Hypothetical and actual willingness to pay for insecticide-treated nets in five Nigerian communities

Parents' willingness to pay for children's spectacles in Cambodia

Background/aim

To determine willingness to pay for children's spectacles, and barriers to purchasing children's spectacles in Cambodia.

Methods

We conducted vision screenings, and eye examinations as indicated, for all consenting children at 21 randomly selected secondary schools. We invited parents/guardians of children found to have refractive problems to complete a willingness to pay for spectacles survey, using a binary-with-follow-up technique.

Results

We conducted vision screenings on 12 128 secondary schoolchildren, and willingness to pay for spectacles surveys with 491 parents/guardians (n=491) from Kandal and Phnom Penh provinces in Cambodia. We found 519 children with refractive error, 7 who had pre-existing spectacles and 14 recommended spectacles for lower ametropias. About half (53.2%; 95% CI 44.0% to 62.1%) of parents/guardians were willing to pay KHR70 000 (US$17.5; average market price) or more for spectacles. Mean willingness-to-pay price was KHR74 595 (US$18.6; 95% CI KHR64 505 to 86 262; 95% CI US$16.1 to US$21.6) in Phnom Penh and KHR55 651 (US$13.9; 95% CI KHR48 021 to 64 494; 95% CI US$12.0 to US$16.1) in Kandal province. Logistic regression suggested parents/guardians with college education (OR 6.8; p<0.001), higher household incomes (OR 8.0; p=0.006) and those wearing spectacles (OR 2.2; p=0.01) were more likely to be willing to pay ≥US$17.5. The most common reasons for being unwilling to pay US$17.5 were related to cost (58.8%). The most common barrier to spectacle wear was fear that spectacles weaken children's eyes (36.0%).

Conclusions

With almost half of parents/guardians unwilling to pay for spectacles at the current average market price, financial support through a subsidised spectacle scheme might be required for children to access spectacles in Cambodia.

The criterion validity of willingness to pay methods: A systematic review and meta-analysis of the evidence

BACKGROUND

The contingent valuation (CV) method is used to estimate the willingness to pay (WTP) for services and products to inform cost benefit analyses (CBA). A long-standing criticism that stated WTP estimates may be poor indicators of actual WTP, calls into question their validity and the use of such estimates for welfare evaluation, especially in the health sector. Available evidence on the validity of CV studies so far is inconclusive. We systematically reviewed the literature to (1) synthesize the evidence on the criterion validity of WTP/willingness to accept (WTA), (2) undertake a meta-analysis, pooling evidence on the extent of variation between stated and actual WTP values and, (3) explore the reasons for the variation.

METHODS

Eight electronic databases were searched, along with citations and reference reviews. 50 papers detailing 159 comparisons were identified and reviewed using a standard proforma. Two reviewers each were involved in the paper selection, review and data extraction. Meta-analysis was conducted using random effects models for ratios of means and percentage differences separately. Meta-bias was investigated using funnel plots.

RESULTS

Hypothetical WTP was on average 3.2 times greater than actual WTP, with a range of 0.7-11.8 and 5.7 (0.0-13.6) for ratios of means and percentage differences respectively. However, key methodological differences between surveys of hypothetical and actual values were found. In the meta-analysis, high levels of heterogeneity existed. The overall effect size for mean summaries was 1.79 (1.56-2.04) and 2.37 (1.93-2.80) for percent summaries. Regression analyses identified mixed results on the influence of the different experimental protocols on the variation between stated and actual WTP values. Results indicating publication bias did not account for differences in study design.

CONCLUSIONS

The evidence on the criterion validity for CV studies is more mixed than authors are representing because substantial differences in study design between hypothetical and actual WTP/WTA surveys are not accounted for.

Willingness to pay for antiretroviral drugs among HIV and AIDS clients in south-east Nigeria

BACKGROUND

The current trend of withdrawal of donor support for HIV/AIDS treatment in Nigeria may require that the cost of antiretroviral drugs be borne in part by infected people and their families.

OBJECTIVE

This study was conducted to determine the economic value for free antiretroviral drugs (ARVs) expressed by clients receiving treatment for HIV/AIDS in a tertiary hospital.

STUDY METHOD

The contingent valuation method was used to elicit the values attached to free ARVs from people living with HIV/AIDS that were receiving care in a public tertiary hospital in south-east Nigeria. Exit poll using a pre-tested questionnaire was undertaken with adult clients on treatment. The bidding game technique was used to elicit their willingness to pay (WTP) for ARVs for themselves and members of their households. Ordinary least squares (OLS) multiple regression analysis was used to test the construct validity of elicited WTP amounts.

RESULTS

About a third of the respondents were willing to pay for a monthly supply of ARVs for themselves and household members. The mean WTP for monthly supply of ARVs for self was US$15.32 and for household member was US$15.26 (1US$=₦160). OLS regression analysis showed that employment status and higher socio-economic status were positively associated with higher WTP. OLS showed that age and transport cost per clinic visit were negatively related to WTP. Knowing the risks of not adhering to treatment protocol was positively related to WTP.

