A cost utility analysis of treatment options for gallstone disease: methodological issues and results

Incremental net benefit of cholecystectomy compared with alternative treatments in people with gallstones or cholecystitis: a systematic review and meta-analysis of cost–utility studies

Introduction

Cholecystectomy is a standard treatment in the management of symptomatic gallstone disease. Current literature has contradicting views on the cost-effectiveness of different cholecystectomy treatments. We have conducted a systematic reappraisal of literature concerning the cost-effectiveness of cholecystectomy in management of gallstone disease.

Methods

We systematically searched for economic evaluation studies from PubMed, Embase and Scopus for eligible studies from inception up to July 2020. We pooled the incremental net benefit (INB) with a 95% CI using a random-effects model. We assessed the heterogeneity using the Cochrane-Q test, I2 statistic. We have used the modified economic evaluation bias (ECOBIAS) checklist for quality assessment of the selected studies. We assessed the possibility of publication bias using a funnel plot and Egger’s test.

Results

We have selected 28 studies for systematic review from a search that retrieved 8710 studies. Among them, seven studies were eligible for meta-analysis, all from high-income countries (HIC). Studies mainly reported comparisons between surgical treatments, but non-surgical gallstone disease management studies were limited. The early laparoscopic cholecystectomy (ELC) was significantly more cost-effective compared with the delayed laparoscopic cholecystectomy (DLC) with an INB of US$1221 (US$187 to US$2255) but with high heterogeneity (I2=73.32%). The subgroup and sensitivity analysis also supported that ELC is the most cost-effective option for managing gallstone disease or cholecystitis.

Conclusion

ELC is more cost-effective than DLC in the treatment of gallstone disease or cholecystitis in HICs. There was insufficient literature on comparison with other treatment options, such as conservative management and limited evidence from other economies.

PROSPERO registration number

CRD42020194052.

Quality of Life in Pediatric Minimally Invasive Surgery. Cost-Utility Analysis of Laparoscopic Versus Open Appendectomy

Background: Economic evaluation in health care is becoming increasingly important. Laparoscopic appendectomy (LAp) is one of the most frequent minimally invasive procedures in the pediatric population. The increased costs of this approach in any indication could be justified by proving its cost-utility in terms of health-related quality of life (HRQoL). We aim to perform a cost-utility analysis between open and LAp (open appendectomy [OAp] and LAp). Materials and Methods: We included the data of children operated for acute noncomplicated appendicitis, who agreed to answer a validated quality of life (QoL) questionnaire. Costs were calculated for each patient. We established a threshold for cost-effectiveness (λ) of 20,000 to 30,000€ per quality adjusted life year (QALY) according to previous research. Results: A total of 53 patients were included. Overall mean costs in the OAp were 758.98€ and in the LAp 1525.50€. The incremental cost-effectiveness ratio was 18,000€/QALY, under the threshold of cost-effectiveness, therefore favoring the laparoscopic approach as it improves HRQoL despite the costs. Conclusions: Economic evaluation studies in Pediatric Surgery are scarce and rarely measure outcomes in terms of QoL. This information is important in the decision-making process for institutions and health-care professionals. Our results encourage the use of laparoscopy in pediatric appendectomy to improve HRQoL in our patients.

A Head-to-Head Comparison of the Standard Quality-Adjusted Life Year Model With the Annual Profile Model

OBJECTIVES

The standard quality-adjusted life year (QALY) model (SQM) assumes time-utility independence within constant health states and additive independence when health varies over time. The validity of SQM has been challenged through reported violations of these assumptions. An alternative approach that relaxes these assumptions is to assign a single valuation to an entire health profile: an integral assessment of disease severity over time. Here, we compare SQM with the annual profile model (APM) and test SQM for additive independence.

METHODS

Eighty-two respondents valued 6 episodic conditions, including 4 of short duration, with SQM and APM, using the time trade-off method. Inter-rater reliability was assessed using intraclass correlation coefficients. Face validity was tested by asking respondents how well they were able to imagine the health states under SQM and APM. We calculated SQM QALY values for a 1-year time period, allowing for a direct comparison with APM values. For the short-term conditions we expected higher QALY values for SQM, violating additive independence.

RESULTS

APM showed higher interrater reliability (intraclass correlation coefficient of 0.53 vs 0.18, respectively) and better face validity than SQM, with 6% (APM) vs 21% (SQM) of all respondents reporting difficulties. Additive independence of SQM was violated in 5 of the 6 conditions (including the 4 short duration health states), with higher QALY values under SQM (mean difference 0.04).

CONCLUSION

The impact of short-term conditions is systematically underestimated under SQM when compared to a health profile model. APM is a less restrictive model and demonstrates better validity.

Conducting a Time Trade-Off Study Alongside a Clinical Trial: A Case Study and Recommendations

Time trade-off (TTO) is an established method in health economics to elicit and value individuals' preferences for different health states. These preferences are expressed in the form of health-state utilities that are typically used to measure health-related quality of life and calculate quality-adjusted life-years in an economic evaluation. The TTO approach to directly elicit health-state utilities is particularly valuable when generic instruments (e.g. EQ-5D) may not fully capture changes in utility in a clinical trial. However, there is limited guidance on how a TTO study should be conducted alongside a clinical trial despite it being a valuable tool. We present an account of the design and development of a TTO study within a clinical trial as a case study. We describe the development of materials needed for the TTO interviews, the piloting of the TTO materials and interview process, and recommendations for future TTO studies. This paper provides a practical guide and reference for future applications of the TTO method alongside a clinical trial.

Challenges in Valuing Temporary Health States for Economic Evaluation: A Review of Empirical Applications of the Chained Time Trade-Off Method

BACKGROUND

The time trade-off (TTO) technique is commonly used to elicit health state utilities. Nevertheless, when the health states being valued are temporary, the TTO approach may be unsuitable. A variant of TTO- chained TTO-has been suggested to be used when the health states are temporary, but little research has been done on how chained TTO should be conducted.

OBJECTIVES

To systematically review the use of chained TTO in valuing temporary health states.

METHODS

A systematic literature search was conducted using the following major databases: Ovid MEDLINE(R), Embase, EBM Reviews, and PsycINFO. Abstracts (full articles if necessary) were screened by two independent reviewers, with a third reviewer resolving any disagreements.

RESULTS

The resulting number of articles for review was low (n = 9). All the reviewed studies used face-to-face interviews, most had small sample sizes (<100), and all studies valued a small number of health states (<7), with time horizons typically ranging from 4 weeks to 1 year. All studies discussed methodological issues of using chained TTO, and some compared the results with those generated using other preference elicitation methods.

CONCLUSIONS

Chained TTO appears to be feasible, consistent, and responsive and allows the valuation of temporary health states that would improve the efficiency and accuracy of decision making in health and health care. Nevertheless, the evidence is limited due to the low number of relevant studies in the literature. Further research is needed to examine the performance and validity of chained TTO compared with conventional TTO in the valuation of temporary health states.

A Systematic Review of the Techniques Used to Value Temporary Health States

BACKGROUND

A broad literature on health state utility values exists, but compared with chronic health states (HSs), issues surrounding the valuation of temporary health states (THSs) have been poorly explored.

OBJECTIVES

To assess the methods used by previous studies to value HSs that are considered temporary so as to determine the strengths and limitations associated with various approaches and to inform future study designs.

