Assessing the economic value of a new antidepressant. A willingness-to-pay approach

Prevalence of Missing Values and Protest Zeros in Contingent Valuation in Dental Medicine

Background: The number of contingent valuation (CV) studies in dental medicine using willingness-to-pay (WTP) methodology has substantially increased in recent years. Missing values due to absent information (i.e., missingness) or false information (i.e., protest zeros) are a common problem in WTP studies. The objective of this study is to evaluate the prevalence of missing values in CV studies in dental medicine, to assess how these have been dealt with, and to suggest recommendations for future research. Methods: We systematically searched electronic databases (MEDLINE, Web of Science, Cochrane Library, PROSPERO) on 8 June 2021, and hand-searched references of selected reviews. CV studies in clinical dentistry using WTP for valuing a good or service were included. Results: We included 49 WTP studies in our review. Out of these, 19 (38.8%) reported missing values due to absent information, and 28 (57.1%) reported zero values (i.e., WTP valued at zero). Zero values were further classified into true zeros (i.e., representing the underlying preference of the respondent) or protest zeros (i.e., false information as a protest behavior) in only 9 studies. Most studies used a complete case analysis to address missingness while only one study used multiple imputation. Conclusions: There is uncertainty in the dental literature on how to address missing values and zero values in CV studies. Zero values need to be classified as true zeros versus protest zeros with follow-up questions after the WTP elicitation procedure, and then need to be handled differently. Advanced statistical methods are available to address both missing values due to missingness and due to protest zeros but these are currently underused in dental medicine. Failing to appropriately address missing values in CV studies may lead to biased WTP estimates of dental interventions.

The prospective, 24-week assessment of cost-efficacy of and compliance to antidepressant medications in a rural setting (PACECAR) study

BACKGROUND

Anxiety and depression are common mental health disorders that are responsible for considerable societal burden. There are no data on cost-efficacy and medication compliance related to the treatment of these disorders in rural India.

MATERIALS AND METHODS

All consenting adults (n = 455) diagnosed with generalized anxiety or (unipolar) depressive disorders in Suttur village, Karnataka, were treated with open-label fluoxetine (20-60 mg/day), sertraline (50-150 mg/day), escitalopram (10-20 mg/day), desvenlafaxine (50-150 mg/day), duloxetine (30-90 mg/day), amitriptyline (75-150 mg/day), or clomipramine (75-150 mg/day) in a structured, monotherapy dosing plan. The study was nonrandomized and otherwise naturalistic. Patients were followed up every 4 weeks for 24 weeks. Study discontinuation was defined as medication noncompliance for 3 or more days or withdrawal due to treatment nonresponse.

RESULTS

There was substantial discontinuation (34.5%) in the first 4 weeks; 55.4% had discontinued by 12 weeks. Subsequently, only 11.2% discontinued treatment. Only 33.4% of the subjects tolerated the treatment, responded to it, and remained compliant for 24 weeks. Such successful completion was highest for escitalopram and desvenlafaxine (46%-47%) and lowest for clomipramine and amitriptyline (10%-14%). Adverse events were the most common reason for noncompliance with clomipramine and amitriptyline (45%-46%); the experience of sufficient improvement was the most common reason for noncompliance with the remaining drugs (28%-49%). Whereas the average cost of efficacious treatment for a continuous period of 24 weeks was lowest for fluoxetine, an examination of the cost-efficacy tradeoff suggested maximum advantage for escitalopram, sertraline, and desvenlafaxine. The cost-efficacy profile for amitriptyline and clomipramine was poor.

CONCLUSIONS

Reasons for noncompliance vary by drug class and need to be considered when prescribing antidepressant drugs. Escitalopram, sertraline, and desvenlafaxine perhaps have the most favorable 24-week cost-efficacy profile; tricyclics are poorly tolerated. Rural subjects need to be educated that treatment must be continued even after improvement is established.

What matters to patients? A systematic review of preferences for medication-associated outcomes in mental disorders

OBJECTIVE

To investigate patients' preferences for outcomes associated with psychoactive medications.

SETTING/DESIGN

Systematic review of stated preference studies. No settings restrictions were applied.

PARTICIPANTS/ELIGIBILITY CRITERIA

We included studies containing quantitative data regarding the relative value adults with mental disorders place on treatment outcomes. Studies with high risk of bias were excluded.

PRIMARY AND SECONDARY OUTCOME MEASURES

We restricted the scope of our review to preferences for outcomes, including the consequences from, attributes of, and health states associated with particular medications or medication classes, and process outcomes.

RESULTS

After reviewing 11 215 citations, 16 studies were included in the systematic review. These studies reported the stated preferences from patients with schizophrenia (n=9), depression (n=4), bipolar disorder (n=2) and attention deficit hyperactive disorder (n=1). The median sample size was 81. Side effects and symptom outcomes outnumbered functioning and process outcomes. Severe disease and hospitalisation were reported to be least desirable. Patients with schizophrenia tended to value disease states as higher and side effects as lower, compared to other stakeholder groups. In depression, the ability to cope with activities was found to be more important than a depressed mood, per se. Patient preferences could not consistently be predicted from demographic or disease variables. Only a limited number of potentially important outcomes had been investigated. Benefits to patients were not part of the purpose in 9 of the 16 studies, and in 10 studies patients were not involved when the outcomes to present were selected.