CONCLUSION

The respondents positively valued the free ARVs. This calls for greater financial support for the sustainable provision of the treatment service. However, holistic financing mechanisms should be explored to ensure sustained funding in the event of complete withdrawal of donor support.

Economic and social factors that influence households not willing to undergo cataract surgery

Purpose:

Literature investigating barriers to cataract surgery is mostly done from the patient's point of view. However, many medical decisions are jointly taken by household members, especially in developing countries such as India. We investigated from the household head's (or representative's) perspective, households’ view on those not willing to undergo cataract surgery along with the economic and social factors associated with it.

Materials and Methods:

A cross-sectional survey of four randomly selected village clusters in rural areas of Theni district, Tamil Nadu, India, was conducted to elicit the willingness to pay for cataract surgery by presenting “scenarios” that included having or not having free surgery available. The presentation of scenarios allowed the identification of respondents who were unwilling to undergo surgery. Logistic regression was used to estimate relationships between economic and social factors and unwillingness to undergo cataract surgery.

Results:

Of the 1271 respondents, 49 (3.85%) were not willing to undergo surgery if they or their family members have cataract even if free surgery were available. In the regression results, those with good understanding of cataract and its treatment were less likely to be unwilling to undergo cataract surgery. Those not reporting household income were more likely to be unwilling to undergo cataract surgery.

Conclusions:

As a good understanding of cataract was an important predictor of willingness to undergo cataract surgery, health education on cataract and its intervention can improve uptake.

Malaria prevalence, anemia and baseline intervention coverage prior to mass net distributions in Abia and Plateau States, Nigeria

Background

Nigeria suffers the world’s largest malaria burden, with approximately 51 million cases and 207,000 deaths annually. As part of the country’s aim to reduce by 50% malaria-related morbidity and mortality by 2013, it embarked on mass distribution of free long-lasting insecticidal nets (LLINs).

Methods

Prior to net distribution campaigns in Abia and Plateau States, Nigeria, a modified malaria indicator survey was conducted in September 2010 to determine baseline state-level estimates of Plasmodium prevalence, childhood anemia, indoor residual spraying (IRS) coverage and bednet ownership and utilization.

Results

Overall age-adjusted prevalence of Plasmodium infection by microscopy was similar between Abia (36.1%, 95% CI: 32.3%–40.1%; n = 2,936) and Plateau (36.6%, 95% CI: 31.3%–42.3%; n = 4,209), with prevalence highest among children 5-9 years. P. malariae accounted for 32.0% of infections in Abia, but only 1.4% of infections in Plateau. More than half of children ≤10 years were anemic, with anemia significantly higher in Abia (76.9%, 95% CI: 72.1%–81.0%) versus Plateau (57.1%, 95% CI: 50.6%–63.4%). Less than 1% of households in Abia (n = 1,305) or Plateau (n = 1,335) received IRS in the 12 months prior to survey. Household ownership of at least one bednet of any type was 10.1% (95% CI: 7.5%–13.4%) in Abia and 35.1% (95% CI: 29.2%-41.5%) in Plateau. Ownership of two or more bednets was 2.1% (95% CI: 1.2%–3.7%) in Abia and 14.5% (95% CI: 10.2%–20.3%) in Plateau. Overall reported net use the night before the survey among all individuals, children <5 years, and pregnant women was 3.4%, 6.0% and 5.7%, respectively in Abia and 14.7%, 19.1% and 21.0%, respectively in Plateau. Among households owning nets, 34.4% of children <5 years and 31.6% of pregnant women in Abia used a net, compared to 52.6% of children and 62.7% of pregnant women in Plateau.

Conclusions

These results reveal high Plasmodium prevalence and childhood anemia in both states, low baseline coverage of IRS and LLINs, and sub-optimal net use—especially among age groups with highest observed malaria burden.

Household preferences for cataract surgery in rural India: a population-based stated preference survey

PURPOSE

Cataract surgery is provided both by the private and public sector in India. Free cataract surgery (with minimal amenities) funded through subsidies/reimbursements by government and non-governmental organizations is provided for underprivileged and poor patients, especially in rural areas. However, no evidence exists whether this free surgery is used by those who could afford to pay and are willing to pay for cataract surgery. So, understanding willingness to pay and preferences for cataract surgery in the population can have important policy implications.

METHODS

A cross-sectional survey of 1272 households from four randomly drawn rural household clusters in Theni district, Tamilnadu state, India was conducted. Respondents from households were presented with scenarios (with and without free surgery availability) to elicit their willingness to pay and preferences for cataract surgery.

