Elsevier

Acta Tropica

Volume 91, Issue 2, July 2004, Pages 101-115
Acta Tropica

Is combination therapy for malaria based on user-fees worthwhile and equitable to consumers?: Assessment of costs and willingness to pay in Southeast Nigeria

https://doi.org/10.1016/j.actatropica.2004.03.005Get rights and content

Abstract

Objectives: To examine the equity implications of the costs of an episode of malaria, the benefit/cost ratios of using two artemisinin-based combination therapy (CT) from the consumers’ view and inequities in willingness to pay (WTP) for CT. Methods: A cross-sectional survey was conducted in Southeast Nigeria, where there is a moderate to high level of malaria resistance to chloroquine and sulfadoxine–pyrimethamine formulations. WTP was elicited from respondents using the bidding game (BG) and the structured haggling technique (SH). A socio-economic status (SES) index was used to examine the level of inequity in the key variables. In the benefit/cost ratios, the average cost of CT in Nigeria and price of CoartemR were, respectively, used as the cost inputs while the mean WTP was the measure of benefit. Multiple regression analyses were used to determine the validity of the WTP estimates. Results: More than 90% of the respondents were willing to pay for CT. The mean WTP in the BG was 301.1 Naira while it was 438.0 Naira in the SH. People in the highest SES quartile (Q4) were more willing to pay for CT than the lowest SES quartile (Q1). In the regression models, the SES quartiles were significantly related to levels of WTP. The benefit/cost ratios were higher in the SH group, and the ratio was only more than 1 using CoartemR in only the SH group. The Q1 groups had the least benefit cost-ratios but the trend of SES differentials in benefit/cost ratios were not statistically significant in the BG group but was in the SH group. Conclusion: CT based on user-fees may not be worthwhile and equitable because there are economic and equity constraints to its wide-scale use. Benefit/cost ratios depend on the type of questions that were used to elicit WTP. Governments and donors should be willing to commit funds to make CT affordable to the poor consumers for the intervention to be used to significantly reduce the burden of malaria.

Introduction

In Nigeria, falciparum malaria is the leading cause of morbidity and mortality and hence is a major contributor to the economic burden of disease in malaria holo-endemic communities (Onwujekwe et al., 2000). Treatment of cases with chloroquine (CQ) as the first line drug is a major thrust of the disease control strategy in the country. Current difficulties with the effective, safe, and affordable treatment of Plasmodium falciparum malaria world-wide is due largely to the loss of effectiveness of chloroquine, once the mainstay of control and treatment programmes, resulting from the development of drug resistant strains (Peters, 1998). The development of resistance to drugs poses one of the greatest threats to malaria control (Bloland et al., 2000).

Given the lack of affordable alternatives, chloroquine remains the first line anti-malarial agent in Nigeria and most African countries because of its low cost and availability. Studies in Nigeria have found chloroquine resistance rates of 6–64% (Umotong et al., 1991, Antia-Obong et al., 1997, Akahara and Ogbonnaya, 2001, Adagu et al., 2001), and resistance rates to sulfadoxine–pyrimethamine (SP) of up to 25% (Sowunmi and Salako, 1992, Folade et al., 1997). The drug resistance is more marked in the eastern than in the other parts of the country. Elsewhere in Africa and other parts of the world, the drug resistance rates are 31–77% to choloroquine and 3–17% to SP (Barat et al., 1998, Warsame et al., 2002). In fact chloroquine is no longer used in many parts of East and South Africa (Djimde et al., 2001).

The high levels of parasite resistance to the common mono-therapies such as CQ and common combination therapies (CTs) such as sulfadoxine–pyrimethamine have led to the evaluation and use of artemisinin-based combination therapies. These combinations have been found to be effective against drug-resistance malaria in a variety of settings (Karbwang et al., 1994, Doherty, 1999, Bloland et al., 2000, Deen et al., 2001, Olliaro, 2001, Brockman et al., 2000). However, artemisinin-based combination therapy costs substantially more than either CQ or SP (Bloland et al., 2000) and the high costs of the combination may limit their widespread use because the majority of the people that have malaria, who are predominantly poor, will not be able to afford the drugs when the first line treatments fail.

An analysis of whether people are willing to pay for CT and an assessment of the extent that the treatment is worthwhile will be useful to inform policy makers and programme managers the feasibility of using CT as first, second line or third line treatment in cases of treatment failure. It is also important to determine whether there are socio-economic differentials in economic burden of malaria, the valuation of CT and in benefit–cost computations of CT. This is because scaling-up the use of CT may be an investment decision for governments and donors, and subsidies and fee exemptions may be needed to encourage the use of CT. Even when it is proven that CT is cost-effective, but the level of utilisation of the drug is inequitable or that the people do not value the drugs enough to pay for them, treatment strategies based on such regimens may not impact much on the malaria burden in areas where they are deployed.