CONCLUSIONS

Insufficient evidence exists on the relative value patients with mental disorders place on medication-associated outcomes. To increase patient-centredness in decisions involving psychoactive drugs, further research-with outcomes elicited from patients, and for a larger number of conditions-should be undertaken.

TRIAL REGISTRATION NUMBER

PROSPERO CRD42013005685.

Framing the willingness-to-pay question: impact on response patterns and mean willingness to pay

In this study, respondents were randomly allocated to three variants of the payment card format and an open-ended format in order to test for convergent validity. The aim was to test whether preferences (as measured by willingness to pay additional tax) would be affected by framing the willingness-to-pay question differently. Results demonstrated that valuations were highly sensitive to whether respondents were asked to express their maximum willingness to pay per month or per year. Another important finding is that the introduction of a binary response filter prior to the payment card follow-up tends to eliminate the positive aspects of introducing a payment card and produces response patterns that are much in line with those of the open-ended contingent valuation format. However, although a filter will impact on the distribution of willingness-to-pay bids and on the rate of zero and protest bids, the overall impact on the welfare estimate is minor. The outcomes of this study indicate that valuations in the stated preference literature may be, at least in part, a function of the instrument designed to obtain the valuations.

Children's outcomes and parents' preferences for the induction and maintenance of anaesthesia for day-case surgery

Focal points

Valuing health in a racially and ethnically diverse community sample: an analysis using the valuation metrics of money and time

PURPOSE

Limited research in health valuation analyzes samples with high proportions of racial/ethnic minorities within the United States. The primary objective was to explore patterns of health valuation across race/ethnicity using the Collaborative Psychiatric Epidemiology Surveys. A secondary objective was to analyze whether mental health disorder and immigrant status were associated with these estimates.

METHODS

Health valuation questions using different metrics (time and money) were analyzed. Ordered logit models stratified across poor and moderate health tested differences by race/ethnicity, with mental health disorder and immigrant status as covariates.

RESULTS

Asians in moderate health and Latinos were willing to pay more for health than non-Latino whites. Asians in moderate health were willing to trade more time for health. Latinos in poor health were less willing to trade time and gave disproportionate zero-trade responses. Lifetime history of anxiety disorder was positively associated with both metrics. Immigrant status confounded money valuation for Asians in moderate health, and time valuation for Latinos in poor health.

CONCLUSIONS

Health valuation estimates vary across race/ethnicity depending upon the metric. Time valuation scenarios appear less feasible for Latinos in poor health. More research is necessary to understand these differences and the role of immigrant status in health valuation.

Methodological issues in the monetary valuation of benefits in healthcare

Economic evaluation is concerned with comparing the costs and benefits of competing healthcare interventions in order to efficiently allocate resources. Whilst valuing costs is important, the valuation of benefits represents one of the greatest challenges facing health economists. This review considers the different techniques available for the valuation of healthcare benefits in monetary terms, and more specifically the contingent valuation method and discrete choice experiments. This review identifies some of the key issues and debates that have been published in the literature concerning the application of the techniques to healthcare and highlights important areas for future research.

Identifying factors that affect patients' willingness to pay for inhaled insulin

Predictors of patients' willingness to pay for inhaled insulin are unknown. This study found patients with higher annual household income and those who were dissatisfied with their current insulin therapy were willing to pay for inhaled products.

BACKGROUND

Not all diabetes patients are receptive to taking injectable insulin and may therefore be noncompliant. Inhaled insulin has been shown to be as efficacious as subcutaneous insulin, but determinants of patients' willingness to pay (WTP) for inhaled insulin are unknown.

OBJECTIVES

The objective of this study was to determine the relationship between various patient characteristics and patient satisfaction variables with WTP for inhaled insulin.

METHODS

Exploratory cross-sectional study using a random sample of patients with diabetes from a national database. Data were collected using a mailed survey focusing on patient satisfaction with current insulin therapy, WTP, and general patient information. Any WTP (categorical) and the amount (continuous) patients were willing to pay were the 2 dependent variables in the study. Data were analyzed using SPSS v.15.0. Descriptive statistics as well as linear and logistic regression analyses were conducted.

RESULTS

One hundred twenty-eight patients responded. The logistic regression analysis indicated that annual household income (P=.038) and patient satisfaction (P=.002) predict WTP. Additionally, the current cost of insulin therapy (P=.009) and annual household income (P=.049) were found to predict the amount patients were willing to pay. On average, patients were willing to pay $55.49 out of pocket for inhaled insulin per month.

CONCLUSIONS

The out-of-pocket cost that patients were willing to pay was the same as the amount patients pay presently for their insulin and syringes. Although Exubera is no longer on the market, the study findings can have an impact on pharmaceutical companies working on new inhaled insulin products in their efforts to care for patients with diabetes.

Eliciting preferences for resource allocation in mental health care in Ireland

The proportion of total health care expenditure devoted to mental health care in Ireland, at just below 7%, is low relative to other countries. There have been few studies that have examined the relationship between public preferences for different kinds of health care expenditure and priority setting as undertaken by policy-makers and governments. This paper examines citizen's rankings and willingness to pay for a community-based mental health care programme in Ireland relative to two other programmes: cancer and elderly care. Respondents rank cancer as the most important programme, followed by elderly care and then mental health care. The contingent valuation survey demonstrated that people are willing to make significant tax contributions to new community-based services for people with mental health problems, counteracting the view sometimes expressed that people do not care at all about mental health care provision. However, the survey also found that people tend to value additional spending on mental health care lower than cancer and elderly care programmes.