METHODS

A systematic review was undertaken to explore the methods used, assess how the valuation was conducted for diseases that might lead to HSs deemed as temporary, and identify the challenges encountered in the valuation of THSs.

RESULTS

Of the 36 relevant studies, 22 were explicit that the HS being valued was temporary. Most of the studies used more than one technique (often incorporating both conventional and adapted approaches). In using adapted techniques, the primary challenge was identifying an appropriate intermediate "anchor" HS and the possibility of negative utilities.

CONCLUSIONS

There is no agreement on the most methodologically robust approach to THS valuation. Valuation is complex and important issues relating to the validity, practicality, and reliability of the techniques used were not adequately covered by most of the studies identified.

Valuing Meta-Health Effects for Use in Economic Evaluations to Inform Reimbursement Decisions: A Review of the Evidence

OBJECTIVE

This review explores the evidence from the literature regarding how meta-health effects (effects other than health resulting from the consumption of health care) are valued for use in economic evaluations.

METHODS

A systematic review of the published literature (the EMBASE, MEDLINE, PsycINFO, CINAHL, EconLit and SocINDEX databases were searched for publications in March 2016, plus manual searching) investigated the associations between study methods and the resulting values for meta-health effects estimated for use in economic evaluations. The review considered which meta-health effects were being valued and how this differed by evaluation approach, intervention investigated, source of funds and year of publication. Detailed reasons for differences observed between values for comparable meta-health effects were explored, accounting for the method of valuation.

RESULTS

The search of the literature revealed 71 studies of interest; 35% involved drug interventions, with convenience, information and process of care the three meta-health effects most often investigated. Key associations with the meta-health effects were the evaluation method, the intervention, and the source of funds. Relative values for meta-health effects ranged from 0.9% to 68% of the overall value reported in a study. For a given meta-health effect, the magnitude of the effect evaluated and how the meta-health effect was described and framed relative to overall health explained the differences in relative values.

CONCLUSIONS

Evidence from the literature shows variability in how meta-health effects are being measured for use in economic evaluations. Understanding the sources of that variability is important if decision makers are to have confidence in how meta-health effects are valued.

Cost-effectiveness of emergency versus delayed laparoscopic cholecystectomy for acute gallbladder pathology

BACKGROUND

The optimal timing of cholecystectomy for patients admitted with acute gallbladder pathology is unclear. Some studies have shown that emergency cholecystectomy during the index admission can reduce length of hospital stay with similar rates of conversion to open surgery, complications and mortality compared with a 'delayed' operation following discharge. Others have reported that cholecystectomy during the index acute admission results in higher morbidity, extended length of stay and increased costs. This study examined the cost-effectiveness of emergency versus delayed cholecystectomy for acute benign gallbladder disease.

METHODS

Using data from a prospective population-based cohort study examining the outcomes of cholecystectomy in the UK and Ireland, a model-based cost-utility analysis was conducted from the perspective of the UK National Health Service, with a 1-year time horizon for costs and outcomes. Probabilistic sensitivity analysis was used to investigate the impact of parameter uncertainty on the results obtained from the model.

RESULTS

Emergency cholecystectomy was found to be less costly (£4570 versus £4720; €5484 versus €5664) and more effective (0·8868 versus 0·8662 QALYs) than delayed cholecystectomy. Probabilistic sensitivity analysis showed that the emergency strategy is more than 60 per cent likely to be cost-effective across willingness-to-pay values for the QALY from £0 to £100 000 (€0-120 000).

CONCLUSION

Emergency cholecystectomy is less costly and more effective than delayed cholecystectomy. This approach is likely to be beneficial to patients in terms of improved health outcomes and to the healthcare provider owing to the reduced costs.

The QALY Model and Individual Preferences for Health States and Health Profiles over Time: A Systematic Review of the Literature

The numbers of quality-adjusted life years (QALYs) gained are increasingly being used to represent the gains in individual utility from treatment. This requires that the value of a health improvement to an individual is a simple product of gains in quality of life and length of life. The article reports on a systematic review of the literature on 2 issues: whether the value of a state is affected by how long the state lasts, and by states that come before or after it. It was found that individual preferences over health are influenced by the duration of health states and their sequence. However, although there is much variation across individual respondents, the assumptions tend to hold much better when valuations are aggregated across respondents, which is encouraging for economic evaluations that rely on using average (mean or median) values.

Clinical effectiveness and cost-effectiveness of cholecystectomy compared with observation/conservative management for preventing recurrent symptoms and complications in adults presenting with uncomplicated symptomatic gallstones or cholecystitis: a systematic review and economic evaluation

BACKGROUND

Approximately 10-15% of the adult population suffer from gallstone disease, cholelithiasis, with more women than men being affected. Cholecystectomy is the treatment of choice for people who present with biliary pain or acute cholecystitis and evidence of gallstones. However, some people do not experience a recurrence after an initial episode of biliary pain or cholecystitis. As most of the current research focuses on the surgical management of the disease, less attention has been dedicated to the consequences of conservative management.

OBJECTIVES

To determine the clinical effectiveness and cost-effectiveness of cholecystectomy compared with observation/conservative management in people presenting with uncomplicated symptomatic gallstones (biliary pain) or cholecystitis.

DATA SOURCES

We searched all major electronic databases (e.g. MEDLINE, EMBASE, Science Citation Index, Bioscience Information Service, Cochrane Central Register of Controlled Trials) from 1980 to September 2012 and we contacted experts in the field.

REVIEW METHODS

Evidence was considered from randomised controlled trials (RCTs) and non-randomised comparative studies that enrolled people with symptomatic gallstone disease (pain attacks only and/or acute cholecystitis). Two reviewers independently extracted data and assessed the risk of bias of included studies. Standard meta-analysis techniques were used to combine results from included studies. A de novo Markov model was developed to assess the cost-effectiveness of the interventions.

RESULTS

Two Norwegian RCTs involving 201 participants were included. Eighty-eight per cent of people randomised to surgery and 45% of people randomised to observation underwent cholecystectomy during the 14-year follow-up period. Participants randomised to observation were significantly more likely to experience gallstone-related complications [risk ratio = 6.69; 95% confidence interval (CI) 1.57 to 28.51; p = 0.01], in particular acute cholecystitis (risk ratio = 9.55; 95% CI 1.25 to 73.27; p = 0.03), and less likely to undergo surgery (risk ratio = 0.50; 95% CI 0.34 to 0.73; p = 0.0004), experience surgery-related complications (risk ratio = 0.36; 95% CI 0.16 to 0.81; p = 0.01) or, more specifically, minor surgery-related complications (risk ratio = 0.11; 95% CI 0.02 to 0.56; p = 0.008) than those randomised to surgery. Fifty-five per cent of people randomised to observation did not require an operation during the 14-year follow-up period and 12% of people randomised to cholecystectomy did not undergo the scheduled operation. The results of the economic evaluation suggest that, on average, the surgery strategy costs £1236 more per patient than the conservative management strategy but was, on average, more effective. An increase in the number of people requiring surgery while treated conservatively corresponded to a reduction in the cost-effectiveness of the conservative strategy. There was uncertainty around some of the parameters used in the economic model.

CONCLUSIONS

The results of this assessment indicate that cholecystectomy is still the treatment of choice for many symptomatic people. However, approximately half of the people in the observation group did not require surgery or suffer complications in the long term indicating that a conservative therapeutic approach may represent a valid alternative to surgery in this group of people. Owing to the dearth of current evidence in the UK setting a large, well-designed, multicentre trial is needed.

