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

Valuation of Local Demand for Improved Air Quality: The Case of the Mae Moh Coal Mine Site in Thailand

While the district of Mae Moh, Thailand has been well known for its atmospheric pollution associated with coal power production, economic assessment of demand for improved air quality has not been conducted to date. This study estimated local residents’ individual and aggregate willingness to pay (WTP) for mitigation of atmospheric pollution in Mae Moh using the contingent valuation method (CVM), and analyzed the factors associated with the individual WTP using the bivariate tobit and double-hurdle regression techniques. Primary data were collected through face-to-face interviews with a stratified sample of 200 residents. The hypothetical scenarios used in the CVM module were 50% and 80% mitigation of atmospheric concentrations of major pollutants. The weighted average WTP was found to be THB 251.3 and 307.9 per annum (USD 8.4 and 10.3) for the 50% and 80% reduction scenarios, respectively. The aggregate WTP for the entire population of Mae Moh was THB 10,008,733 and 12,264,761 per annum (USD 336,294 and 412,096), respectively. Education, occupation type, income, expenses, satisfaction with ambient quality, and perceived sources of pollution had significant associations with the individual WTP. The paper concludes by discussing policy implications for atmospheric pollution management and avenues for future research.

Facilitators and barriers to completing recommended doses of pneumococcal vaccination among community-living individuals aged ≥65 years in Hong Kong - a population-based study

Individuals aged ≥65 y are recommended to receive pneumococcal vaccination (PV). PV completion is defined as receiving two doses of PV among those with at least one high-risk condition for severe invasive pneumococcal diseases (IPD) or receiving one dose of PV among those without any high-risk conditions. This study investigated factors associated with PV completion among a random sample of community-living older adults in Hong Kong, China. In addition, factors associated with receiving a single dose of PV among older adults with at least one high-risk condition were also investigated. A total of 750 community-living Chinese-speaking individuals aged ≥65 y in Hong Kong (response rate: 63.4%) completed a random telephone survey from May to July 2019. PV completion was 10% among all participants. Among participants with high-risk condition(s) for severe IPD, 11.4% received a single dose of PV. After adjustment for significant background variables, several Health Belief Model constructs were significantly associated with both dependent variables: (1) perceived risk of contracting pneumococcal diseases, (2) perceived benefits of PV for protecting themselves or others, (3) perceived barriers to PV uptake, (4) being suggested by significant others to take up PV (cue to action), and (5) confidence to take up PV (perceived self-efficacy). In addition, being knowledgeable about pneumococcal diseases and vaccination, and knowing at least one peer of similar age who had taken up PV were also positively associated with both dependent variables. Targeted, theory-based health promotion efforts are needed to increase PV coverage among elderly in Hong Kong.

Willingness to pay for oral cholera vaccines in urban Bangladesh

Introduction

Cholera is a highly infectious disease and remains a serious public health burden in Bangladesh. The objective of the study was to measure the private demand for oral cholera vaccines (OCV) in Bangladesh and to investigate the key determinants of this demand, reflected in the household’s willingness to pay (WTP) for oral cholera vaccine.

Methods

A contingent valuation method was employed in an urban setting of Bangladesh during December 2015 to January 2016. All respondents (N = 1051) received a description of World Health Organization (WHO) prequalified OCV, Shanchol^™. Interviews were conducted with either the head of households or their spouse or a major economic contributor of the households. Respondents were asked about how much at maximum they were willing to pay for OCV for their own and their household members’ protection. Results are presented as the average and median of the reported maximum WTP of the respondents with standard deviations and 95% confidence interval. Natural log-linear regression model was employed to examine the factors influencing participants’ WTP for OCV.

Results

About 99% of the respondents expressed WTP for OCV with a maximum mean and median WTP per vaccination (2 doses) of US$ 2.23 and US$ 1.92 respectively. On the household level with an average number of 4.62 members, the estimated mean WTP was US$ 10 (median: US$ 7.69) which represents the perceived demand for OCV of a household to vaccinate against cholera.

Conclusions

The demand of vaccination further indicates that there is a potential scope for recovering a certain portion of the expenditure of immunization program by introducing direct user fees for future cholera vaccination in Bangladesh. Findings from this study will be useful for the policy-makers to make decision on cost-recovery in future oral cholera vaccination programs in Bangladesh and in similar countries.