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.

Patients' willingness to pay for anti-emetic treatment

BACKGROUND

Post-operative nausea and vomiting (PONV) is a common complication of anaesthesia. This study was conducted in 100 German and 100 Turkish patients scheduled for elective surgery under general anaesthesia to assess the amount patients were willing to pay for an anti-emetic that completely prevented PONV.

METHODS

Post-operatively, using Dixon's up and down method, patients completed an interactive computer questionnaire with a random starting point to determine how much of their own money they were willing to pay for a totally effective anti-emetic treatment.

RESULTS

On average, participants were willing to pay 65 euro in Germany and 68 euro in Turkey to avoid PONV. However, patients who actually experienced PONV were willing to pay larger amounts: 96 euro in Germany and 99 euro in Turkey. The amount patients were willing to pay was related to female sex, history of motion sickness, non-smoking status and better education.

CONCLUSIONS

Despite differences in political and cultural origin, health care system and financial background, the amount patients were willing to pay for an effective anti-emetic was similar in both Germany and Turkey to that reported previously for the USA.

Utility values and myopia in medical students in Singapore

PURPOSE

Although technologies to correct myopia have progressed in recent years, it is not known how cost-effective such technologies are. In this paper, utility values of myopic medical students in Singapore were ascertained as a first step to deriving weights for quality adjustment in future cost-effectiveness studies of such technologies.

METHODS

Students (n = 120) aged 18-22 years with myopia (spherical equivalent at least -0.5 D) from Singapore's sole medical school were recruited. Information on lifetime intention to undergo refractive surgery, contact lens use, proportion of waking time spent wearing corrective devices, and utility values using the time trade-off and standard gamble for death methods, were obtained.

RESULTS

The mean utility values for time trade-off and standard gamble were 0.97 (95% confidence interval 0.96-0.98, median 1.00) and 0.99 (95% confidence interval 0.98-0.99, median 1.00), respectively. Utility values were significantly higher among those who reported a probability of less than 50% that they would undergo refractive surgery within their lifetime, compared with those who reported a probability of 50% or more (means 0.98 vs. 0.95, P < 0.001).

CONCLUSION

Utility values in myopic medical students obtained in this study appear to be relatively high, compared with those obtained for other ophthalmic conditions.

Erectile dysfunction in spinal cord injury: a cost-utility analysis

BACKGROUND

There is a high incidence of erectile dysfunction after spinal cord injury. This can have a profound effect on quality of life. Treatment options for erectile dysfunction include sildenafil, intracavernous injections of papaverine/alprostadil (Caverject), alprostadil/papaverine/phentolamine ("Triple Mix"), transurethral suppository (MUSE), surgically implanted prosthetic device and vacuum erection devices. However, physical impairments and accessibility may preclude patient self-utilization of non-oral treatments.

METHODS

The costs and utilities of oral and non-oral erectile dysfunction treatments in a spinal cord injury population were examined in a cost-utility analysis conducted from a government payer perspective. Subjects with spinal cord injury (n=59) reported health preferences using the standard gamble technique.

RESULTS

There was a higher health preference for oral therapy. The cost-effectiveness results indicated that sildenafil was the dominant economic strategy when compared with surgically implanted prosthetic devices, MUSE(R) and Caverject. The incremental cost-utility ratios comparing sildenafil with triple mix and vacuum erection devices favoured sildenafil, with ratios less than CAN$20,000 per quality adjusted life year gained.

CONCLUSION

Based on this study, we conclude that sildenafil is a cost-effective treatment for erectile dysfunction in the spinal cord injury population.

Using patient characteristics and attitudinal data to identify depression treatment preference groups: a latent-class model

A latent-class model is used to identify and characterize groups of patients who share similar attitudes towards treating depression. The results predict the probability of preference-group membership on the basis of observable characteristics and answers to attitudinal questions. Understanding the types of preference groups that exist and a patient's probability of membership in each of the groups can help clinicians tailor the treatment to the patient and may increase patient adherence. One hundred four depressed patients completed a survey on attitudes towards treatment of Major Depressive Disorder. Analysis shows that treatment preferences vary among depressed patients. Three classes are identified that differ in their sensitivity to treatment costs and side effects. One class cares primarily about treatment effectiveness; side effects and the cost of treatment have little impact on this class's treatment decisions. Another class is highly sensitive to cost and side effects. A third class is somewhat sensitive to cost and side effects. Younger and male patients are more likely to be sensitive to treatment costs and side effects.

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.

The cost-benefit of cholinesterase inhibitors in mild to moderate dementia: a willingness-to-pay approach

OBJECTIVE

This study aimed to measure the economic value of cholinesterase inhibitors when used to treat Alzheimer's disease using the willingness-to-pay (WTP) approach and the framework of cost-benefit analysis.