STUDY REGISTRATION

The study was registered as PROSPERO CRD42012002817.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Comparative economics of a 12-gene assay for predicting risk of recurrence in stage II colon cancer

BACKGROUND

Prior economic analysis that compared the 12-gene assay to published patterns of care predicted the assay would improve outcomes while lowering medical costs for stage II, T3, mismatch-repair-proficient (MMR-P) colon cancer patients. This study assessed the validity of those findings with real-world adjuvant chemotherapy (aCT) recommendations from the US third-party payer perspective.

METHODS

Costs and quality-adjusted life-years (QALYs) were estimated for stage II, T3, MMR-P colon cancer patients using guideline-compliant, state-transition probability estimation methods in a Markov model. A study of 141 patients from 17 sites in the Mayo Clinic Cancer Research Consortium provided aCT recommendations before and after knowledge of the 12-gene assay results. Progression and adverse events data with aCT regimens were based on published literature. Drug and administration costs for aCT were obtained from 2014 Medicare Fee Schedule. Sensitivity analyses evaluated the drivers and robustness of the primary outcomes.

RESULTS

After receiving the 12-gene assay results, physician recommendations in favor of aCT decreased 22 %; fluoropyrimidine monotherapy and FOLFOX recommendations each declined 11 %. Average per-patient drugs, administration, and adverse events costs decreased $US2,339, $US733, and $US3,211, respectively. Average total direct medical costs decreased $US991. Average patient well-being improved by 0.114 QALYs. Savings are expected to persist even if the cost of oxaliplatin drops by >75 % due to generic substitution.

CONCLUSIONS

This study provides evidence that real-world changes in aCT recommendations due to the 12-gene assay are likely to reduce direct medical costs and improve well-being for stage II, T3, MMR-P colon cancer patients.

The clinical investigation of disparity of utility values associated with gallstone disease: a pilot study

Purpose. The utility evaluation was an effective method to incorporate all of the contributing variables for multiple diseases into one outcome measure. A cross-sectional study was conducted to assess the utility values associated with varying states of gallstone disease among outpatient clinics participants at a teaching hospital in Taipei, Taiwan. Methods. The utility values were measured by using time trade-off method. A total of 120 outpatient clinics participants (30 subjects with no gallstone disease, 30 subjects with single stone, 30 subjects with multiple stones, and 30 subjects with cholecystectomy) evaluated utility values from January 1, 2006 to December 31, 2006. The diagnosis of gallstone disease was performed by a panel of specialists using ultrasound sonography. Results. The overall mean utility value was 0.89 ± 0.13 (95% CI: 0.87-0.91) indicating that study participants were willing to trade about 11% (95% CI: 9-13%) of their remaining life in return for being free of gallstone disease perpetually. The significant associated factors of utility values based on the multiple linear regression analysis were older age and different degrees of gallstone disease. Conclusion. Our results found that in addition to older age, multiple stones and cholecystectomy could influence utility values from the patient's preference-based viewpoint.

Incorporating process utility into quality adjusted life years: a systematic review of empirical studies

OBJECTIVE

This review aimed to identify published studies that provide an empirical measure of process utility, which can be incorporated into estimates of QALY calculations.

METHODS

A literature search was conducted in PubMed to identify published studies of process utility. Articles were included if they were written in the English language and reported empirical measures of process utility that could be incorporated into the QALY calculation; those studies reporting utilities that were not anchored on a scale of 0 representing dead and 1 representing full health were excluded from the review.

RESULTS

Fifteen studies published between 1996 and 2012 were included. Studies included respondents from the USA, Australia, Scotland and the UK, Europe and Canada. Eight of the included studies explored process utility associated with treatments; six explored process utility associated with screening procedures or tests; and one was performed in preventative care. A variety of approaches were used to detect and measure process utility: four studies used standard gamble techniques; four studies used time trade-off (TTO); one study used conjoint analysis and one used a combination of conjoint analysis and TTO; one study used SF-36 data; one study used both TTO and EQ-5D; and three studies used wait trade-off techniques. Measures of process utility for different drug delivery methods ranged from 0.02 to 0.27. Utility estimates associated with different dosing strategies ranged from 0.005 to 0.09. Estimates for convenience (able to take on an empty stomach) ranged from 0.001 to 0.028. Estimates of process utility associated with screening and testing procedures ranged from 0.0005 to 0.031. Both of these estimates were obtained for management approaches to cervical cancer screening.

CONCLUSION

The identification of studies through conventional methods was difficult due to the lack of consistent indexing and terminology across studies; however, the evidence does support the existence of process utility in treatment, screening and preventative care settings. There was considerable variation between estimates. The range of methodological approaches used to identify and measure process utility, coupled with the need for further research into, for example, the application of estimates in economic models, means it is difficult to know whether these differences are a true reflection of the amount of process utility that enters into an individual's utility function, or whether they are associated with features of the studies' methodological design. Without further work, and a standardised approach to the methodology for the detection and measurement of process utility, comparisons between estimates are difficult. This literature review supports the existence of process utility and indicates that, despite the need for further research in the area, it could be an important component of an individual's utility function, which should at least be considered, if not incorporated, into cost-utility analyses.

Is fidaxomicin worth the cost? An economic analysis

BACKGROUND

In May 2011, the Food and Drug Administration approved fidaxomicin for the treatment of Clostridium difficile infection (CDI). It has been found to be noninferior to vancomycin; however, its cost-effectiveness for the treatment of CDI remains undetermined.

METHODS

We developed a decision analytic simulation model to determine the economic value of fidaxomicin for CDI treatment from the third-party payer perspective. We looked at CDI treatment in these 3 cases: (1) no fidaxomicin, (2) only fidaxomicin, and (3) fidaxomicin based on strain typing results.

RESULTS

The incremental cost-effectiveness ratio for fidaxomicin based on screening given current conditions was >$43.7 million per quality-adjusted life-year and using only fidaxomicin was dominated (ie, more costly and less effective) by the other 2 treatment strategies explored. The fidaxomicin strategy tended to remain dominated, even at lower costs. With approximately 50% of CDI due to the NAP1/BI/027 strain, a course of fidaxomicin would need to cost ≤$150 to be cost-effective in the treatment of all CDI cases and between $160 and $400 to be cost-effective for those with a non-NAP1/BI/027 strain (ie, treatment based on strain typing).

CONCLUSIONS

Given the current cost and NAP1/BI/027 accounting for approximately 50% of isolates, using fidaxomicin as a first-line treatment for CDI is not cost-effective. However, typing and treatment with fidaxomicin based on strain may be more promising depending on the costs of fidaxomicin.

Intra-operative vs pre-operative endoscopic sphincterotomy in patients with gallbladder and common bile duct stones: cost-utility and value-of-information analysis

BACKGROUND

Patients with gallbladder and common bile duct stones are generally treated by pre-operative endoscopic sphincterotomy (ES) followed by laparoscopic cholecystectomy (POES). Recently, a meta-analysis has shown that intra-operative ES during laparoscopic cholecystectomy (IOES) results in fewer complications than POES, with similar efficacy. The cost effectiveness of IOES versus POES is unknown.

OBJECTIVE

The objective of this study was to compare the cost effectiveness of IOES versus POES from the UK NHS perspective.