The usefulness of CT for adequately treating malaria cases may actually hinge on African governments vigorously investing money so as to make the drugs affordable to the end users to achieve increased productivity and record less deaths from malaria. A valuation of the costs and benefits of CT would help in making such investment decisions. A cost–benefit analysis compares the costs of the interventions with the benefits (the benefits are measured in monetary terms using the willingness to pay (WTP) technique). In benefit–cost analysis, the decision rule is that the benefit should exceed the cost for a programme to be considered worthwhile (Drummond et al., 1997).

The socio-economic differences in the willingness to pay for CT, together with their comparison with the costs of CT are examined in this paper. The assessment of equity effects of sales of CT is particularly important when note is taken of the “inverse care law” (Hart, 1971), whose logic corollary is that a new health intervention will tend to increase inequities because the intervention will initially reach those people with a higher socio-economic status (SES) than the poor—the “inverse equity hypothesis” (Victora et al., 2000).

WTP was elicited using the contingent valuation method (CVM), which is widely accepted as a theoretically correct method to estimate the value of goods and services to consumers (Brookshire et al., 1980). The CVM is based on a hypothetical market in which respondents are not actually required to make the contributions they claim to be willing to pay (Foster et al., 1997). The major criticism of the validity of CVM has been that hypothetical WTP is a poor indicator of actual WTP (Diamond and Hausmann, 1994). However, many studies have shown that CVM is a good predictor of actual WTP (Frykblom, 1997, Onwujekwe et al., 2001, Blumenschein et al., 2001, Onwujekwe, 2004).

This paper therefore presents the benefit–cost and equity implications of two artemisinin-based CT strategies that are based on user fees. It also shows how the household costs of malaria vary by socio-economic status groups, and the level of potential cost savings from using CT to treat malaria. Since “WTP is inevitably associated with ability to pay” (Donaldson et al., 1997), the examination of WTP across socio-economic and other groups could be used to ensure fairness in resource allocation, thereby maximising the societal benefits of malaria control interventions. Finally, the paper compares the theoretical validity of the estimates of WTP that were elicited using two CVM question formats.

Section snippets

Study area

Ikwo local government area of Ebonyi state, Nigeria was the study site. Ebonyi state is located in the rain-forest belt of south eastern Nigeria. The majority of the people are subsistence farmers and the main crops are cassava, rice, yam and sweet potato. Rainfall is seasonal and lasts between the months of March and October with the greatest intensity at the middle of the year. Malaria is transmitted throughout the year and the prevalence of malaria in the general population is about 46%. The

General descriptive data analysis

The demographic and other characteristics of the respondents and their households were tabulated and compared across the two question formats’ using Kruskal–Wallis χ2 tests. This was in order to see how similar the two groups were, so that differences in WTP could be attributed to the effects of the question formats. The costs and WTP estimates were expressed in the local currency, the Naira (US$ 1.00 = 125 Naira).

Descriptive characteristics of the respondents and their households

Most of the sample 285 in BG and 280 in SH responded to the interview and the rest refused to be interviewed. However, a few of the people that responded refused to answer some of the questions and their questionnaires were further dropped from the analysis. The refusals were mostly with regard to questions about WTP and food expenditures of the households. Thus, the usable numbers of questionnaires for the analysis was 228 in BG and 257 in SH.

A slight majority of the respondents were household

Discussion

At present, although combination therapy for malaria, especially combinations where artemisinin derivatives are components are effective against drug resistance malaria, cost and equity considerations may limit their use by consumers especially the most vulnerable groups in the society, usually typified by the poorest groups. It was found in this study that people bear a lot of economic burden due to malaria. It is possible that the high levels of expenditures to treat malaria could be

Conclusion

There is a need to improve the equitable use of the interventions for the control of malaria in order to reduce poverty, especially as there “is an incipient renewal of concern for poverty and equity in health” (Gwatkin, 2000). A successful solution to the inequality in access and use of interventions such as combination therapy for the control of malaria will be a major poverty reduction strategy in Nigeria. Households can spend the cost-savings from use of appropriate treatment for malaria on

Acknowledgements

This study received financial support from the UNDP/World Bank/WHO Special Programme for Research and Training in Tropical diseases. We thank Ramanan Laxinarayan for his comments during the development of the questionnaire. We also thank Nkem Dike for the comments on an earlier draft of the paper.

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