METHODS AND STUDY DESIGN

A cost-benefit analysis using the WTP approach was employed. The study sample consisted of 28 nonprofessional caregivers of outpatients with mild to moderate dementia from Toronto, ON, Canada. The caregivers were presented with four scenarios. In the first scenario, scenario A, a hypothetical patient with mild dementia was stabilised with a cholinesterase inhibitor. In the second scenario, scenario A with adverse effects, the above patient (A) experienced adverse effects caused by the drug. In the third scenario, scenario B, the patient exhibited behavioural symptoms in addition to mild dementia, and both were stabilised with the drug. In the fourth scenario, scenario B with adverse effects, the above patient (B) experienced adverse effects caused by the drug. The caregivers were then asked what amount they would pay, in Canadian dollars, each year to buy the medication, assuming that they were the caregivers of the patient described. A multivariate regression analysis was performed to assess the relationship between the demographic data (including the caregiver's yearly income) and the WTP. The average WTP was also predicted for the general population and the elderly population of Canada using data from Statistics Canada, and these values were compared with the cost of the medication.

STUDY PERSPECTIVE

Nonprofessional caregiver perspective. All monetary values are 1999 values unless otherwise specified.

RESULTS

The mean yearly WTP was $Can4540 (95% CI 2334-6746) for scenario A, $Can3686 (95% CI 1530-5842) for scenario A with adverse effects, $Can5003 (95% CI 2661-7345) for scenario B and $Can4486 (95% CI 2222-6750) for scenario B with adverse effects. The WTP decreased when drug adverse effects were present (significantly in scenario A; p = 0.04), but did not significantly increase when behavioural symptoms were present and stabilised. In all scenarios, caregiver yearly income was the only significant predictor of WTP, in the direction expected. For all scenarios, the calculated WTPs from the regression analysis using our sample mean, the average Canadian population data and the elderly population data were all higher than the yearly cost of the cholinesterase inhibitors, with the net benefit ranging from $Can1723 to $Can4508.

CONCLUSIONS

The results of the study, from a small sample of nonprofessional caregivers, revealed that the caregivers are willing to pay more for cholinesterase inhibitors than the drugs cost, even when the adverse effects of the drugs are taken into consideration. This indicates a net benefit for cholinesterase inhibitors in the treatment of mild to moderate dementia from a consumer's point of view.

Use of willingness to pay to study values for pharmacotherapies for migraine headache

BACKGROUND

There is a wide range of therapeutic options for migraine headaches, yet little is known about how patients value different treatment alternatives nor how to tailor treatments to patients' preferences.

OBJECTIVE

Assess patients' preferences for outcomes of treatment of migraine headache based on their marginal willingness to pay (WTP) for treatment attributes.

MATERIALS AND METHODS

In an Internet-based study, we used computer software to measure participants' WTP for a hypothetical ideal drug (one that was 100% effective, worked quickly, and had no adverse effects) and for other hypothetical drugs, each with one "less than ideal" attribute of performance.

SUBJECTS

Two hundred fifty-seven self-identified migraineurs recruited via an Internet Web site.

RESULTS

A high proportion of participants in the study had symptoms consistent with migraine etiology of headache (99%). Median "out-of-pocket" monthly WTP cost for an ideal migraine therapy was 130 dollars. WTP was associated with participants' own migraine experience: severity of pain, frequency of headaches, and the types of medications used in the past. WTP was reduced when pharmaceuticals offered less benefit, ranging from a mean of 74% of ideal for treatments that failed to relieve nausea, to 43% of ideal in treatments associated with a 50% chance of a rebound headache.

CONCLUSIONS

There is wide variability in patients' strength of preference for different attributes of migraine therapy. Choice of therapy for migraine headache should be individualized based on patients' preferences. WTP measures appear to be a valid and feasible metric for quantifying treatment preferences for migraine therapies.

Consumer preference for dinoprostone vaginal gel using stated preference discrete choice modelling

OBJECTIVE

To assess consumer preference for two methods of induction of labour using stated preference discrete choice modelling. The methods of induction were artificial rupture of the membranes (ARM) plus oxytocin and dinoprostone (prostaglandin E(2)) vaginal gel, followed by oxytocin if necessary.

METHODS

Consumer preference was measured in terms of willingness to pay for each of the attributes. These attributes were the method of administration, place of care, length of time from induction to delivery, need for epidural anaesthetic, type of delivery and cost. Levels were assigned to each of the attributes. Pregnant women attending a public hospital antenatal clinic were asked to read a description of the two methods and then to choose between them in 18 different scenarios in which the levels of the attributes were varied.

RESULTS

Women were willing to pay 11 Australian dollars for a 1% reduction in the chance of needing oxytocin as well as the gel and 55 Australian dollars for every 1 hour reduction in the length of time from induction to delivery. For a 1% reduction in the chance of needing an epidural anaesthetic or Caesarean section, women expressed a willingness to pay of 20 Australian dollars and 90 Australian dollars, respectively. All estimates were obtained in 1998 and expressed in Australian dollars (1 Australian dollar = 0.63 US dollars).

CONCLUSION

Women valued the less invasive method of administration of the gel and the associated greater freedom of movement during labour. However, they valued the shorter time from induction to delivery associated with ARM plus oxytocin more highly. A policy which allows women access to the gel for up to two doses would accommodate this consumer preference.