METHODS

A decision-tree model estimating and comparing costs to the UK NHS and QALYs gained following a policy of either IOES or POES was developed with a time horizon of 3 years. Uncertainty was investigated with probabilistic sensitivity analysis, and the expected value of perfect information (EVPI) and partial information (EVPPI) were also calculated.

RESULTS

IOES was less costly than POES (approximately -£623 per patient [year 2008 values]) and resulted in similar quality of life (+0.008 QALYs per patient) as POES. Given a willingness-to-pay threshold of £20 000 per QALY gained, there was a 92.9% probability that IOES is cost effective compared with POES. Full implementation of IOES could save the NHS £2.8 million per annum. At a willingness to pay of £20 000 per QALY gained, the 10-year population EVPI was estimated at £0.6 million.

CONCLUSIONS

IOES appears to be cost effective compared with POES.

A test of independence of discounting from quality of life

The quality-adjusted life-years (QALY) model assumes quality and quantity of life can be multiplied into a single index and requires quality and quantity to be mutually independent, which need not hold empirically. This paper proposes a new test for measuring independence of utility of life duration from quality of life in a riskless setting. We use a large representative sample of Dutch citizens and include two health states generally considered better than dead (BTD) and one health state considered worse than dead (WTD). Independence cannot be rejected when comparing the BTD health states, but is rejected when comparing the BTD states with the WTD state. In particular, utility of life duration becomes more concave for the WTD state. This may suggest that independence holds only for BTD health states. This has implications for the QALY model and would require using sign-dependent utility of life duration functions.

Utilities and disutilities for attributes of injectable treatments for type 2 diabetes

INTRODUCTION

Although cost-utility models are frequently used to estimate treatment outcomes for type 2 diabetes, utilities are not available for key attributes of injectable treatments. The purpose of this study was to identify the utility or disutility of three injection-related attributes (dose frequency, dose flexibility, injection site reaction) that may influence patient preference.

METHODS

Patients with type 2 diabetes in Scotland completed standard gamble (SG) interviews to assess the utility of hypothetical health states and their own current health state. The EQ-5D, PGWB, IWQOL-Lite, and QIDS were also administered. Construct validity and differences among health states were examined.

RESULTS

A total of 151 patients completed interviews. Of the three injection-related attributes, dose frequency was the only attribute with a statistically significant impact on utility (in a multiple regression model, p = 0.01). Weekly injections were associated with an average added utility of 0.023 in comparison to everyday injections. Flexible dosing and injection site reactions resulted in somewhat smaller utility shifts that were in the expected directions (+0.006 and -0.011, respectively). SG utility of current health (mean = 0.897) demonstrated construct validity through statistically significant correlations with patient-reported outcome measures.

DISCUSSION

The three injection attributes were associated with small utility shifts in the expected directions. Dose frequency appears to be the most important of the three attributes from the patients' perspective. The vignette-based SG approach was feasible and useful for assessing added utility or disutility of injection-related attributes associated with treatments for type 2 diabetes.

Delayed assessment and eager adoption of laparoscopic cholecystectomy: Implications for developing surgical technologies

Despite the prevailing emphasis in the medical literature on establishing evidence, many changes in the practice of surgery have not been achieved using proper evidence-based assessment. This paper examines the adoption of laparoscopic cholecystectomy (LC) into regular use for the treatment of cholecystitis and the process of its acceptance, focusing on the limited role of technology assessment in its appraisal. A review of the published medical literature concerning LC was performed. Approximately 3000 studies of LC have been conducted since 1985, and there have been nearly 8500 publications to date. As LC was adopted enthusiastically into practice, the results of outcome studies generally showed that it compared favorably with the traditional, open cholecystectomy with regard to mortality, complications, and length of hospital stay. However, despite the rapid general agreement on surgical technique, efficacy, and appropriateness, there remained lingering doubts about safety, outcomes, and cost of the procedure that suggested that essential research questions were ignored even as the procedure became standard. Using LC as a case study, there are important lessons to be learned about the need for important guidelines for surgical innovation and the adoption of minimally invasive surgical techniques into current clinical and surgical practice. We highlight one recent example, natural orifice transluminal endoscopic surgery and how necessary it is to properly evaluate this new technology before it is accepted as a safe and effective surgical option.

On the (not so) constant proportional trade-off in TTO

Purpose

The linear and power QALY models require that people in Time Trade-off (TTO) exercises sacrifice the same proportion of lifetime to obtain a health improvement, irrespective of the absolute amount. However, evidence on these constant proportional trade-offs (CPTOs) is mixed, indicating that these versions of the QALY model do not represent preferences. Still, it may be the case that a more general version of the QALY model represents preferences. This version has the property that people want to sacrifice the same proportion of utilities of lifetime for a health improvement, irrespective of the amount of this lifetime.

Methods

We use a new method to correct TTO scores for utility of life duration and test whether decision makers trade off utility of duration and quality at the same rate irrespective of duration.

Results

We find a robust violation of CPTO for both uncorrected and corrected TTO scores. Remarkably, we find higher values for longer durations, contrary to most previous studies. This represents the only study correcting for utility of life duration to find such a violation.

Conclusions

It seems that the trade-off of life years is indeed not so constantly proportional and, therefore, that health state valuations depend on durations.

Measuring the quality-of-life effects of diagnostic and screening tests

Health-related quality of life (HRQL) is a central concept for understanding the outcomes of medical care. When used in cost-effectiveness analysis, HRQL is typically measured for conditions persisting over long time frames (years), and quality-adjusted life year (QALY) values are generated. Consequently, years are the basic unit of time for cost-effectiveness analysis results: dollars spent per QALY gained. However, shorter term components of health care may also affect HRQL, and there is increased interest in measuring and accounting for these events. In radiology, the short-term HRQL effects of screening and diagnostic testing may affect a test's cost-effectiveness, even though they may only last for days. The unique challenge in radiology HRQL assessment is to realistically tap into the testing and screening experience while remaining consistent with QALY theory. The authors review HRQL assessment and highlight methods developed to specifically address the short-term effects of radiologic screening and testing.

Methods for measuring temporary health States for cost-utility analyses

A variety of methods are available to measure preferences for temporary health states for cost-utility analyses. The objectives of this review were to summarize the available temporary health-state valuation methods, identify advantages and disadvantages of each, and identify areas for future research. We describe the key aspects of each method and summarize advantages and disadvantages of each method in terms of consistency with QALY theory, relevance to temporary health-state-specific domains, ease of use, time preference, and performance in validation studies. Two broad categories of methods were identified: traditional and adapted. Traditional methods were health status instruments, time trade-off (TTO), and the standard gamble (SG). Methods adapted specifically for temporary health-state valuation were TTO with specified duration of the health state, TTO with a lifespan modification, waiting trade-off, chained approaches for TTO and SG, and sleep trade-off. Advantages and disadvantages vary by method and no 'gold standard' method emerged. Selection of a method to value temporary health states will depend on the relative importance of the following considerations: ability to accurately capture the unique characteristics of the temporary health state, level of respondent burden and cognition, theoretical consistency of elicited preference values with the overall purpose of the study, and resources available for study development and data collection. Further research should focus on evaluating validity, reliability and feasibility of temporary health-state valuation methods.

Utilities and disutilities for type 2 diabetes treatment-related attributes

INTRODUCTION

Although cost-utility analyses are frequently used to estimate treatment outcomes for type 2 diabetes, utilities are not available for key medication-related attributes. The purpose of this study was to identify the utility or disutility of diabetes medication-related attributes (weight change, gastrointestinal side effects, fear of hypoglycemia) that may influence patient preference.