RESULTS

Of those willing to undergo surgery; 696 (57%) were willing to undergo paid surgery, 148 (12%) only free surgery, and 378 (31%) paid surgery if no free surgery was available. In a multinomial logit model, household wealth measures, income variables and family history of cataract surgery largely distinguished the preferences. Good understanding of cataract and its intervention only marginally influenced preference for paid surgery.

CONCLUSION

A larger number of people were willing to pay when free surgery was not available. Free surgery may be crowding out surgery for which costs can be recovered. With non-cataract causes of blindness in the Indian population also requiring attention, this has implications for allocation of scarce resources.

A systematic review and meta-analysis of willingness-to-pay values: the case of malaria control interventions

The increasing use of willingness to pay (WTP) to value the benefits of malaria control interventions offers a unique opportunity to explore the possibility of estimating a transferable indicator of mean WTP as well as studying differences across studies. As regression estimates from individual WTP studies are often assumed to transfer across populations it also provides an opportunity to question this practice. Using a qualitative review and meta analytic methods, this article determines what has been studied and how, provides a summary mean WTP by type of intervention, considers how and why WTP estimates vary and advises on future reporting of WTP studies. WTP has been elicited mostly for insecticide-treated nets, followed by drugs for treatment. Mean WTP, including zeros, is US$2.79 for insecticide-treated nets, US$6.65 for treatment and US$2.60 for other preventive services. Controlling for a limited number of sample and design effects, results can be transferred to different countries using the value function. The main concerns are the need to account for a broader range of explanators that are study specific and the ability to transfer results into malaria contexts beyond those represented by the data. Future studies need to improve the reporting of WTP.

Willingness-to-pay for a rapid malaria diagnostic test and artemisinin-based combination therapy from private drug shops in Mukono District, Uganda

In Uganda, as in many parts of Africa, the majority of the population seek treatment for malaria in drug shops as their first point of care; however, parasitological diagnosis is not usually offered in these outlets. Rapid diagnostic tests (RDTs) for malaria have attracted interest in recent years as a tool to improve malaria diagnosis, since they have proved accurate and easy to perform with minimal training. Although RDTs could feasibly be performed by drug shop vendors, it is not known how much customers would be willing to pay for an RDT if offered in these settings. We conducted a contingent valuation survey among drug shop customers in Mukono District, Uganda. Exit interviews were undertaken with customers aged 15 years and above after leaving a drug shop having purchased an antimalarial and/or paracetamol. The bidding game technique was used to elicit the willingness-to-pay (WTP) for an RDT and a course of artemisinin-based combination therapy (ACT) with and without RDT confirmation. Factors associated with WTP were investigated using linear regression. The geometric mean WTP for an RDT was US$0.53, US$1.82 for a course of ACT and US$2.05 for a course of ACT after a positive RDT. Factors strongly associated with a higher WTP for these commodities included having a higher socio-economic status, no fever/malaria in the household in the past 2 weeks and if a malaria diagnosis had been obtained from a qualified health worker prior to visiting the drug shop. The findings further suggest that the WTP for an RDT and a course of ACT among drug shop customers is considerably lower than prevailing and estimated end-user prices for these commodities. Increasing the uptake of ACTs in drug shops and restricting the sale of ACTs to parasitologically confirmed malaria will therefore require additional measures.

Formative research for the development of a market-based home fortification programme for young children in Niger

The objective of this formative research was to assess the acceptability of a micronutrient powder (Sprinkles(®)) and a lipid-based nutrient supplement (Nutributter(®)), and to explore people's willingness to pay for these products in a resource-poor context like Niger. In four sites, 84 focus group discussions among mothers, fathers and grandmothers of children 6-23 months were conducted, as well as 80 key informant interviews of mothers who participated in a home study where their children 6-23 months were given either Sprinkles(®) or Nutributter(®) to use either for a period of 4 weeks, or they were given both products over the 4-week period, i.e. Sprinkles(®) for 2 weeks and Nutributter(®) for an additional 2 weeks. The mothers understood how to use the products and generally used the products correctly. Both products were highly acceptable to adults and most children. In Niamey, where the 4-week home study used both products for 2 weeks each, the mothers tended to prefer Nutributter(®). The mothers who used either product were pleased with the improvements they saw in their children's health, including increased appetite, weight gain and increased energy and activity. A few mothers were concerned with how they would be able to provide for their child's increased appetite. Most participants across all four sites reported that they would be willing and able to afford to buy a single sachet of either Sprinkles(®) at a cost of US$0.03 or Nutributter(®) at a cost of US$0.08 several times a week. This study provides evidence that both of these products were are highly acceptable in different settings in Niger and suggests that delivery of Nutributter(®) or Sprinkles(®) at a low or subsidized cost through a market-based system may be possible in Niger, if an appropriate distribution system can be identified.