Assessing the economic impact of adverse drug effects

Although most commonly used drugs cause adverse effects, some of them with potentially serious consequences, relatively little is known about their economic impact. The purpose of this review is to summarise information describing the cost of treatment of drug-induced adverse effects as an additional cost of pharmaceutical treatment. The focus of this study was limited to the overall economic impact of drug-related morbidity and to the economic analysis of a single class of drugs with different safety profiles. Several studies carried out in the US have investigated adverse drug effects experienced by hospitalised patients and their impact on hospital costs. Patients who developed adverse effects were hospitalised an average of 1.2-3.8 days longer than patients who did not, with additional hospital costs of $US2284-5640 per patient (2000 values). Other research studies in different countries have quantified the incidence and economic consequences of adverse drug effects that occur in the ambulatory setting and that generate hospital admission and emergency department visits. They have shown that preventable adverse effects constitute between 43.3% and 80% of all adverse outcomes leading to emergency visits and hospital admissions, and disproportionately increase healthcare costs. Finally, a recent estimation revealed that in the US the cost of problems linked to drug use in the ambulatory setting exceeded $US177 billion in the year 2000.NSAIDs constitute a widely used class of drugs and they are one of the leading drug classes in causing adverse effects. The acquisition costs of the drugs, as well as the costs for prevention and treatment of adverse effects, determine their cost-effectiveness ratio. Depending on the incidence and severity of adverse effects, the cost per adverse effect avoided ranges from $US215 to $US35 459 (2000 values). According to the contingent valuation methodology, willingness to pay to avoid or reduce the incidence of adverse effects is an indicator of the value individuals associate with the impact of such effects on their well-being. Individuals are willing to pay annually an average of $US240 and $US350, respectively, to avoid vomiting and gastrointestinal distress induced by NSAIDs. Although the results of the different studies reviewed are not strictly comparable because of differences in the severity of adverse effects, the perspective of the analysis, the cost data included and the cost component considered, the data show that, apart from the implications for health, a substantial quantity of resources are used to treat adverse effects.

Conjoint analysis of a new Chemotherapy: willingness to pay and preference for the features of raltitrexed versus standard therapy in advanced Colorectal Cancer

OBJECTIVE

To estimate the willingness to pay for a new chemotherapy, raltitrexed (Tomudex trade mark ) over conventional therapy with fluorouracil plus leucovorin (FU-LV) from the perspective of patients with advanced colorectal cancer. The study was part of the product's reimbursement application in Australia.

DESIGN AND METHODS

The key differences relevant to patients between the two therapies, frequency of administration and severity of mouth ulceration, were used to develop a self-administered questionnaire. A relatively new technique to healthcare, that of conjoint analysis (CA), was used to estimate willingness to pay and strength of preference. A discrete choice CA was used. Analysis was via a logit model with adjustment for the cluster effect (or intra-patient correlation).

STUDY PARTICIPANTS

Oncology nurses served as proxies for patients with advanced colorectal cancer.

RESULTS

The participation rate was 87% (62/71) with questionnaires from 56 respondents eligible for analysis. The CA method generated a mean incremental willingness to pay of 745 Australian dollars (dollar A; dollars US 507) per cycle of chemotherapy, comprising dollars A 550 (dollars US 374) and dollars A 195 (dollars US 133) for the toxicity and administration improvements, respectively (1998 values). Both features were related to preference with independent odds of 6.87 and 1.98, respectively, however only the toxicity attribute was a significantly related to preference. Subscription to private health insurance was the only significant demographic predictor identified, however, the homogeneous income structure of the respondents seems likely to have masked any significant income effect.

CONCLUSIONS

This study highlights the advantages of using CA in healthcare, where new therapies or treatments are often composed of a number of attributes. The CA allows both strength of preference and willingness to pay for individual treatment attributes to be estimated and can be used to assign statistical significance to these parameters.

Economic value to parents of reducing the pain and emotional distress of childhood vaccine injections

BACKGROUND

One reason that recommended childhood immunizations due at child health visits are deferred is to avoid the pain and emotional distress associated with the increasing number of injections required. This deferral leads to additional visits and costs and reduced immunoprotection against vaccine-preventable illnesses. To assess the economic value of combination vaccines that address this problem, we surveyed parents to determine the amount they would be willing to pay to avoid the pain and emotional distress experienced by their infants from injections.

METHODS

A self-administered questionnaire was completed within 24 h of the vaccinations by 294 parents of children ages 11/2 to 7 months receiving vaccine injections at 26 outpatient child health centers. The willingness-to-pay (WTP) method was used to estimate the intangible cost of the pain and emotional distress of the 1 to 4 injections their child had received. Parents were asked how much of their own money they would have paid to avoid these injections, without any compromise in the safety and efficacy of the vaccinations.

RESULTS

Wide variations in WTP amounts were observed, ranging from median values of $10 to $25 and average values of $57.06 to $79.28 to avoid the pain and emotional distress associated with eliminating all injections at visits in which one to four injections were administered. Parents placed greater value on reductions that avoided all injections than on reductions that avoided only some injections. Overall the median cost per injection avoided was $8.14, and the mean was $30.28.

CONCLUSIONS

Parents have strong preferences for limiting vaccine injections. The economic cost of the pain and distress associated with such injections, reflected in the amounts they report they would be willing to pay to avoid them, represents a substantial component of the cost of disease control through immunization.

Willingness to pay for periodontal therapy: development and testing of an instrument

OBJECTIVES

The objective of this study was to develop and test the feasibility and validity of a willingness to pay (WTP) tool in a dental setting.

METHODS

A questionnaire measured individuals' preferences among alternative treatments for periodontal disease and the maximum they would be willing to pay for their treatment of choice in terms of dental insurance premiums. The questionnaire provides detailed information, in probabilistic terms, of the risks and benefits of treatment choices for moderate to advanced adult periodontitis. It was pilot tested on 23 periodontal patients and 18 dental school faculty and staff.