METHODS

Patients with type 2 diabetes in Scotland and England completed standard gamble (SG) interviews to assess utility of hypothetical health states and their own current health state. The EQ-5D, PGWB, and Appraisal of Diabetes Symptoms were administered. Construct validity and differences among health states were examined with correlations, t-tests, and ANOVAs.

RESULTS

A total of 129 patients (51 Scotland; 78 England) completed interviews. Mean utility of diabetes without complications was 0.89. Greater body weight was associated with disutility, and lower body weight with added utility (e.g., 3% higher = -0.04; 3% lower = +0.02). Gastrointestinal side effects and fear of hypoglycemia were associated with significant disutility (p < 0.001). SG utility of current health (mean = 0.87) demonstrated construct validity through correlations with patient-reported outcome measures (r = 0.08-0.31).

DISCUSSION

The vignette-based approach was feasible and useful for assessing added utility or disutility of medication-related attributes.

An economic evaluation of oxaliplatin for the adjuvant treatment of colon cancer in the United Kingdom (UK)

The MOSAIC study was the first trial to show a statistically significant disease-free survival benefit for a treatment regimen for stage III colon cancer in the adjuvant setting. At 4 years, there was a 25% reduction in the risk of disease recurrence in these patients for the combination of oxaliplatin/5-FU/FA compared with 5-FU/FA alone (p=0.002). This analysis evaluates the long-term cost effectiveness of oxaliplatin given in combination with 5-FU/FA from the perspective of the NHS in the United Kingdom (UK). The cost per quality-adjusted life-year gained over a lifetime was calculated using patient level data from the MOSAIC trial. Trial data were available for a median of 4 years of follow-up, these data were then extrapolated to a lifetime horizon. The estimated incremental lifetime cost per quality-adjusted life-year of oxaliplatin/5-FU/FA compared with 5-FU/FA alone in patients with stage III postoperative colon cancer is pound 4805. This compares favourably with other accepted interventions in oncology.

Cost-effectiveness analysis of oxaliplatin compared with 5-fluorouracil/leucovorin in adjuvant treatment of stage III colon cancer in the US

BACKGROUND

The MOSAIC trial demonstrated that oxaliplatin/5-fluorouracil/leucovorin (FU/LV) (FOLFOX4) as adjuvant treatment of TNM stage II and III colon cancer significantly improves disease-free survival compared with 5-FU/LV alone. For stage III patients the 4-year disease-free survival (DFS) was 69% in the FOLFOX4 arm vs 61% in the LV5FU2 arm, P = .002). The cost-effectiveness of FOLFOX4 in stage III patients was evaluated from a US Medicare perspective.

METHODS

By using individual patient-level data from the MOSAIC trial (median follow-up: 44.2 months), DFS and overall survival (OS) were estimated up to 4 years from randomization. DFS was extrapolated from 4 to 5 years by fitting a Weibull model and subsequent survival was estimated from life tables. OS beyond 4 years was predicted from the extrapolated DFS estimates and observed survival after recurrence. Costs were calculated from trial data and external estimates of resources to manage recurrence.

RESULTS

Patients on FOLFOX4 were predicted to gain 2.00 (95% confidence interval [CI]: 0.63, 3.37) years of DFS over those on 5-FU/LV. The predicted life expectancy of stage III patients on FOLFOX4 and 5-FU/LV was 17.61 and 16.26 years, respectively. Mean total lifetime disease-related costs were $56,300 with oxaliplatin and $39,300 with 5-FU/LV. Compared with 5-FU/LV, FOLFOX4 was estimated to cost $20,600 per life-year gained and $22,800 per quality-adjusted life-year (QALY) gained, discounting costs and outcomes at 3% per annum.

CONCLUSIONS

FOLFOX4 is likely to be cost-effective compared with 5-FU/LV in the adjuvant treatment of stage III colon cancer. The incremental cost-effectiveness ratio compares favorably with other funded interventions in oncology.

Recombinant erythropoietin for chemotherapy-related anaemia: economic value and health-related quality-of-life assessment using direct utility elicitation and discrete choice experiment methods

OBJECTIVE

To assess both the health-related quality of life (HR-QOL) and the economic value of erythropoietin treatment in chemotherapy-related anaemia using direct utility elicitation and discrete choice experiment (DCE) methods from a societal perspective in the UK.

METHODS

The time trade-off (TTO) method was employed to obtain utility values suitable for the calculation of QALYs for no, mild, moderate and severe anaemia. Health-state descriptions were developed using the Functional Assessment of Cancer Therapy - Anaemia (FACT-AN) subscale and the EQ-5D questionnaires, and were validated by clinical experts and patients. In addition, a DCE was implemented to elicit preferences for various anaemia treatment scenarios. The DCE analysis comprised important aspects of treatment identified from a literature review and by consultation with expert clinicians and cancer patients. The DCE included cost as an attribute in order to elicit willingness-to-pay (WTP) values (pound, 2004 values). The two methods were applied in the same cross-sectional sample of 110 lay people. Face-to-face interviews were conducted between February and March 2004.

RESULTS

The mean utility scores were 0.86 (standard error [SE] 0.014) for the no-anaemia state, and 0.78 (SE 0.016), 0.61 (SE 0.020) and 0.48 (SE 0.020) for the mild, moderate and severe anaemia states, respectively. The DCE results revealed the following preferences as significant predictors of choice: higher level of relief from fatigue, lower duration of administration, subcutaneous/intravenous administration versus cannula injection, GP versus hospital location, lower risk of infection or allergic reactions and lower cost per month to the patient. Attribute levels were valued higher for recombinant erythropoietin than for blood transfusion; this is reflected in an incremental welfare value of 368 pounds (95% CI 318, 419).

CONCLUSIONS

The results highlight a societal view that the severity of chemotherapy-related anaemia will significantly affect cancer patients' HR-QOL. The DCE survey shows that the public value favourably the attributes of treatment with recombinant erythropoietin, and indicates a likely patient preference for treatment with recombinant erythropoietin over blood transfusion.

Process utility in breast biopsy

PURPOSE

To determine whether the waiting trade-off (WTO) is feasible for differentiating short-term biopsy preferences in an acute situation where anxiety is the symptomatic disease state.

METHODS

75 women with past experience of either breast core-needle biopsy (CNB), more invasive excisional surgical biopsy (EXB), or both, had telephone WTO assessments. Patients' baseline and test-related anxiety were valued by time trade-off (TTO) used to scale the WTO. Rating scales (RS) were obtained for convergent validity assessment with WTO and TTO.

RESULTS

Data were obtained in 38 women who had both CNB and EXB ("paired") and 20 who had CNB only and 16 who had EXB only ("unpaired"). Patients rated only the procedure(s) they experienced. Median paired and mean unpaired WTO scores indicated patients were willing to wait significantly longer to avoid EXB (P = 0.0003, P = 0.0002, respectively). The waiting time difference between EXB and CNB was 2.1 weeks greater in unpaired data than paired data. RS scores comparing the procedures were significantly different only for paired data (P < 0.05). Median TTO preferences for baseline (1.00) and test anxiety (0.93) obtained in 74 patients were significantly different (P < 0.0001) and consistent with RS. Correlation was noted between WTO and RS (-0.307 to -0.453, P = 0.0205 to 0.0001). The median EXB quality-adjusted life years toll (1.5 quality-adjusted life days) calculated from pooled WTO data (paired and unpaired) from 54 patients is near a threshold in a published model.

