Preventing Mycobacterium avium complex in patients who are using protease inhibitors: a cost-effectiveness analysis.
BACKGROUND
Practice guidelines recommending Mycobacterium avium complex (MAC) prophylaxis for patients with HIV disease were based on clinical trials in which individuals did not receive protease inhibitors.


OBJECTIVE
To estimate the cost-effectiveness of strategies for MAC prophylaxis in patients whose treatment regimen includes protease inhibitors.


METHODS
Decision analysis with Markov modelling of the natural history of advanced HIV disease. Five strategies were evaluated: no prophylaxis, azithromycin, rifabutin, clarithromycin and a combination of azithromycin plus rifabutin.


METHODS
Survival, quality of life, quality-adjusted survival, health care costs and marginal cost-effectiveness ratios.


RESULTS
Compared with no prophylaxis, rifabutin increased life expectancy from 78 to 80 months, increased quality-adjusted life expectancy from 50 to 52 quality-adjusted months and increased health care costs from $233000 to $239800. Ignoring time discounting and quality of life, the cost-effectiveness of rifabutin relative to no prophylaxis was $44300 per life year. Adjusting for time discounting and quality of life, the cost-effectiveness of rifabutin relative to no prophylaxis was $41500 per quality-adjusted life year (QALY). In comparison with rifabutin, azithromycin was associated with increased survival, increased costs and an incremental cost-effectiveness ratio of $54300 per QALY. In sensitivity analyses, prophylaxis remained economically attractive unless the lifetime chance of being diagnosed with MAC was less than 20%, the rate of CD4 count decline was less than 10 x 10(6) cells/l per year, or the CD4 count was greater than 50 x 10(6) cells/l.


CONCLUSIONS
MAC prophylaxis increases quality-adjusted survival at a reasonable cost, even in patients using protease inhibitors. When not contraindicated, starting azithromycin or rifabutin when the patient's CD4 count is between 50 and 75 x 10(6) cells/l is the most cost-effective strategy. The main determinants of cost-effectiveness are CD4 count, viral load, place of residence and patient preference.
Bayoumi
A M
AM
Department of Medicine, University of Toronto, Canada.
Redelmeier
D A
DA
D017088:AIDS-Related Opportunistic Infections / Q000191:economics / Q000401:mortality / Q000517:prevention & control*; D000328:Adult; D000900:Anti-Bacterial Agents; D019072:Antibiotic Prophylaxis / Q000191:economics*; D000904:Antibiotics, Antitubercular; D017963:Azithromycin; D017291:Clarithromycin; D003362:Cost-Benefit Analysis; D004359:Drug Therapy, Combination; D015658:HIV Infections / Q000188:drug therapy* / Q000401:mortality; D017320:HIV Protease Inhibitors / Q000627:therapeutic use*; D017048:Health Care Costs; D006801:Humans; D008297:Male; D008390:Markov Chains; D015269:Mycobacterium avium Complex; D015270:Mycobacterium avium-intracellulare Infection / Q000191:economics / Q000401:mortality / Q000517:prevention & control*; D011788:Quality of Life; D017828:Rifabutin; D014481:United States
D000900:Anti-Bacterial Agents; D000904:Antibiotics, Antitubercular; D017320:HIV Protease Inhibitors; D017828:Rifabutin; D017963:Azithromycin; D017291:Clarithromycin