RESULTS

The majority (92.6%) felt the questionnaire was an accurate representation of treatments and outcomes, establishing face and content validity. In terms of construct validity, four hypotheses were tested: (1) manipulation of the outcomes of the preferred treatment led to a predictable shift in preferences for 38 subjects (92.7%); (2) although periodontal patients were not more likely to choose periodontal surgery than nonpatients (P = .14), those with a history of surgery were more likely to choose surgery again (P = .06); (3) WTP was positively related to income level (P = .05); and (4) subjects were willing to pay more for coverage for themselves than for others. Periodontal surgery was the preferred treatment for moderate to advanced periodontal disease, and was more strongly preferred than other choices (i.e., a higher WTP) for all income groups. The intraclass correlation coefficient for treatment preferences was 0.95 (P < .001) and the kappa for WTP was 0.78 (P < .001).

CONCLUSION

This pilot study supports some of the criteria concerning validity of the WTP questionnaire to measure preferences for alternative periodontal therapies. Further testing on larger samples is required to confirm these results.

A multinational pharmacoeconomic evaluation of acute major depressive disorder (MDD): a comparison of cost-effectiveness between venlafaxine, SSRIs and TCAs

METHODS

We conducted a multinational pharmacoeconomic evaluation comparing the immediate release form of a new class of serotonin norepinephrine reuptake inhibitor (SNRI), venlafaxine IR to the selective serotonin reuptake inhibitors (SSRIs) and the tricyclic antidepressants (TCAs) in the treatment of acute major depressive disorder (MDD) in 10 countries (Germany, Italy, Netherlands, Poland, Spain, Sweden, Switzerland, United Kingdom, United States, and Venezuela). We designed a decision analytic model assessing the acute phase of MDD treatment within a 6-month time horizon. Six decision tree models were customized with country-specific estimates from a clinical management analysis, meta-analytic rates from two published meta-analyses, and a resource valuation of treatment costs representing the inpatient and outpatient settings within each country. The meta-analyses provided the clinical rates of success defined as a 50% reduction in depression scores on the Hamilton Depression Scale (HAM-D) or the Montgomery-Asberg Depression Rating Scale (MADRS). Treatment regimen costs were determined from standard lists, fee schedules, and communication with local health economists in each country. The meta-analytic rates were applied to the decision analytic model to calculate the expected cost and expected outcomes for each antidepressant comparator. Cost-effectiveness was determined using the expected values for both a successful outcome, and a composite measure of outcome termed symptom-free days. A policy analysis was conducted to examine the health system budget impact in each country of increasing the utilization of the most effective antidepressant found in our study.

RESULTS

Initiating treatment of MDD with venlafaxine IR yielded a lower expected cost compared to the SSRIs and TCAs in all countries except Poland in the inpatient setting, and Italy and Poland within the outpatient settings. The weighted average expected cost per patient varied from US$632 (Poland) to US$5647 (US) in the six-month acute phase treatment of MDD. The estimated total budgetary impact for each 1% of venlafaxine utilization, assuming a population of one million MDD patients, ranged from US$1600 (Italy) to US$29,049 (US).

CONCLUSIONS

Within the inpatient and outpatient treatment settings, venlafaxine IR was a more cost-effective treatment of MDD compared to the SSRIs and TCAs. Additionally, the results of this investigation indicate that increased utilization of venlafaxine in most settings across Europe and the Americas will have favorable impact on health care payer budgets. ADR, adverse drug reaction; CMA, clinical management analysis; ECT, electroconvulsive therapy; HAM-D, Hamilton Depression Scale; MADRS, Montgomery-Asberg depression rating scale; MDD, major depressive disorder; SFD, symptom-free day; SNRI, serotonin-norepinephrine reuptake inhibitor; SSRI, selective serotonin reuptake inhibitor; TCA, tricyclic antidepressant; WHO, world health organization.

Consumers' willingness to pay for pharmacy services that reduce risk of medication-related problems

OBJECTIVE

To measure willingness to pay (WTP) for pharmacists' services directed toward reducing the risk of medication-related problems and to determine factors that have a significant influence on WTP.

DESIGN

WTP was measured using a contingent valuation method that involved asking respondents about their maximum WTP for pharmacists' services using a self-administered questionnaire. Respondents' WTP through ex post (out of pocket) and ex ante (insurance premium) methods were measured using three hypothetical scenarios illustrating reductions in the risk of medication-related problems. Logistic regression and semilog regression were performed to evaluate the responses to the survey.

SETTING

Outpatient clinic of Robert Wood Johnson University Hospital and two physician offices located in New Jersey.

PARTICIPANTS

A convenience sample of 316 patients and/or family members, who visited the study site between March 1 and September 15, 1999, were included.

MAIN OUTCOME MEASURES

Amounts patients were willing to pay out of pocket or through insurance premiums for pharmacists' services.

RESULTS

The mean WTP out of pocket for pharmacy services ranged from $4.02 to $5.48 per prescription, depending on the level of risk reduction. Mean WTP through an increased insurance premium ranged from $28.79 to $36.29 per year. Overall, the average WTP for a pharmacist's consultation was $5.57, and WTP increased by $0.87 as counseling time increased by 1 minute. WTP was sensitive to changes in the magnitude of risk reduction in both ex post and ex ante scenarios. Income was positively related to WTP, but not to the level of statistical significance.