Contingent Valuation Studies in Orthopaedic Surgery: A Health Economic Review

BACKGROUND

A greater emphasis on providing high-value orthopaedic interventions has resulted in increased health economic reporting. The contingent-valuation method (CVM) is used to determine consumer valuation of the benefits provided by healthcare interventions. CVM is an important value-based health economic tool that is underutilized in orthopaedic surgery.

QUESTIONS/PURPOSES

The purpose of this study was to (1) identify previously published CVM studies in the orthopaedic literature, (2) assess the methodologies used for CVM research, and (3) understand how CVM has been used in the orthopaedic cost-benefit analysis framework.

METHODS

A systematic review of the literature using the MEDLINE database was performed to compile CVM studies. Search terms incorporated the phrase willingness to pay (WTP) or willingness to accept (WTA) in combination with orthopaedic clinical key terms. Study methodology was appraised using previously defined empirical and conceptual criteria for CVM studies.

RESULTS

Of the 160 studies retrieved, 22 (13.8%) met our inclusion criteria. The economics of joint arthroplasty (n = 6, 27.3%) and non-operative osteoarthritis care (n = 4, 18.2%) were the most common topics. Most studies used CVM for pricing and/or demand forecasting (n = 16, 72.7%); very few studies used CVM for program evaluation (n = 6). WTP was used in all included studies, and one study used both WTP and WTA. Otherwise, there was little consistency among included studies in terms of CVM methodology. Open-ended questioning was used by only ten studies (45.5%), a significant number of studies did not perform a sensitivity analysis (n = 9, 40.9%), and none of the studies accounted for the risk preference of subjects. Only two of the included studies applied CVM within a cost-benefit analysis framework.

CONCLUSION

CVM is not commonly reported in orthopaedic surgery and is seldom used in the context of cost-benefit analysis. There is wide variability in the methods used to perform CVM. We propose that CVM is an appropriate and underappreciated method for understanding the value of orthopaedic interventions. Increased attention should be paid to consumer valuations for orthopaedic interventions.

Government employees' perception of urban air pollution and willingness to pay for improved quality: a cross-sectional survey study in Nanchang, China

To improve the public's awareness of urban air pollution and promote establishment of more efficient policy toward urban air pollution, we investigated the government employees' perceptions of current urban air pollution and their willingness to pay (WTP) taxes for improved quality in Nanchang, China. Stratified cluster sampling strategy was used to distribute 629 questionnaires, and 608 were completed anonymously, yielding a 96.7 % response rate. Descriptive statistics frequencies and proportions were used to summarize the sample characteristics, and logistic regression models were performed to assess the associations of perception of urban air quality and WTP versus demographic variables. We found low awareness of urban air pollution (34.5 %) as well as low WTP (44.9 %), especially among the middle aged people (age 30-39 and age 40-49). Our study shows that female employees have better awareness of urban air pollution but much less willingness to pay for air quality improvement. Majority of the government employees showed their support to the government for more effective policies toward environmental protection, indicating more enhanced public education and environmental protection campaigns to improve the public's awareness of air pollution and work with every citizen to improve air quality. This study also obtained baseline information useful to the local regional and even national government in developing nations in their attempt to control urban air pollution in future.

Analysis of residents' willingness to pay to reduce air pollution to improve children's health in community and hospital settings in Shanghai, China

BACKGROUND

Shanghai, along with many major cities in China, faces deterioration of air quality and increases in air pollution-related respiratory diseases (RDs) in children due to rapid industrialization and urbanization. The Contingent Valuation Method (CVM) was used to qualitatively and quantitatively measure the willingness to pay (WTP) for reducing children's RDs through air quality improvement.

METHODS

Between April and May, 2014, 975 face-to-face interviews were collected from parents in a community-based and a hospital-setting in Shanghai. Multiple imputation and the Probit model were used to determine the relationship between the WTP and the related environmental factors, child health factors and the socio-economic status.

RESULTS

Most respondents reported being willing to make a financial contribution to improve air quality in both the community (52.6%) and hospital (70.2%) samples. Those in the hospital setting were willing to pay significantly more ¥504 (USD$80.7) compared to the community sample ¥428 ($68.5) as expected. Reasons for those not being willing to pay included lack of disposable income and believing that responsibility of the air quality was a community issue. These did not differ by sample. Annual household income and education were related to WTP.

CONCLUSION

This study indicated that parents in Shanghai would be willing to pay for improved air quality. Children's health can be the incentive for the citizens' participation and support in the air quality improvement, therefore, hospital settings may present unique places to improve education about air quality and enhance advocacy efforts. This study also suggested that future environmental policies be addressed more rigorously for targeted populations.