Risk communication in clinical trials: a cognitive experiment and a survey

BACKGROUND

A Royal Statistical Society Working Party recently recommended that "Greater use should be made of numerical, as opposed to verbal, descriptions of risk" in first-in-man clinical trials. This echoed the view of many clinicians and psychologists about risk communication. As the clinical trial industry expands rapidly across the globe, it is important to understand risk communication in Asian countries.

METHODS

We conducted a cognitive experiment about participation in a hypothetical clinical trial of a pain relief medication and a survey in cancer and arthritis patients in Singapore. In part 1 of the experiment, the patients received information about the risk of side effects in one of three formats (frequency, percentage and verbal descriptor) and in one of two sequences (from least to most severe and from most to least severe), and were asked about their willingness to participate. In part 2, the patients received information about the risk in all three formats, in the same sequence, and were again asked about their willingness to participate. A survey of preference for risk presentation methods and usage of verbal descriptors immediately followed.

RESULTS

Willingness to participate and the likelihood of changing one's decision were not affected by the risk presentation methods. Most patients indicated a preference for the frequency format, but patients with primary school or no formal education were indifferent. While the patients used the verbal descriptors "very common", "common" and "very rare" in ways similar to the European Commission's Guidelines, their usage of the descriptors "uncommon" and "rare" was substantially different from the EU's.

CONCLUSION

In this sample of Asian cancer and arthritis patients, risk presentation format had no impact on willingness to participate in a clinical trial. However, there is a clear preference for the frequency format. The lay use of verbal descriptors was substantially different from the EU's.

The effect of protest zeros on estimates of willingness to pay in healthcare contingent valuation analysis

'Protest zeros' occur when respondents reject some aspect of the contingent valuation (CV) market scenario by reporting a zero value even though they place a positive value on the amenity being valued. This is inevitable even in the best-designed CV study, and, when excluded on an ad hoc basis, may cause a selection bias problem. This could affect the reliability of the willingness to pay (WTP) estimates obtained for preference assessment. Treatment of 'protest zeros' in general, and particularly in the context of developing countries, has been rather unsatisfactory. Most case studies employ the Heckman 2-step approach, which is much less robust to co-linearity problems than the Full Information Maximum Likelihood (FIML) estimator. The main objective of this article is to illustrate a sequential procedure to simultaneously deal with co-linearity and selectivity bias resulting from excluding 'protest zeros' in CV analysis. The sequential procedure involves different levels of estimation and diagnostics with the 2-step and FIML estimators; the duration of the procedure depends on the diagnostic test results at each stage of the estimations. The data used for the analysis were elicited using the conventional dichotomous choice buttressed with an open-ended follow-up question. The survey was designed to elicit households' WTP for a proposed community-based malaria control scheme in rural Cameroon. In the application context, we found that the different levels of estimation and diagnostics resulted in reliable WTP estimates from the FIML approach, which would obviously have been overlooked in the absence of such diagnostics.

The state of health economic evaluation research in Nigeria: a systematic review

This study assessed the state of health economic evaluation (including pharmacoeconomic) research in Nigeria. A literature search was conducted to identify health economic articles pertaining to Nigeria. Two reviewers independently scored each article in the final sample using a data collection form designed for the study. A total of 44 studies investigating a wide variety of diseases were included in the review. These articles were published in 34 different journals, mostly based outside of Nigeria, between 1988 and 2009. On average, each article was written by four authors. Most first authors had medical/clinical affiliations and resided in Nigeria at the time of publication of the study. Based on a 1 to 10 scale, with 10 indicating the highest quality, the mean quality score for all studies was 7.29 (SD 1.21) and 59% of the articles were of fair quality (score 5-7); 5% were of even lower quality. The quality of articles was statistically significantly (p < or = 0.05) related to the country of residence of the primary author (non-Nigeria = higher), country of the journal (non-Nigeria = higher), primary objective of the study (economic analysis = higher) and type of economic analysis conducted (economic evaluations higher than cost studies). The conduct of health economic (including pharmacoeconomic) research in Nigeria was limited and about two-thirds of published articles were of sub-optimal quality. More and better quality health economic research in Nigeria is warranted.

"If you have the flu symptoms, your asymptomatic spouse may better answer the willingness-to-pay question". Evidence from a double-bounded dichotomous choice model with heterogeneous anchoring

The small sample size of contingent valuation (CV) surveys conducted in patients may have limited the use of the single-bounded (SB) dichotomous choice format which is recommended in environmental economics. In this paper, we explore two ways to increase the statistical efficiency of the SB format: (1) by the inclusion of proxies in addition to patients; (2) by the addition of a follow-up dichotomous question, i.e. the double-bounded (DB) dichotomous choice format. We found that patients (n=223) and spouses (n=64) answering on behalf of the patient had on average a similar willingness-to-pay for earlier alleviation of flu symptoms. However, a patient was significantly more likely to anchor his/her answer on the first bid as compared to a spouse. Finally, our original DB model with shift effect and heterogeneous anchoring reconciled the discrepancies found in willingness-to-pay statistics between SB and DB models in keeping with increased statistical efficiency.