CONCLUSION

The WTO is feasible for discriminating preferences for short-term health states in an acute medical scenario where it might have been expected to be impracticable.

Value of magnetic resonance cholangiopancreatography in the diagnosis of biliary abnormalities in postcholecystectomy patients: a probabilistic cost-effectiveness analysis of diagnostic strategies

BACKGROUND

Endoscopic retrograde cholangiopancreatography (ERCP) is considered the gold standard for imaging of the biliary tract but is associated with complications. Less invasive imaging techniques, such as magnetic resonance cholangiopancreatography (MRCP), have a much lower complication rate. The accuracy of MRCP is comparable to that of ERCP, and MRCP may be more effective and cost-effective, particularly in cases for which the suspected prevalence of disease is low and further intervention can be avoided. A model was constructed to compare the effectiveness and cost-effectiveness of MRCP and ERCP in patients with a previous history of cholecystectomy, presenting with abdominal pain and/or abnormal liver function tests.

METHODS

Diagnostic accuracy estimates came from a systematic review of MRCP. A decision analytic model was constructed to represent the diagnostic and treatment pathway of this patient group. The model compared the following two diagnostic strategies: (i) MRCP followed with ERCP if positive, and then management based on ERCP; and (ii) ERCP only. Deterministic and probabilistic analyses were used to assess the likelihood of MRCP being cost-effective. Sensitivity analyses examined the impact of prior probabilities of common bile duct stones (CBDS) and test performance characteristics. The outcomes considered were costs, quality-adjusted life years (QALYs), and cost per additional QALY.

RESULTS

The deterministic analysis indicated that MRCP was dominant over ERCP. At prior probabilities of CBDS, less than 60 percent MRCP was the less costly initial diagnostic test; above this threshold, ERCP was less costly. Similarly, at probabilities of CBDS less than 68 percent, MRCP was also the more effective strategy (generated more QALYs). Above this threshold, ERCP became the more effective strategy. Probabilistic sensitivity analyses indicated that, in this patient group for which there is a low to moderate probability of CBDS, there was a 59 percent likelihood that MRCP was cost-saving, an 83 percent chance that MRCP was more effective with a higher quality adjusted survival, and an 83 percent chance that MRCP had a cost-effectiveness ratio more favorable than dollars 50,000 per QALY gained.

CONCLUSIONS

Costs and cost-effectiveness are dependent upon the prior probability of CBDS. However, probabilistic analysis indicated that, with a high degree of certainty, MRCP was the more effective and cost-effective initial test in postcholecystectomy patients with a low to moderate probability of CBDS.

Watchful waiting after endoscopic removal of common bile duct stones: cheaper and better?

Drake et al. constructed a decision model to compare, in an older population, the costs and 2-yr survival rates of elective cholecystectomy versus expectant management after endoscopic removal of common bile duct (CBD) stones. The base case analysis indicated that the expectant management strategy dominated (less expensive and more effective) the elective surgery strategy. Sensitivity analysis suggested that the two strategies likely had equivalent effectiveness and that results were sensitive to the rate of recurrent biliary symptoms. Patient preferences for the different strategies (i.e., utilities) were not included in the model but are important to elicit and consider in clinical practice.

Is it worth offering a routine laparoscopic cholecystectomy in developing countries? A Thailand case study

OBJECTIVE

The study aims to investigate whether laparoscopic cholecystectomy (LC) is a cost-effective strategy for managing gallbladder-stone disease compared to the conventional open cholecystectomy (OC) in a Thai setting.

DESIGN AND SETTING

Using a societal perspective a cost-utility analysis was employed to measure programme cost and effectiveness of each management strategy. The costs borne by the hospital and patients were collected from Chiang Rai regional hospital while the clinical outcomes were summarised from a published systematic review of international and national literature. Incremental cost per Quality Adjusted Life Year (QALY) derived from a decision tree model.

RESULTS

The results reveal that at base-case scenario the incremental cost per QALY of moving from OC to LC is 134,000 Baht under government perspective and 89,000 Baht under a societal perspective. However, the probabilities that LC outweighed OC are not greater than 95% until the ceiling ratio reaches 190,000 and 270,000 Baht per QALY using societal and government perspective respectively.

CONCLUSION

The economic evaluation results of management options for gallstone disease in Thailand differ from comparable previous studies conducted in developed countries which indicated that LC was a cost-saving strategy. Differences were due mainly to hospital costs of post operative inpatient care and value of lost working time. The LC option would be considered a cost-effective option for Thailand at a threshold of three times per capita gross domestic product recommended by the committee on the Millennium Development Goals.

Assessment of health state utilities for attention-deficit/hyperactivity disorder in children using parent proxy report

This study used standard gamble (SG) utility interviews to assess parent preferences for health states of childhood attention-deficit/hyperactivity disorder (ADHD). Health state utilities are needed to calculate quality-adjusted life years (QALYs), a critical outcome measure in cost-effectiveness studies of new treatments. Parents (n = 43) of children diagnosed with ADHD completed SG utility interviews, rating their child's current health and 11 hypothetical health states describing untreated ADHD and ADHD treated with a stimulant or non-stimulant. Parents completed questionnaires on their children's symptoms and health-related quality of life (HRQL). Parents' SG rating of their child's current health state (mean of 0.74 on a utility scale ranging from 0 to 1) was significantly correlated with inattentive, hyperactive, and overall ADHD symptoms (r = 0.37, 0.36, and 0.40 respectively; p < 0.05) and psychosocial HRQL domains. Hypothetical health state utilities ranged from 0.48 (severe untreated ADHD) to 0.88 (effective and tolerable non-stimulant treatment). Comparisons between health states found expected differences between untreated mild, moderate, and severe ADHD health states. When both treatments were effective and tolerable, parents preferred the non-stimulant health state over the stimulant health state (p < 0.03). Results suggest that parent SG interviews are a feasible and useful method for obtaining utility scores that can be used in cost-effectiveness models of ADHD treatment.

Health state utilities for childhood attention-deficit/hyperactivity disorder based on parent preferences in the United kingdom

OBJECTIVES

The purpose of this study was to use standard gamble (SG) utility interviews to assess parent preferences for health states of childhood attention-deficit/hyperactivity disorder (ADHD).

METHODS

The study was conducted in August 2003 in London, England. Parents (N=83) of children diagnosed with ADHD completed SG utility interviews, rating their child's current health and 14 hypothetical health states describing untreated ADHD and ADHD treated with a nonstimulant, immediate-release stimulant, or extended-release stimulant. Raw temporary utilities ranging from 0 (worst health) to 1 (best health) were adjusted to a chronic utility scale ranging from 0 (death) to 1 (best health) using a linear transformation. Parents rated the severity of their children's ADHD symptoms using the Attention-Deficit/Hyperactivity Disorder Rating Scale-IV (ADHD-RS) and their children's health-related quality of life using the EuroQol EQ-5D.

RESULTS

Raw and adjusted SG ratings of hypothetical health states ranged from 0.63-0.90 and 0.88-0.96, respectively. Parents' raw SG scores of their child's current health state (mean=0.72) were significantly correlated with inattentive, hyperactive, and overall ADHD symptoms (r=-0.25, -0.27, -0.27; P <0.05) and the EQ-5D visual analogue scale (r=0.26; P <0.05).