Determinants of willingness to pay for self-paid vaccines in China

BACKGROUND

While vaccines not covered by China's Expanded Program on Immunization can be received voluntarily with out-of-pocket payment, the uptake of self-paid vaccines in China is low.

OBJECTIVE

To investigate willingness to pay (WTP) for self-paid vaccines and its determinants in China.

METHODS

We interviewed 2160 randomly selected households with children 0-3 years old, in 108 communities from three provinces in 2013. A bidding game method was used to elicit WTP for two self-paid vaccines: 7-valent pneumococcal conjugate vaccine and influenza vaccine. We conducted multivariate linear regressions to determine factors affecting the WTP.

RESULTS

Median WTP for pneumococcal conjugate vaccine and influenza vaccine were Chinese Yuan 200 and 60 (10 US Dollars). 92% and 55% of respondents, respectively were not willing to pay the market price for these two vaccines. Lower price barrier and higher ability to pay were associated with higher WTP. Those with better vaccine or disease-related knowledge, higher perceived vulnerability and severity of diseases were willing to pay more. However, perceived effectiveness and safety barriers to vaccination had no significant effects on the WTP. Recommendations from peers and healthcare providers increased the WTP. Fathers and grand parents of children had a higher WTP than their mothers. The WTP decreased with age, but was not affected by education and occupation.

CONCLUSIONS

The majority of individuals, in our study, were not willing to pay the market price for self-paid vaccines against high-burden diseases in China. The economic barriers to vaccination should therefore be removed to increase the demand. Region-specific information about disease burden, fiscal capacity and cost-effectiveness is important for the development of local financing policy in order to cover vaccination costs. Interventions targeting psychosocial factors, such as health education and communication with providers and peers, could also be effective in increasing the uptake of these vaccinations.

Preferences for health outcomes associated with Group A Streptococcal disease and vaccination

BACKGROUND

A 26-valent Group A Streptococcus (GAS) vaccine candidate has been developed that may provide protection against pharyngitis, invasive disease and rheumatic fever. However, recommendations for the use of a new vaccine must be informed by a range of considerations, including parents' preferences for different relevant health outcomes. Our objectives were to: (1) describe parent preferences for GAS disease and vaccination using willingness-to-pay (WTP) and time trade-off (TTO) methods; and (2) understand how parents' implied WTP for a quality-adjusted life year (QALY) gained might vary depending on the particular health outcome considered (e.g. averted GAS disease vs. vaccine adverse events).

METHODS

Telephone interviews were conducted with parents of children diagnosed with GAS pharyngitis at 2 pediatric practice sites in the Boston metropolitan area. WTP and TTO (trading parental longevity for child's health) questions for 2 vaccine and 4 disease-associated health states were asked using a randomly selected opening bid, followed by a 2nd bid and a final open-ended question about the amount willing to pay or trade. Descriptive analyses included medians and interquartile ranges for WTP and TTO estimates. The Wilcoxon signed-rank test was used to assess differences in WTP/QALY values for vaccine adverse events vs. disease states.

RESULTS

Of 119 respondents, 100 (84%) and 96 (81%) provided a complete set of responses for WTP and TTO questions, respectively. The median WTP and discounted (at 3% per year) TTO values to avoid each health state were as follows: local reaction, $30, 0.12 days; systemic reaction, $50, 0.22 days; impetigo, $75, 1.25 days; strep throat, $75, 2.5 days; septic arthritis, $1,000, 6.6 days; and toxic shock syndrome, $3,000, 31.0 days. The median WTP/QALY was significantly higher for vaccine adverse events (approximately $60,000/QALY) compared to disease states ($18,000 to $36,000/QALY).

CONCLUSIONS

Parents strongly prefer to prevent GAS disease in children compared to vaccine adverse events. However, implied WTP/QALY ratios were higher for the prevention of vaccine adverse events. Regret for errors of commission vs. omission may differ and should be considered by vaccine policymakers.

Contingent valuation: what needs to be done?

Contingent valuation (CV) has been argued to have theoretical advantages over other approaches for benefit valuation used by health economists. Yet, in reality, the technique appears not to have realised these advantages when applied to health-care issues, such that its influence in decision-making at national levels has been non-existent within the health sector. This is not a result of a lack of methodological work in the area, which has continued to flourish. Rather, it is a result of such activities being undertaken in a rather uncoordinated and unsystematic fashion, leading CV to be akin to a 'ship without a sail'. This paper utilises a systematic review of the CV literature in health to illustrate some important points concerning the conduct of CV studies, before providing a comment on what the remaining policy and research priorities are for the technique, and proposing a guideline for such studies. It is hoped that this will initiate some wider and rigorous debate on the future of the CV technique in order to make it seaworthy, give it direction and provide the right momentum.