CONCLUSION

Respondents were willing to pay for pharmacists' services that reduce the risk of medication-related problems. Additional investigations to determine the factors that influence WTP for health care professionals' services are warranted.

Measurement of consumer preference for treatments used to induce labour: a willingness-to-pay approach

AIM: The purpose of the study was to assess the acceptability to consumers of two methods of induction of labour using a willingness-to-pay (WTP) approach. The methods compared were amniotomy plus oxytocin and prostaglandin E2 vaginal gel, followed by oxytocin if necessary. METHODS: A description of each method was presented, in questionnaire format, to pregnant women attending a public hospital ante-natal clinic. Women were asked to choose one of the two treatments, then give a valuation in dollar terms for both their preferred treatment and the alternative. RESULTS: It was found that 73.7% of patients preferred gel. The mean maximum WTP for amniotomy plus oxytocin was Aus$133 while that for gel was Aus$178 (P=0.0001). Those who chose amniotomy plus oxytocin were WTP 90% more for their preferred treatment compared with the alternative (Aus$180 vs. Aus$95). Similarly, those who preferred gel were WTP 90% more for their preferred treatment compared with the alternative (Aus$222 vs. Aus$119). CONCLUSION: Consumers were able to assess drug information provided on the two therapies, make an informed choice and to value that choice. Information obtained in this way, combined with information on costs, could be used in policy decision-making.

Willingness to pay as a measure of the benefits of mental health care

BACKGROUND: Decision-makers would benefit from being able to plan and evaluate mental health care interventions or programmes on the basis of costs and consequences that are measured in the same unit of measurement (money being the most convenient). Monetized quantification of the consequences of alternative interventions could be subsequently incorporated into cost-benefit allocation decisions. AIM: This paper provides an overview of the policy and research context within which willingness-to-pay survey techniques are located, together with a review of the main approaches used to date. We also highlight key issues in the application of these techniques and indicate areas of mental health research and policy that could benefit from their introduction. METHOD: Willingness-to-pay survey techniques are reviewed, and issues concerning their validity and application in the context of cost-benefit analyses of mental health policies are discussed. DISCUSSION: Different survey methods are available for generating willingness-to-pay data, the most common being the contingent valuation approach. An assessment of the validity of data generated by these alternative techniques is vital in order to ensure that they are consistent with the notion of economic preferences and values. IMPLICATIONS: The generation of valid and meaningful data on the monetized value of mental health outcomes would provide decision-makers with an improved evidence-based framework for resource allocation.

The contingent valuation method in health care

The contingent valuation method (CVM) is a survey-based, hypothetical and direct method to determine monetary valuations of effects of health technologies. This comprehensive review of CVM in the health care literature points at methodological as well as conceptual issues of CVM and on willingness to pay as a measure of benefits compared with other measures used in medical technology assessment. Studies published before 1998 were found by searching computerised databases and former review literature. Studies were included, when performing CVM using original data and meeting qualitative criteria. Theoretical validity of CVM was sufficiently shown and there were several indications of convergent validity. No results on criterion validity and only a few on reliability were found. There was widespread use of different elicitation formats, which make comparisons of studies problematic. Direct questions were seen problematic. First bids used in bidding games influenced the monetary valuation significantly (starting point bias). There were indications that the range of bids of payment cards also affected the valuation (range bias). However, no strategic bias was found. The influence of different states of valuation (ex-ante, ex-post) and of payment methods, as well as the possible aggregation of the results of decomposed scenarios rather than more complex holistic scenarios, were rarely investigated. Further methodological analysis and testing seems to be necessary before CVM may be used in health care decision making. Important research topics are the connection of assessment of different elicitation methods and criterion validity as well as tests on reliability according to methodological issues. Concerning conceptual issues, the analysis of the influence of different states of evaluation and of the status of the respondents as diseased or non-diseased, as well as the aggregation of results of decomposed scenarios, proved to be topics of further research.

What are cancer patients willing to pay for prophylactic epoetin alfa? A cost-benefit analysis

BACKGROUND

Anemia, one of the most common complications of cancer chemotherapy, has been managed with red blood cell (RBC) transfusions. As an alternative, the agent epoetin alfa has the potential to reduce the transfusion requirements of patients receiving cancer chemotherapy. To estimate the value that cancer patients place on the drug, an economic analysis using the concept of willingness to pay (WTP) was conducted.

METHODS

The method of WTP was used within the framework of a classical cost-benefit analysis to estimate the net cost or benefit of administering prophylactic epoetin alfa to cancer patients. This estimate included the direct cost of epoetin alfa administration and savings secondary to reduced RBC transfusions. A cohort of 100 cancer patients who received or were scheduled to receive cisplatin or noncisplatin chemotherapy (50 per group) were then interviewed to measure the maximum WTP (net benefit) that they experienced with epoetin alfa.

RESULTS

Regarding the benefits they would experience after 3 months of epoetin alfa administration, patients receiving cisplatin and noncisplatin therapy stated that they would be willing to pay an average of 587 U.S. dollars (U.S.$587) (95%CI: $300-$875) and U.S.$613 (95%CI: $324-$902), respectively. These benefits were then subtracted from the total cost of the drug when administered to patients receiving cisplatin (U.S.$3530) and noncisplatin (U.S.$3653) therapy. This produced a net incremental treatment cost of U.S.$2943 (95%CI: $2655-$3230) and U.S.$3039 (95%CI: $2750-$3328) for the respective treatment groups.