CONCLUSION

This UK-based study suggests that parent SG interviews are a valid method for obtaining utilities for child ADHD-related health states. The utilities obtained in this study would be appropriate for use in a cost-utility analysis evaluating the costs and benefits of childhood ADHD treatments in the United Kingdom.

A comparison of 3 valuation methods for temporary health states in patients treated with oral anticoagulants

BACKGROUND

The application of the time tradeoff (TTO) method in temporary health states may lead to less valid results because an unrealistic scenario is presented to patients. The chained TTO has been proposed to solve this problem.

OBJECTIVES

To compare a chained TTO method with a conventional TTO method in the valuation of temporary health states, in terms of consistency and reliability. To compare both TTO methods with direct rating.

PATIENTS AND METHODS

Eighty-four patients treated with oral anticoagulants were interviewed twice. During the 1st interview, values for 5 temporary health states were obtained with a rank ordering procedure, direct rating, and the chained TTO method. During the 2nd interview, either the 1st interview was repeated (n = 30) or health state values were obtained with the conventional TTO method (n = 54). Consistency was assessed by comparing the 3 valuation methods with the rank ordering procedure. Generalizability theory was used to assess reliability.

RESULTS

The 3 methods produced significantly different valuations of health states. Chained TTO values were higher than values obtained with direct rating and the conventional TTO. Consistency and reliability did not differ across the 3 methods.

CONCLUSION

The authors found no evidence for a difference in consistency and reliability between the chained TTO method and the conventional TTO method in the valuation of temporary health states. As direct rating is simpler to administer than both TTO methods, one could consider using direct ratings for the valuation of temporary health states. Biases associated with the conventional and the chained TTO method are discussed.

Process utility for imaging in cerebrovascular disease

RATIONALE AND OBJECTIVES

The morbidity associated with a diagnostic test can influence its cost-effectiveness, but the quantification of that morbidity is controversial. Accounting for pain and invasiveness requires the measurement of "process utility" in addition to the expected value of testing. An original time trade-off variant was applied to the imaging evaluation of cerebrovascular disease, for which differences in morbidity are important to patients.

MATERIALS AND METHODS

A "waiting trade-off" (WTO) was used to evaluate the preferences of 89 patients for magnetic resonance (MR) angiography and conventional x-ray angiography. Patients were experienced with both tests. A weighted difference was calculated between the period a patient was willing to wait for a test result and treatment after a hypothetical "ideal" test and the choice to undergo conventional angiography or MR angiography with immediate treatment. A rating scale was used to check the convergent validity of the WTO.

RESULTS

Paired data showed a highly significant difference (P = .0001) between the mean preference for conventional and MR angiography, favoring the latter and translating into a difference of 5 quality-adjusted life days. The more negatively patients judged their conventional angiographic experience, the longer they were willing to wait for the ideal test result.

CONCLUSION

The WTO provides a reasonable estimate of the relative morbidity of more invasive conventional angiographic procedures and provides a quality-adjustment term for economic analysis. Such an approach may enable more complete evaluation of the effects of other processes on medical care.

A population-based cohort study comparing laparoscopic cholecystectomy and open cholecystectomy

OBJECTIVES

Laparoscopic cholecystectomy (LC) has become a popular alternative to open cholecystectomy (OC). Previous studies comparing outcomes in LC and OC used small selected cohorts of patients and did not control for comorbid conditions that might affect outcome. The aims of this study were to characterize the morbidity, mortality, and costs of LC and OC in a large unselected cohort of patients.

METHODS

We used the population-based North Carolina Discharge Abstract Database (NCHDAD) for January 1, 1991, to September 30, 1994 (n = 850,000) to identify patients undergoing OC and LC. We identified the indications for surgery, complications, and type of perioperative biliary imaging used. We compared length of stay, hospital charges, complications, morbidity, and mortality between OC and LC patients. To account for variations in outcomes from differences in age and comorbidity between the OC and LC groups, we used the age-adjusted Charlson Comorbidity Index in regression analyses quantifying the association between type of surgery and outcome.

RESULTS

Our cohort consisted of 43,433 patients (19,662 LC and 23,771 OC). The mean age-adjusted Charlson Comorbidity Index score was slightly higher for the OC compared to the LC group (4.3 vs 4.1, p < 0.05). The OC patients had longer hospitalizations, generated more charges ($12,125 vs $9,139, p < 0.05), and required home care more often. The crude risk ratio comparing risk of death in OC to LC was 5.0 (95% CI = 3.9-6.5). After controlling for age, comorbidity, and sex, the odds of dying in the OC group was still 3.3 times (95% CI = 1.4-7.3) greater than in the LC group. In the LC group, the number of patients with acute cholecystitis rose over the study period, whereas the number of patients with chronic cholecystitis declined. In the OC group, the number of patients with acute and chronic cholecystitis declined. The use of intraoperative cholangiography was greater in the OC group but declined in both groups over the study period. The use of ERCP was greater in the LC group and increased in both groups over time.

CONCLUSIONS

The introduction of LC has resulted in a change in the management of cholecystitis. Despite a higher proportion of patients with acute cholecystitis, the risk of dying was significantly less in LC than in OC patients, even after controlling for age and comorbidity. Based on lower costs and better outcomes, LC seems to be the treatment of choice for acute and chronic cholecystitis.

Cost-effectiveness analysis of interferon beta in multiple sclerosis: a Markov process analysis

OBJECTIVE

The objective of this study was to examine the cost-effectiveness of preventive treatment with interferon beta (IFNB) versus no preventive treatment in patients with multiple sclerosis.

METHODS

The setting for this study was the United Kingdom. A lifetime Markov process model was constructed to model the average quality-adjusted life years (QALYs) and the costs of both treatment strategies. Data for the construction of the model came from published literature, including large multicenter randomized clinical trials in relapsing-remitting and secondary progressive multiple sclerosis. Costs were obtained from published sources.

RESULTS

The results of the baseline analysis from the National Health Service (NHS) perspective showed that the use of interferon beta as preventive treatment for MS increased the total average discounted cost from 51,214 Pounds to 221,436 Pounds per patient. The undiscounted effectiveness increased from 24.9 QALYs to 28.2 QALYs, resulting in an incremental cost-effectiveness ratio of 51,582 Pounds per QALY. Sensitivity analyses showed the robustness of this model for other interferons.

CONCLUSION

The study showed that preventive treatment with interferon beta in patients with multiple sclerosis may not be fully justified from a health-economic perspective, although interferon beta is associated with an improved effectiveness compared with no preventive treatment.

Changing methods of imaging the common bile duct in the laparoscopic cholecystectomy era in Western Australia: implications for surgical practice

OBJECTIVE

To assess changes in the use of endoscopic retrograde cholangiopancreatography (ERCP), intraoperative cholangiography (IOC), and surgical exploration of the common bile duct (CBD) associated with the introduction of laparoscopic cholecystectomy (LC).

SUMMARY BACKGROUND DATA

The optimal strategy for dealing with potential stones of the CBD during LC remains controversial.

METHODS

The authors conducted a population-based study of all cases of cholecystectomy (20,084) in Western Australia in the periods before, during, and after the introduction of LC (1988-1994). Index admissions were linked to previous or subsequent admissions for ERCP. Factors associated with ERCP were analyzed by multivariate regression models.

