The current systematic review investigates the willingness to pay for HIV services in Africa. To the best of our knowledge, this is the first review on this topic. The review covers the methods used in WTP studies for HIV services in Africa and the factors associated with the willingness to pay. Twenty-two articles that met all the inclusion criteria and none of the exclusion criteria were included in the final review. The main reason for dropping some of the preference studies is that they focus on the trade-off for specific HIV services using the discrete choice and willingness to accept elicitation methods but not to assess the willingness to pay for the services.
The review includes articles that were not in three recent reviews [12, 42, 43]. The majority (72.7%) of the articles were relatively new and were published between 2016 and 2022. This coincides with the period when donor funding for HIV started to stagnate or fall and, hence, may relate to the interest in exploring alternative sources of funding [11]. All three thematic areas of HIV diagnosis, prevention and treatment were investigated using the WTP approach. Although HIV prevention had the highest number of articles amongst those included in the review, within the HIV prevention scope, there are few HIV prevention services covered by WTP studies. For instance, voluntary medical male circumcision and preexposure prophylaxis for HIV each had just one article. HIV prevention remains the hallmark for long-term control of HIV and AIDS [44], and thus, it is important that alternative measures for sustaining HIV prevention interventions in Africa be explored.
We find incomplete reporting on the methods used in WTP studies. The theories underpinning the studies and the methods used to elicit willingness to pay are two notable items that are not consistently reported in the reviewed articles. There is limited mention of the theoretical approaches to the studies on willingness to pay for HIV services in Africa. Only one study about WTP for HIV services in Nigeria explicitly states the theory underpinning the research [22], while another [40] states the conceptual framework but not the theory. Research should ideally be guided by an appropriate theory [45]. Adekunjo, Rasiah [22] used the neoclassical economic theory that assumes people to be rational and, thus, make decisions that maximise their utility [46, 47]. The neoclassical economic theory is critiqued for assuming humans are always rational; in contrast, individuals sometimes make decisions that are not in their best interests [48]. Rice [48] recommends integrating behavioural economic tools in health economics to address the shortcomings of the neoclassical theory. The available evidence indicates incomplete documentation on the method for eliciting WTP. Only fourteen out of the twenty-one quantitative studies (70%) fully mention the elicitation method for obtaining the WTP. The bidding game is the most common method used among the retrieved articles, which is similar to what other studies have found [12].
The majority (86.4%) of the included studies are conducted amongst users of the service under study. This is similar to what was found in a systematic review on WTP for HIV prevention technologies [43]. Although Foreit and Foreit [49] recommend that WTP studies for clinical services should be conducted among people attending clinics, conducting WTP studies amongst people already using the service and who already find utility in the service may lead to systematic bias [50].
Among the retrieved articles, only one uses a qualitative method, which is perhaps not surprising because WTP is largely a quantitative method. From the lone qualitative article, there is evidence of WTP for an after-hours HIV clinic. The themes in favour of WTP include perceived benefits such as privacy, less waiting time, and the convenience of attending an after-hour clinic. The themes reported from participants who were not WTP include perceived threats such as fear that payment might become mandatory, including the general clinic, poor quality services for those in the general clinic who are unable to pay for the after-hours clinic, and the belief that HIV services should be free. The qualitative findings highlight the importance of exploring other factors beyond the ability to pay that influence willingness to pay. The key informants who were high net worth individuals and, thus, more likely to be able to pay are concerned not only about the quality of care in the after-hours clinic but also in the general clinic where those who are unable to pay seek care. The qualitative findings are similar to what Steigenberger, Flatscher-Thoeni [12] found that perceived benefits and fears/threats are among the factors that influence WTP for health services.
Almost all the studies (90.9%) used interview-administered questionnaires to collect data, with only two studies reporting the use of self-administered questionnaires [27, 28]. Interactive data collection formats that allow clarification of questions and probing for higher amounts are generally recommended for WTP [51, 52].
The review finds evidence of willingness to pay for HIV services even though the amount is not sufficient to pay for the full service at market value. The proportion of people willing to pay ranged from 34.3–97.1%. A greater proportion are more willing to pay for HIV diagnosis compared to prevention and treatment. This may be attributed to the fact that HIV diagnosis costs much less compared to HIV prevention and treatment service, and thus, many more people are able to afford it. Several factors are significantly associated with the willingness to pay for HIV services. Among the factors, income (including ability to pay, employment, and socioeconomic status) was the most frequently mentioned, followed by knowledge and beliefs about the HIV service or product. Other factors include level of education, being male and the influence of other people. These factors are similar to what has been previously reported [12, 53, 54].
The review has several strengths compared to other recent reviews. We attempted to address the limitation of excluding qualitative articles from preference elicitation studies, as acknowledged in the systematic review by Beckham, Crossnohere [35]. Our search for evidence included grey literature sources that were omitted by other reviews [42, 43]. All the studies included were classified as medium to high quality. However, our review is not without limitations. Willingness to pay is largely a quantitative approach. Although we tried to include qualitative articles, there is a possibility that our search criteria may not have been sensitive enough, and thus, we may have missed some articles that used qualitative methods. We restricted our search to only articles in English, which also may have excluded important articles in other languages. One of the limitations of contingent valuation studies is the assumption that stated preference equates to actual payment, which may not be the case, and this systematic review is no exception; thus, the findings should be interpreted with some caution.