CONCLUSIONS

The results of the current study suggest that the routine administration of epoetin alfa to cancer patients receiving myelosuppressive chemotherapy is a highly resource-intensive treatment policy with modest benefit to patients. Additional research is required to identify high risk patient subgroups who would benefit most from the drug. [See editorial on pages 2427-9, this issue.]

Economic comparisons of the pharmacotherapy of depression: an overview

As many countries find that their health care expenditure is taking up an increasing proportion of their financial resources, economic aspects of care processes have become more important in the choice of optimal strategies. This review of the economic studies of the comparative treatment of depression shows that nearly every aspect of treatment has important economic consequences. Cost-of-illness studies have documented the high burden on society of this disorder, and the associated loss of productivity and work. Comparative cost-effectiveness/utility studies, the majority of which are based on modelling techniques, have consistently shown a better cost-effectiveness ratio of the newer antidepressants over more traditional tricyclic antidepressants (TCAs), when all therapy-related costs are taken into account.

Assessing the value of a new pharmaceutical. A feasibility study of contingent valuation in managed care

OBJECTIVES

The authors assessed the feasibility and construct validity of the contingent valuation method for measuring the monetary value to healthy enrollees in a health maintenance organization of a new drug, filgrastim, as prophylaxis against febrile neutropenia after chemotherapy treatment for cancer.

METHODS

A random sample of 220 enrollees from a closed-panel staff-model health maintenance organization who did not have cancer were interviewed. Chemotherapy, febrile neutropenia and filgrastim were described by video and decision board. Questions were asked in two different scenarios: (1) User-based: Assuming they were at the point of consumption and about to receive chemotherapy, what is the maximum they would be willing to pay to receive filgrastim? and (2) Insurance-based: Given they were at risk of cancer in the future, what is the maximum they would be willing to pay in additional monthly insurance premiums to add filgrastim to the plan? In a second insurance scenario where respondents were told that filgrastim was covered, what is the minimum reduction in premium that persons were willing to accept to relinquish coverage of the drug? A 2 x 2 factorial design was used to contrast two bidding algorithms to test for starting point bias and two 5-yearly prior risks of cancer, 1/200 versus 1/100. Main effects were tested by ANCOVA controlling for age, sex, health, and income.

RESULTS

Demographics of experimental cells were similar. No evidence was found of significant starting point bias. For user-based questions, as expected, willingness-to-pay increases with febrile neutropenia risk reduction, but at a declining marginal rate. Despite careful presentation of information to respondents, willingness-to-pay for insurance was higher in the lower prior risk group. Consistent with previous contingent valuation studies, the authors of the present study found evidence that willingness-to-accept exceeds willingness-to-pay for coverage of the same benefit.

CONCLUSIONS

An insurance-based contingent valuation study is feasible in a health maintenance organization. Construct validation evidence was encouraging, with the exception of the test for prior risk of cancer; however, this was a between-person contrast and may have been confounded by other factors.

Cost-benefit analyses in the health-care literature: don't judge a study by its label

OBJECTIVES

To assess whether health-care related economic evaluations labeled as "cost benefit analyses" (CBA) meet a contemporary definition of CBA methodology and to assess the prevalence of methods used for assigning monetary units to health outcomes.

DATA SOURCES

Medline, Current Contents, and HSTAR databases and reference lists of review articles, 1991-1995.

STUDY SELECTION

Economic analyses labeled as CBAs were included. Agreement on study selection was assessed. STUDY EVALUATION: CBA studies were classified according to standard definitions of economic analytical techniques. For those valuing health outcomes in monetary units (bona fide CBAs), the method of valuation was classified.

RESULTS

53% of 95 studies were reclassified as cost comparisons because health outcomes were not appraised. Among the 32% considered bona fide CBAs, the human capital approach was employed to value health states in monetary units in 70%. Contingent valuation methods were employed infrequently (13%).

CONCLUSIONS

Studies labeled as CBAs in the health-care literature often offer only partial program evaluation. Decisions based only on resource costs are unlikely to improve efficiency in resource allocation. Among bona fide CBAs, the human capital approach was most commonly used to valuing health, despite its limitations. The results of health-care related CBAs should be interpreted with extreme caution.

When do the "dollars" make sense? Toward a conceptual framework for contingent valuation studies in health care

There is growing interest in the application of cost-benefit analysis (CBA) as a technique for the economic evaluation of health care programs. A distinguishing feature of CBA is that costs and benefits are expressed in the same units of value--typically money. A popular method for estimating money values for health care programs is the use of willingness-to-pay (or accept) survey techniques known as contingent valuation. This paper presents a conceptual framework to help in the interpretation or design of contingent valuation studies in health care. To be consistent with the theory upon which CBA is built, the authors consider what types of questions should be asked of what populations. They conclude that studies undertaking contingent valuation should distinguish between compensating variation and equivalent variation, and recognize that respondents can be gainers or losers in utility and therefore should be asked willingness-to-pay (or accept) questions as appropriate. Current critical-appraisal guidance in the health care literature for CBA is poor and unlikely to offer useful demarcation between good and bad CBA studies. More work is needed exploring whether recently issued guidelines for contingent valuation in environment damage assessment are applicable to health care studies.