RESULTS

Between 1988 and 1994, admissions for ERCP almost doubled, whereas the use of IOC decreased from 71% to 51%. Different trends were found for open and laparoscopic procedures. Exploration of the CBD declined because of the infrequent use of this procedure in LC. Preoperative ERCP was significantly more common in older patients and men; the reverse was found for IOC. There was an adjusted 3.5-fold increase in preoperative ERCP both during and after the introduction of LC. The adjusted odds ratios for IOC were 0.48 and 0.52 for these periods.

CONCLUSIONS

The introduction of LC was associated with increasing reliance on ERCP to image the CBD and a decrease in the use of IOC. These changes were observed in both LC and open cholecystectomy. They suggest that the use of ERCP before cholecystectomy has partly replaced IOC for visualization of the CBD for suspected stones. Although more than 40% of patients undergoing LC had IOC, surgeons appear to be reluctant to perform surgical exploration of the CBD when stones are present. Savings in terms of both complications and cost can be expected if preoperative ERCPs performed for suspicion of uncomplicated CBD stones are replaced by IOC.

Economics of surgery

The time has come to subject surgery to the same rigours of economic assessment that other health-care sectors are already receiving--namely, the comparative assessment of costs and benefits. The surgical management of gallstones provides a good example of the role of economics in surgery. Gallstone disease is common and patients are usually referred to a surgeon, but the threshold for intervention is not agreed and varies widely, with considerable implications for resources. Gallstone removal has been subject to much innovation over the past 10 years, yet economic assessment of laparoscopic and "mini" cholecystectomy and of gallstone lithotripsy is rare, despite the fact that operation rates have increased by up to 50% in some countries. For surgery to compete with other interventions, economic assessment of new surgical techniques will be increasingly important. This assessment should be based on well-conducted clinical trials in which interventions are provided in a routine service setting, and in which benefits are assessed among other things on the basis of the patient's perceived quality of life. Economic assessment often needs data beyond those collected in a clinical trial, however pragmatic the trial design, so modelling will often be required, incorporating a range of sources of evidence. Finally, evidence alone will not be enough to promote cost-effective practices. The take-up of surgical techniques will always be affected by the way hospitals and surgeons are remunerated. Affecting practice requires a realistic system of reimbursement that reflects evidence on cost effectiveness.

Culture, self-rated health and resource allocation decision-making

It has been observed that some groups in society tend to report their health to be better than would be expected through more objective measures. The available evidence suggests that while variations in self-assessed measures of health may act as good proxies of mortality and morbidity in homogeneous populations, in some groups, such as the Aboriginal and Torres Strait Islander communities of Australia, these subjective measures may provide a misleading picture. Useful insights into the formation of health perceptions can be drawn from a range of disciplines, in particular, from social comparison theories, models of illness behaviour, survey literature and linguistics. These theories and models help to provide an understanding of the different ways in which illness may be perceived, evaluated and acted upon by different kinds of people. Such considerations can have very direct implications for those planning and evaluating public health programs as well as those responsible for funding such programs.

The role of a pre-scored multi-attribute health classification measure in validating condition-specific health state descriptions

It is common to find specially constructed condition-specific health state descriptions used as the basis for benefit assessment in cost-utility analysis. For this approach to be valid it is necessary to have valid descriptors of health states. Yet the evidence demonstrating descriptive validity has been neglected in economic evaluation. This paper reports on the validity, reliability and feasibility of obtaining values from specially constructed condition-specific descriptions of breast cancer screening by mapping these descriptions into a pre-scored multi-attribute health classification measure (the EuroQol instrument) and comparing the values obtained with those derived from a time trade-off exercise. In doing so, it highlights the importance of descriptive validity in explaining why different valuation methods produce different results. Four descriptions typically associated with ex post true negative, false positive, true positive and false negative breast screening results were considered.

Finding bile duct injuries using record linkage: a validated study of complications following cholecystectomy

Laparoscopic cholecystectomy was introduced to Western Australia in 1991 and has become the method of choice for this procedure, although there are concerns about complications, particularly bile duct injuries. Previous studies have investigated this problem but have not confirmed the accuracy of coded information. We used Record Linkage to link operative admissions to subsequent admissions for all people who underwent cholecystectomy between 1988 and 1994. Using ICD9-CM discharge codes, we identified patients with an associated complication. We validated these patients' medical notes to obtain the proportion of complications in the period encompassing the introduction of laparoscopic cholecystectomy. We found 48 bile duct injuries in 413 patients. Of these 43% were found using complication codes on the operative admission, 79% using linked records of subsequent admissions, and 90% by adding lists of complicated cases from the three teaching hospitals. Any epidemiological research that uses surgical complication codes from operative admissions, particularly in the absence of a specific ICD9-CM code, will lead to significantly underestimating the prevalence of complications. By using record linkage, and validating medical records, we captured a significant proportion of complications.

The measurement of indirect costs in the health economics evaluation literature. A review

In this paper we develop a framework to categorize the concepts used to estimate indirect costs in economic evaluation. We apply this framework in a literature review of economic evaluation studies. We searched all English language literature from 1994-96. Following the application of a search algorithm, which yielded 25 articles, we abstracted information from these articles to determine the methods used to identify the relative contribution of indirect costs of the cost-effectiveness ratio, the time horizon selected by the authors, the identification of those activities that were foregone, the time given up by these activities, and the valuation placed on this time. These methods were then assessed. Indirect costs, as they have been measured, significantly influence efficiency ratios. A wide variation exists among studies in how they incorporate each of the components of indirect costs. All of the four components that were identified will affect the measurement of indirect cost. Future guidelines in this area should address the entire measurement process.

Valuing temporary and chronic health states associated with breast screening

The aim of this study was to derive quality of life values for the four key breast screening outcomes (true negative, false positive, true positive and false negative), including the quality of life effects of the screening and treatment processes. In doing so, methodological issues in health status measurement were explored, in particular the valuation of temporary health states. The true negative and false positive descriptions were temporary health states, lasting for short term durations (12 months) and the true positive and false negative outcomes were chronic health states lasting for long term durations (rest of life). Descriptions of breast screening outcomes were valued using the time trade-off technique and the visual analogue scale. Paired comparisons between TTO values for states with the same duration found a difference between the true negative and the false positive time trade-off values but no difference for true positive and false negative descriptions. The TTO values for the false positive were low. The study highlights several important methodological issues such as the use of the two stage procedure for valuing temporary health states, the impact of duration on values, the impact of anchor points, and the importance of qualitative analysis of respondents values. Further empirical testing of all these issues is recommended.

Costs and effectiveness of extracorporeal gallbladder stone shock wave lithotripsy versus laparoscopic cholecystectomy. A randomized clinical trial. McGill Gallstone Treatment Group

Thirty-five patients were randomized to extracorporeal shock-wave lithotripsy (ESWL) and 25 to laparoscopic cholecystectomy (LC). Stone disappearance occurred in only 12 of 32 ESWL patients [38% (95% CI: 21-56%)] during a 15-month follow-up. Greater incremental gains in quality of life after 6 months were observed among LC patients (p < .01). Total duration of disability was 6.8 +/- 8.5 days for ESWL, and 22.7 +/- 16.6 days for LC (p < .01). Nine (28%) patients crossed over electively to the LC group, but only 44% of these underwent LC within the next 3 years. ESWL cost Can $58.9/ day of disability saved. ESWL is limited by its selective applicability and modest stone disappearance rate. Its cost-effectiveness is largely dependent on patient acceptance of recurrent episodes of biliary colic due to the persistence of stone fragments.