Price MA, Stewart SR, Miller WC, Behets F, Dow WH, Martinson FE, Chilongozi D, Cohen MS. The Cost-Effectiveness of Treating Male Trichomoniasis to Avert HIV Transmission in Men Seeking Sexually Transmitted Disease Care in Malawi. J Acquir Immune Defic Syndr. 2006 Oct 1;43(2):202-9.
To examine the cost-effectiveness of providing first-line treatment for male trichomoniasis to avert new HIV infections in Malawi.
This was a cost-effectiveness modeling study using a standard decision tree analysis applied to a population of 10,000 semi-urban men seeking STD treatment over a one year period. Currently in Malawi, only men who are partners of women with trichomoniasis receive metronidazole. This model estimated the cost of treatment and the number of HIV infections averted due to treatment of Trichomonas vaginalis (TV), comparing three different treatment strategies: (1) treating men with urethritis; (2) treating men who have either urethritis or genital ulcer disease (GUD); (3) universally treating all male attendees of the STD clinic.
The model was based on primary data available from a study based at the STD clinic in the Lilongwe Central Hospital, a government hospital in Malawi. The study, conducted from January 2000 through January 2001, enrolled males with GUD and urethritis; men were randomized to treatment with 2g of metronidazole or placebo. Parameter values for the model were taken from study findings, as well as Ministry of Health data and other published work.
Data on participants in the model were based on males with GUD or urethritis attending the STD clinic in Lilongwe, Malawi. Prevalence of trichomoniasis in this population was 20%, and the HIV prevalence was 44%.
The incremental cost-effectiveness of three treatment regimens for trichomoniasis was compared to the status quo treatment regimen at the STD clinic in Malawi.
Incremental cost-effectiveness ratios (ICER) and total program costs were the primary outcomes. Sensitivity analyses were also performed. ICER were calculated by dividing the incremental costs incurred by each program by the number of HIV cases averted, relative to the treatment status quo.
Base-case Analysis: The authors estimated the risks for transmission and acquisition of HIV attributable to trichomoniasis at 0.0314 and 0.0161, respectively. Assuming a 10% TV re-infection rate, and that one-third of men seek appropriate treatment in a timely manner, persistent male trichomoniasis is responsible for 27.2 new cases of HIV per 10,000 men. Under the three alternative treatment strategies: 1) men with urethritis, 2) men with urethritis or GUD, and 3) all men, the number of new HIV cases would decrease to 18.6, 7.3, and 4.5, respectively. The corresponding incremental cost-effectiveness ratios would be $32.27 additional per HIV case averted, $15.85, and $15.43, respectively.
Sensitivity Analysis: Results of the model were most sensitive to variations in HIV transmission rates, and somewhat sensitive to variations in prevalence of T. vaginalis, re-infection rates, and cost of return visits. The best-case and worst-case scenarios (based on varying prevalence, transmission, re-infection rates, and partner treatment) resulted in a range in the number of HIV infections averted of: strategy 1: 2.4-14.3 HIV infections averted; strategy 2: 4.8-28.5 HIV infections averted; and strategy 3: 5.7-33.8 HIV infections averted.
The authors conclude that universally treating males for T. vaginalis when they present to an STD clinic could be a cost-effective means to avert HIV infections. Between six and 52 new HIV infections could be prevented per 10,000 clinic attendees, at a cost ranging from $2 to $62 per infection averted.
The Quality of Health Economic Studies (QHES) instrument was used to assess the quality of this study.(1) The instrument uses 16 criteria based on methods and reporting of results, each assigned a weighted point value, for a total of 100 points. This study scored 100 out of 100. Limitations pointed out by the authors include the difficulty in estimating the attributable risk of HIV infection to T. vaginalis infection, particularly as the model was most sensitive to variations in this parameter. The authors therefore suggest that the ICERs should be interpreted as ranges based on the sensitivity analysis, rather than as point estimates. Even at the lowest value for attributable risk, the treatment for trichomoniasis still remains highly cost-effective.
Cost-effectiveness of other interventions in the developing world aimed at averting new cases of HIV have been studied, and the results of this study compare favorably with blood screening, VCT, and PMTCT programs.(2) Cost of infections averted by other STD programs in Tanzania and Kenya have been estimated at $150-260 per case averted.(3,4)
The authors state that because metronidazole is already in use in Malawi for treatment of symptomatic women and their asymptomatic partners, logistical challenges to expanding treatment to all men would be minimal, and universal treatment of males in a clinic where the prevalence is 20% adds up to only $0.25 per case treated. With new evidence that trichomoniasis is associated with increased risk of HIV transmission, treatment of this often neglected STD could be cheap and effective. As the prevalence of trichomoniasis can vary widely throughout the world, however, other programs should first determine whether TV is prevalent in their population at risk.
Ofman JJ, Sullivan SD, Neumann PJ, Chiou CF, Henning JM, Wade SW, Hay JW. Examining the value and quality of health economic analyses: implications of utilizing the QHES. J Manag Care Pharm. 2003 Jan-Feb;9(1):53-61.
Walker D. Cost and cost-effectiveness of HIV/AIDS prevention strategies in developing countries: is there an evidence base? Health Policy Plan. 2003 Mar;18(1):4-17.
Gilson L, Mkanje R, Grosskurth H, Mosha F, Picard J, Gavyole A, Todd J, Mayaud P, Swai R, Fransen L, Mabey D, Mills A, Hayes R. Cost-effectiveness of improved treatment services for sexually transmitted diseases in preventing HIV-1 infection in Mwanza Region, Tanzania. Lancet. 1997 Dec 20-27;350(9094):1805-9.
Moses S, Plummer FA, Ngugi EN, Nagelkerke NJ, Anzala AO, Ndinya-Achola JO. Controlling HIV in Africa: effectiveness and cost of an intervention in a high-frequency STD transmitter core group. AIDS. 1991 Apr;5(4):407-11.