Determinants of household demand for bed nets in a rural area of southern Mozambique

Background

A key to making insecticide-treated nets (ITNs) a long-term, sustainable solution to the spread of malaria is understanding what drives their purchase and use. Few studies have analysed the determinants of demand for bed nets for malaria prevention at the household level, and in particular, how demand for nets compares with demand for other mosquito prevention methods.

Methods

This study uses a household survey to assess the determinants of demand for bed nets in an area of endemic malaria transmission in rural, southern Mozambique. The study looks at willingness to pay (WTP) for bed nets, net ownership, usage, and past purchase behaviour, alongside expenditure and frequency of use of alternate methods for malaria prevention.

Results

While overall net ownership in the sample is low, the evidence fails to suggest that poorer households are less likely to own bed nets, when controlling for covariates, nor does the likelihood of receiving a free net depend on socioeconomic status (SES). Formal schooling and market knowledge seem to indicate higher average willingness to pay, while use of alternate methods for malaria prevention, and receipt of Indoor Residual Spraying (IRS) are found to decrease demand for bed nets.

Conclusion

For long-term sustainability of ITNs to be realized, results suggest that either full or partial subsidies may be necessary in some contexts to encourage households to obtain and use nets. Given the possible substitution effects of combined malaria control interventions, and the danger of not taking into consideration household preferences for malaria prevention, successful malaria control campaigns should invest a portion of their funds towards educating recipients of IRS and users of other preventive methods on the importance of net use even in the absence of mosquitoes.

Bed net use and associated factors in a rice farming community in Central Kenya

Background

Use of insecticide-treated nets (ITNs) continues to offer potential strategy for malaria prevention in endemic areas. However their effectiveness, sustainability and massive scale up remain a factor of socio-economic and cultural variables of the local community which are indispensable during design and implementation stages.

Methods

An ethnographic household survey was conducted in four study villages which were purposefully selected to represent socio-economic and geographical diversity. In total, 400 households were randomly selected from the four study villages. Quantitative and qualitative information of the respondents were collected by use of semi-structured questionnaires and focus group discussions.

Results

Malaria was reported the most frequently occurring disease in the area (93%) and its aetiology was attributed to other non-biomedical causes like stagnant water (16%), and long rains (13%). Factors which significantly caused variation in bed net use were occupant relationship to household head (χ² = 105.705; df 14; P = 0.000), Age (χ² = 74.483; df 14; P = 0.000), village (χ² = 150.325; df 6; P = 0.000), occupation (χ² = 7.955; df 3; P = 0.047), gender (χ² = 4.254; df 1; P = 0.039) and education levels of the household head or spouse (χ² = 33.622; df 6; P = 0.000). The same variables determined access and conditions of bed nets at household level. Protection against mosquito bite (95%) was the main reason cited for using bed nets in most households while protection against malaria came second (54%). Colour, shape and affordability were some of the key potential factors which determined choice, use and acceptance of bed nets in the study area.

Conclusion

The study highlights potential social and economic variables important for effective and sustainable implementation of bed nets-related programmes in Sub-Saharan Africa.

Construct validity of the bidding game, binary with follow-up, and a novel structured haggling question format in determining willingness to pay for insecticide-treated mosquito nets

This study examines whether making question formats better fit the cultural context of markets would improve the construct validity of estimates of willingness to pay (WTP). WTP for insecticide-treated mosquito nets was elicited using the bidding game, binary with follow-up (BWFU), and a novel structured haggling technique (SH) that mimicked price taking in market places in the study area. The results show that different question formats generated different distributions of WTP. Following a comparison of alternative models for each question format, construct validity was compared using the most consistently appropriate model across question formats for the positive WTP values, in this case, ordinary least squares. Three criteria (the number of statistically significant explanatory variables that had the anticipated sign, the value of the adjusted R(2), and the proportion that were statistically significant With the anticipated sign) used to assess the relative performance of each question format indicated that SH performed best and BWFU worst. However, differences in the levels of income, education, and percentage of household heads responding to the different question formats across the samples complicate this conclusion. Hence, the results suggest that the SH technique is worthy of further investigation and use.

Demand assessment and price-elasticity estimation of quality-improved primary health care in Palestine: a contribution from the contingent valuation method

This paper proposes a new methodology to assess demand and price-elasticity for health care, based on patients' stated willingness to pay (WTP) values for certain aspects of health care quality improvements. A conceptual analysis of how respondents consider contingent valuation (CV) questions allowed us to specify a probability density function of stated WTP values, and consequently, to model a demand function for quality-improved health care, using a parametric survival approach. The model was empirically estimated using a CV study intended to assess patients' values for improving the quality of primary health care (PHC) services in Palestine. A random sample of 499 individuals was interviewed following medical consultation in four PHC centers. Quality was assessed using a multi-attribute approach; and respondents valued seven specific quality improvements using a decomposed valuation scenario and a payment card elicitation technique. Our results suggest an inelastic demand at low user fees levels, and when the price-increase is accompanied with substantial quality-improvements. Nevertheless, demand becomes more and more elastic if user fees continue to rise. On the other hand, patients' reactions to price-increase turn out to depend on their level of income. Our results can be used to design successful health care financing strategies that include a consideration of patients' preferences and financial capacities.