Comparison of four contingent valuation methods to estimate the economic value of a pneumococcal vaccine in Bangladesh

OBJECTIVES

To compare four contingent valuation elicitation methods as a means to estimate the value of a pneumococcal vaccine in Bangladesh and to test if the elicitation methods are subject to bias and if they produce valid responses.

METHODS

Three hundred sixty-one households with at least one child under 5 years of age were recruited in Dhaka, Bangladesh. Subjects were cluster-randomized to various elicitation methods: open-ended, dichotomous choice (at one of two asking prices), payment card (one of two cards with differing ranges). The dichotomous choice method was then followed up with a bidding game methodology, with the dichotomous choice price acting as the starting price for the bidding game. Analysis focused on summary statistics, demand curve estimation and multivariate regression analysis to test for validity and bias.

RESULTS

Thirty-one households refused to participate, leaving a total of 330 participating households (a 91.4 percent response rate). Willingness to pay estimates varied significantly across the methods (p < .001), with average estimates varying between $2.34 and $18 (US). The open-ended elicitation method was found to produce highly inflated values that were insensitive to construct validity tests. The dichotomous choice method produced quantity (demand) estimates rather than value estimates, and there was some evidence of yea-saying. The payment card elicitation method was found to be affected by range bias. The bidding game elicitation method was found to be less sensitive to starting point bias and yea-saying.

CONCLUSIONS

Different elicitation format do give rise to different demand curves; however, this may be partially due to the fact that they do not measure the same outcome. For example, the dichotomous choice format produces a demand curve, while the payment card, open-ended and bidding game produce inverse demand curves. All formats are prone to multiple biases. When choosing an elicitation format, it is important to first consider the purpose and use of the data. Each elicitation method has strengths and weaknesses and can be used for different purposes in technology assessment.

Use, option and externality values: are contingent valuation studies in health care mis-specified?

A general population sample of Australian respondents completed a contingent valuation (CV) survey that asked them to value six scenarios. These varied according to whether the scenario was seeking to elicit: (i) use value; (ii) externality value; (iii) option value; or (iv) a combination. Results indicate that use plus externality and/or option value was significantly greater than use value alone. As CV studies in health (care) overwhelmingly focus on use value alone - often implicitly through study design rather than explicitly - this raises the possibility of mis-specification in CV research in health (care). The implications for CV in health (care) are considered.

A 'league table' of contingent valuation results for pharmaceutical interventions: a hard pill to swallow?

Pharmaceutical expenditure represents a large percentage of total healthcare expenditure, and has thus received much attention within the economic evaluation literature. However, although the number of contingent valuation (CV) studies measuring willingness to pay (WTP) in healthcare has increased, little is known about the relative magnitude of values elicited across different interventions, diseases or countries, or the methodological comparability of these values. We address this gap by seeking to establish if it is feasible to use elicited WTP values in resource allocation, illustrated by attempting to compile a 'league table' of WTP values for pharmaceutical interventions. A review database was compiled for CV studies in healthcare published from January 1985 to December 2005. Of 210 studies identified, 40 considered pharmaceutical interventions. Values are presented as mean or median WTP values, adjusted where necessary to pound and $US for 2004/5. Lack of reporting in some instances of either the mean or median, together with heterogenous methods and infrequent reporting of costs, made 'league table' construction difficult. This raises questions about the use of existing studies for resource allocation decisions, despite the fact that most studies were seemingly undertaken for policy objectives. However, four interventions had more than one study, making it possible to compare the values elicited. The values elicited across studies were fairly consistent for two interventions (anti-hypertensive therapy and tumour necrosis factor [TNF]-alpha blockade for rheumatoid arthritis), whereas WTP values for insulin and post-operative emesis therapy were very divergent. No single methodological difference seemed to explain this pattern; however, the more methodological differences between studies the greater the likelihood of divergent values. A checklist, or minimum reporting set of information, is the first step towards improving the consistency of methods, and therefore values, published. In the longer term, a move towards the use of a reference case akin to that used for cost-utility studies would seem important if such studies are to be used for comparative purposes and thereby be relevant to resource allocation decision making.