Starting dose is a risk factor for allopurinol hypersensitivity syndrome: A proposed safe starting dose of allopurinol

Arthritis & Rheumatism, 04/16/2012

Stamp LK et al. – Starting allopurinol at a dose of 1.5mg per unit eGFR may be associated with a reduced risk of Allopurinol hypersensitivity syndrome (AHS). In patients who tolerate allopurinol the dose can be gradually increased to achieve the target SU.

Methods

  • A retrospective case–control study of patients with gout who developed AHS between January 1998 and September 2010 was undertaken.
  • For each case, three controls with gout receiving allopurinol who did not develop AHS were identified.
  • Controls were matched on gender, diuretic use at the time of commencing allopurinol, age ± 10 years, and eGFR. Analysis compared starting dose and dose at the time of the reaction between cases and controls.

Results

  • Fifty–four AHS cases and 157 controls were identified.
  • There was an increase in risk of AHS as the starting dose of allopurinol corrected for eGFR increased. For the highest quintile of starting dose≥eGFR, the odds ratio was 23.2 (p<0.01).
  • ROC analysis indicated that 91% of AHS cases and 36% of controls started on a dose of allopurinol at ≥1.5mg allopurinol per unit eGFR (mg/ml/min).

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