Delivery of insecticide-treated net services through employer and community-based approaches in Kenya

BACKGROUND AND OBJECTIVES

Many approaches have been used to deliver insecticide-treated nets (ITNs) to African communities in different settings. Between 1992 and 2002, the African Medical and Research Foundation (AMREF), Kenya, used two ITN delivery models: the employer-based approach and the community-based approach. These two approaches have never been compared in order to inform their potential for future ITN delivery. We aimed to (1) compare the extent of ITN ownership, use and retreatment coverage in different population groups in the employer and community-based models and (2) identify options for improving people's acceptance and use of treatment/retreatment services.

METHODS

Qualitative and quantitative methods for data collection and analysis. A total of 2095 household heads were interviewed in the quantitative study, while purposively selected groups and key informants participated in the qualitative study.

RESULTS

Net coverage (both treated and untreated nets) and retreatment rates with insecticides were significantly higher at employer-based sites (54.3%) than at community-based sites (35.0%). Bed net ownership has increased significantly since the start of AMREF interventions in 1998 in employer-based sites (from 27% to 61.1%); in community-based sites, it has either decreased (urban area, from 29.0% to 16.5%) or increased (rural area, from 17.0% to 49.1%). Retreatment rates in all sites were negatively influenced by the lack of information, cash and availability of insecticides. Satisfaction with the form of payment and services delivered was higher in employer-based sites. This was attributed to employers providing credit for the purchase of nets and retreatment kits and the employers' medical teams giving information on malaria and making follow-up visits on workers who fell ill.

CONCLUSIONS

Employer-based delivery of ITNs was more successful than community-based delivery in attaining both high coverage with ITNs and higher rates of net retreatment. Methods used for the retreatment of nets, forms of payment and communication strategies should be convenient to communities. Organized community groups may continue to play an important role in remote rural areas.

Willingness to pay for cataract surgery in two regions of Tanzania

BACKGROUND

Knowing what rural populations are willing to pay for cataract surgery is essential if improvements in cost recovery in eye care service provision programmes are to take place. The authors sought to learn about willingness to pay for cataract surgery in two separate regions of Tanzania.

METHODS

Patients desiring cataract surgery were interviewed in Kilimanjaro Region and Iringa Region of Tanzania to learn how much they and their families were willing to pay for surgery and how "wealthy" (using ownership of several household objects as a proxy for wealth) the household was.

RESULTS

60 cataract patients in Kilimanjaro and 49 in Iringa were interviewed. "Wealth" was significantly associated with willingness to pay in each region. The average expressed willingness to pay was 2457Tsh (SD 4534) or approximately $US2.30, which is far below the actual cost of providing the service.

CONCLUSION

There were significant differences in the expressed willingness to pay between Iringa and Kilimanjaro patients, which may reflect differences in the services provided in the regions. Willingness to pay may increase as the population gains familiarity and trust in the service. It may also be increased by ensuring that pricing is uniform and clearly advertised throughout regions and by educating health workers and counselling patients about the real costs of providing high quality surgery. Offering "free" services to all may result in lower expressed willingness to pay.

Socio-economic inequity in demand for insecticide-treated nets, in-door residual house spraying, larviciding and fogging in Sudan

BACKGROUND

In order to optimally prioritize and use public and private budgets for equitable malaria vector control, there is a need to determine the level and determinants of consumer demand for different vector control tools.

OBJECTIVES

To determine the demand from people of different socio-economic groups for indoor residual house-spraying (IRHS), insecticide-treated nets (ITNs), larviciding with chemicals (LWC), and space spraying/fogging (SS) and the disease control implications of the result.

METHODS

Ratings and levels of willingness-to-pay (WTP) for the vector control tools were determined using a random cross-sectional sample of 720 householdes drawn from two states. WTP was elicited using the bidding game. An asset-based socio-economic status (SES) index was used to explore whether WTP was related to SES of the respondents.

RESULTS

IRHS received the highest proportion of highest preferred rating (41.0%) followed by ITNs (23.1%). However, ITNs had the highest mean WTP followed by IRHS, while LWC had the least. The regression analysis showed that SES was positively and statistically significantly related to WTP across the four vector control tools and that the respondents' rating of IRHS and ITNs significantly explained their levels of WTP for the two tools.

CONCLUSION

People were willing to pay for all the vector-control tools, but the demand for the vector control tools was related to the SES of the respondents. Hence, it is vital that there are public policies and financing mechanisms to ensure equitable provision and utilisation of vector control tools, as well as protecting the poor from cost-sharing arrangements.

