents with persistent joint symptoms: pain, tenderness, swelling or tophi areas under the skin, is x-ray investigation to show the extent of joint damage.

Primary care doctors are usually the ones in charge with diagnosis and treatment of gout, however certain cases might be referred to a rheumatologist for special care.

References

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

2) Dalbeth N, Fransen J, Jansen TL et al. (2013) New classification criteria for gout: a framework for progress. Rheumatology (Oxford); 52(10): 1748–1753.

3) Kienhorst LB, Janssens HJ, Fransen J, Janssen M. (2015) Comment on: The validation of a diagnostic rule for gout without joint fluid analysis: a prospective study: reply. Rheumatology (Oxford); 54(7):1329-30.