Background/Purpose: To investigate the cost-effectiveness of low-dose colchicine prophylaxis for reducing gout flares when starting allopurinol using the “start-low go-slow” approach.

Methods: This was a pre-planned secondary analysis of the “Is colchicine prophylaxis required with start-low go-slow allopurinol dose escalation in gout?” non-inferiority randomised controlled trial. In brief 200 participants with gout, fulfilling the ACR recommendations for starting urate-lowering therapy, were randomly allocated (1:1) to colchicine or placebo for the first six months, followed by a further six month follow-up. All participants received allopurinol, with monthly dose increases to achieve target urate < 6mg/dL. We assessed incremental cost-effectiveness over 6 months and 1 year, from the health system perspective, measured by incremental net monetary benefit (INMB) at a willingness-to-pay (WTP) threshold equivalent to gross domestic product per capita (GDP).

Effectiveness was measured by incremental QALYs, calculated using the EQ-5D-3L instrument and health utility values calculated using NZ population preference weights. Costs were collected using a modified version of the Otago Costs and Consequences Questionnaire (OCC-Q), which has been validated for use in economic evaluations alongside musculoskeletal clinical trials in NZ. Self-reported resource use and costs were collected at 3-, 6-, 9- and 12-month follow-up.

Results: Mean costs were higher in the colchicine group over both 6 months and 1 year (adjusted mean difference $1 860 [95%CI −273 to 3 994] and $2 304 [95%CI −142 to 4 749], respectively). QALYs slightly favoured the colchicine group over 6 months (adjusted mean difference 0.028 [95%CI −0.010 to 0.065]), but there was no difference at 12 months (−0.002, [95%CI −0.032 to 0.028]). Cost effectiveness was inconclusive at 6 months (INMB −$126 [95%CI −3 358 to 3 106], probability of cost-effectiveness 47.0%), and six months of treatment with colchicine prophylaxis was not found to be cost-effective compared to placebo at 12 months, (INMB −$2 415 [95%CI −5 611 to 781], probability of cost-effectiveness 6.5%). Similar results were obtained from a societal perspective (including non-healthcare and productivity costs). The results were robust to multiple sensitivity checks, including complete case analysis, increasing imputed costs or decreasing imputed health utility values by 10–50% to test the robustness of the estimates to deviations, and including only the per-protocol population, although at 6 months follow-up colchicine prophylaxis was cost-effective at 2x and 3x GDP WTP thresholds.

Conclusion: During the six months of treatment with colchicine prophylaxis, cost-effectiveness was inconclusive, however higher costs and QALY losses largely driven by gout flares in the six months after withdrawal of colchicine (as observed in the clinical outcomes report) indicate this regime is unlikely to be cost-effective over 1-year follow-up. Future research might focus on reduction of rebound gout flares after ceasing prophylaxis or a more prolonged period of prophylaxis when starting ULT

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/cost-effectiveness-of-low-dose-colchicine-prophylaxis-when-starting-allopurinol-using-the-start-low-go-slow-approach-for-gout/