Willingness-to-Pay and Demand Curves: A Comparison of Results Obtained Using Different Elicitation Formats

Health economists use "willingness-to-pay" to assess the prospective value of novel interventions. The technique remains controversial, not least with respect to the formats under which values are elicited. The paper analyses the results of a series of studies of the same intervention valued by the same population, in which different elicitation formats were employed. The findings support the hypothesis that data collected using different formats give rise to different demand curves, from which different inferences about demand elasticity, profitability and consumer surplus will be derived. Judgements as to the relative merits of rival interventions depend crucially upon whichever format has been used to evaluate each intervention.

Do divergences between stated and actual willingness to pay signify the existence of bias in contingent valuation surveys?

This study's objective is to determine the factors that cause divergences over time (differences) between stated willingness to pay (WTP) and actual WTP (purchase behaviour), and consider whether any divergence signifies the presence of bias in contingent valuation studies. Stated WTP for insecticide-treated bed-nets (ITNs) was elicited from a random sample of respondents using three question formats in Nigeria. The question formats were the bidding game (BG), binary with follow-up (BWFU) and a novel structured haggling (SH) technique. The sales of the nets and a second survey were conducted 1 month after the first survey. In the second survey, factors that might explain the divergences were built into the questionnaire and these together with socio-economic variables were examined for causes of divergences in WTP. Data were analysed using non-parametric tests, testing of means and cross-tabulations. There were divergences in WTP in all three question formats: 69.4% in the BG, 78.7% in the BWFU and 48.8% in the SH. The higher the stated WTP, the more likely the divergence between stated and actual WTP. The attitude of the community leaders to the ITNs in the BG (p<0.05), the time respondents had to think about their WTP (p<0.05) and the external information they received about the ITNs in the BWFU (p<0.05) all led to divergences in WTP. We conclude that there are genuine causes of divergences between stated and actual WTP across the three question formats, and that the lesser the criterion validity score, the more the level of divergence in WTP. Studies that compare stated and actual WTP should explicitly determine the causes of divergences in order to assess the role of bias in the divergences.

Willingness to pay for preventive travel health measures among Hong Kong Chinese residents

BACKGROUND

The effectiveness of preventive measures in combating travel-related illnesses is well recognized. However, there is a lack of information on the economic value of any travel-associated preventive measures in the literature.

OBJECTIVES

The purpose of this article is to report the values of willingness to pay (WTP) to prevent travel health problems in Hong Kong's travelers.

METHODS

A cross-sectional telephone survey for a sample of Hong Kong population was conducted in 1998 using a random digit dialing technique. The sample WTP values were elicited using an open-ended question. Logistic regression was performed to identify predictors of WTP. Mean WTP was estimated using Heckman's sample selection model on log-WTP.

RESULTS

Of the subjects interviewed, 77% (285/369) offered positive values of WTP to prevent travel health problems. The observable WTP (zero excluded) had a higher mean (447 Hong Kong dollars) than did the zero-inclusive data (351 Hong Kong dollars). The median values were 200 Hong Kong dollars in both cases because there were a large number of protest responses. Age, travel frequency, ability to assess travel health risk, precautionary behavior, and previous exposure to health protection materials explained one's willingness to pay a positive amount for preventing travel health problems. Age, education level, and precautionary behavior were predictors of the WTP levels.

CONCLUSION

The findings of this study suggest that Chinese travelers are willing to pay for the prevention of travel-related illnesses. The predictors of WTP identified could be used to suggest policy changes. However, future studies are needed to explore further the relationship between the experience of travel illnesses, the magnitude of travel health risks, and WTP.

Can we use contingent valuation to assess the demand for childhood immunisation in developing countries?: a systematic review of the literature

Childhood immunisation is one of the most cost-effective public health interventions, yet its population coverage in low- and middle-income countries is severely limited by the fiscal constraints that health services face. A recent proposal suggested that commitments to purchase vaccines and make them available to developing countries for modest co-payments could solve the problem. However, this is dependent on communities being willing and able to share the cost in this way, which is difficult to assess. One possible method to assess this demand is contingent valuation (CV). This article evaluates the usefulness of using CV in this way, by reviewing applications of CV in developing countries against current 'standards' for CV of immunisation in the literature. A structured review was adopted with reference to the standard frameworks for methodological evaluation. A set of five criteria were developed for evaluating an 'acceptable' CV study: (i) response rate; (ii) association between willingness to pay (WTP) and socioeconomic status (SES); (iii) sensitivity of WTP to benefit scale/scope; (iv) predictive validity; and (v) reliability in elicitation formats. Two strands of literature search were conducted using electronic databases (MEDLINE, EMBASE, HEALTHSTAR and Econlit) from 1966 to 2003, one for CV studies of immunisation and one for CV studies in developing countries. Twelve CV studies of vaccination and 13 CV studies undertaken within developing countries were identified and reviewed. The quality of existing CV studies conducted in developing countries exceeded the benchmark standard set by studies of immunisation in the developed world in four of the five criteria. WTP estimates appeared both internally valid (i.e. associations with SES) and externally valid (i.e. predictive validity), reliability in developing countries was no less than that of the benchmark level in the existing literature, and the high response rates suggested that CV can be administered to a rural, and perhaps less literate, population. Only sensitivity to scale/scope was not well demonstrated. Our assessment indicated that the CV technique offers a promising tool to estimate the demand for childhood immunisation in low- and middle-income countries. International agencies are therefore encouraged to devote resources to such an application when designing their support to the immunisation programmes.

