The cost-effectiveness of isotretinoin in the treatment of acne - Part 3. A cost-minimisation pharmaco-economic model

Objectives. The cost-effectiveness of systemic isotretinoin therapy in the treatment of moderate to severe acne was assessed in a comparative cost-min imisation analysis. Systemic isotretinoin at the recommended daily dose of 1 mg/kg (cumulative dose of 120 mg/kg) was compared with: (i) oral antibiot ics taken as chronic medication; (ii) a combination of chronic oral antibio tics and anti-androgen therapy; and (iii) isotretinoin prescribed only afte r two failed courses of oral antibiotics, as per South African guidelines. The perspective taken was that of the funder of health care, and the resour ces used were funder charges as a proxy for costs. Methodology. Statistical and epidemiological data as well as relevant costs from the previously reported meta-analysis and profiling study for acne th erapy were used as the clinical. basis for the construction of a cost-minim isation model. Additional costs were sourced from published pharmaceutical retail prices and professional rates. The South African treatment guideline s were used to define the frequencies associated with physician visits and pathology testing. Standard statistical methods were applied, as appropriat e. From the above, a modified Markov process was used to model the costs as sociated with the four comparator treatment regimens over a period of 120 m onths. Suitable clinical and economic endpoints were defined so that compar ison could be made between regimens. Results. Assuming a relapse rate of 21.45%, it was found that isotretinoin therapy compares favourably with the other regimens. After 50 and 35 months , systemic isotretinoin cumulative costs were less than those incurred in o ral antibiotic and oral antibiotic/anti-androgen therapy, respectively. For the stepped therapy of oral antibiotics followed by systemic isotretinoin, these break-even periods were 56 and 39 months, respectively. The cost per successfully treated patient receiving isotretinoin was R8 941. This compa res well with the cost for those patients receiving chronic oral antibiotic s, which after 5 years amounted to R10 428 per patient. Sensitivity analyse s proved these findings to be robust to variations in the isotretinoin rela pse rate, and the cost of oral antibiotic therapy and the concomitant use o f topical therapies. Conclusion. From the cost-minimisation model it is clear that where systemi c isotretinoin is clinically indicated, the sooner such therapy is initiate d the more test-effective the outcome will be. If isotretinoin is prescribe d on diagnosis of moderate to severe acne, then the cost of treatment is:si gnificantly reduced in the long term when compared with standard chronic or al antibiotic therapy.