A stated preference approach to assessing health care-quality improvements in Palestine: from theoretical validity to policy implications

User fees have been promoted as a potential complementary funding mechanism for health care in developing countries. In this paper, we appraise the use of contingent valuation (CV) as a tool to help develop user fees schemes that could be used to assist in allocating, and partially fund, health care. A random sample of 499 patients seeking care in primary health care centers, in Palestine, were asked to reveal their willingness to pay values for specified improvements in the quality of delivered medical care. Empirical analysis suggests that, in this context, CV can lead to internally consistent results and useful policy implications.

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

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 Coartem 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 Coartem 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.

Inequalities in purchase of mosquito nets and willingness to pay for insecticide-treated nets in Nigeria: challenges for malaria control interventions

Objective

To explore the equity implications of insecticide-treated nets (ITN) distribution programmes that are based on user charges.

Methods

A questionnaire was used to collect information on previous purchase of untreated nets and hypothetical willingness to pay (WTP) for ITNs from a random sample of householders. A second survey was conducted one month later to collect information on actual purchases of ITNs. An economic status index was used for characterizing inequity.

Major findings

The lower economic status quintiles were less likely to have previously purchased untreated nets and also had a lower hypothetical and actual WTP for ITNs.

Conclusion

ITN distribution programmes need to take account of the diversity in WTP for ITNs if they are to ensure equity in access to the nets. This could form part of the overall poverty reduction strategy.

Criterion and content validity of a novel structured haggling contingent valuation question format versus the bidding game and binary with follow-up format

Contingent valuation question formats that will be used to elicit willingness to pay for goods and services need to be relevant to the area they will be used in order for responses to be valid. A novel contingent valuation question format called the "structured haggling technique" (SH) that resembles the bargaining system in Nigerian markets was designed and its criterion and content validity compared with those of the bidding game (BG) and binary-with-follow-up (BWFU) technique. This was achieved by determining the willingness to pay (WTP) for insecticide-treated nets (ITNs) in Southeast Nigeria. Content validity was determined through observation of actual trading of untreated nets together with interviews with sellers and consumers. Criterion validity was determined by comparing stated and actual WTP. Stated WTP was determined using a questionnaire administered to 810 household heads and actual WTP was determined by offering the nets for sale to all respondents one month later. The phi (correlation) coefficient was used to compare criterion validity across question formats. The phi coefficients were SH (0.60: 95% C.I. 0.50-0.71), BG (0.42: 95% C.I. 0.29-0.54) and the BWFU (0.32: 95% C.I. 0.20-0.44), implying that the BG and SH had similar levels of criterion-validity while the BWFU was the least criterion-valid. However, the SH was the most content-valid. It is necessary to validate the findings in other areas where haggling is common. Future studies should establish the content validity of question formats in the contexts in which they will be used before administering questionnaires.

Altruistic willingness to pay in community-based sales of insecticide-treated nets exists in Nigeria

The objective of this study was to determine whether households who are willing to pay for insecticide-treated nets (ITNs) for themselves are prepared to contribute for the ITNs to be purchased for the indigent community members who cannot afford the nets. This was in the framework of community-based and directed sales for ITNs. The study was conducted in four malaria holoendemic communities in south-eastern Nigeria. Contingent valuation method was used to determine the altruistic willingness to pay (WTP) from randomly selected household heads or their representatives, which was elicited using an open-ended question. Theoretical validity was assessed using the Tobit model. Median altruistic WTP ranged from $0.11 to $0.21 across the four communities (95 Naira = $1). However, using a pooled data from the four communities, the mean was $0.34. In Tobit estimation, altruistic WTP varied significantly with two of the communities; the respondents were resident in, sex, marital status and the amount of savings of the respondent. It also varied significantly with the respondents' WTP for their own ITNs and average monthly household expenditures to treat malaria (p<0.05). Altruistic WTP will exist in community-based and directed sales of ITNs. Thus there can be intra-community subsidisation by the rich for the poor who may not be able to pay for the nets. Community mobilisation and sensitisation should be used to encourage able households to actually pay at least the amounts they have stated.