Assessment of clinical and economic benefits of weight management with sibutramine in general practice in Germany

The impact of weight loss on health-related quality-of-life: implications for cost-effectiveness analyses

PURPOSE

To assess the impact of weight loss on health-related quality-of-life (HRQL), to describe the factors associated with improvements in HRQL after weight loss, and to assess the relationship between obesity as assessed by body mass index (BMI) and HRQL before and after weight loss.

METHODS

We studied 188 obese patients with BMI ≥ 32 kg/m(2) with one or more comorbidities or ≥35 kg/m(2). All patients had baseline and follow-up assessments of BMI and HRQL using the EuroQol (EQ-5D) and its visual analog scale (VAS) before and after 6 months of medical weight loss that employed very low-calorie diets, physical activity, and intensive behavioral counseling.

RESULTS

At baseline, age was 50 ± 8 years (mean ± SD), BMI was 40. 0 ± 5.0 kg/m(2), EQ-5D-derived health utility score was 0.85 ± 0.13, and VAS-reported quality-of-life was 0.67 ± 0.18. At 6-month follow-up, BMI decreased by 7.0 ± 3.2 kg/m(2), EQ-5D increased by 0.06 [interquartile range (IQR) 0.06-0.17], and VAS increased by 0.14 (IQR 0.04-0.23). In multivariate analyses, improvement in EQ-5D and VAS were associated with lower baseline BMI, greater reduction in BMI at follow-up, fewer baseline comorbidities, and lower baseline HRQL. For any given BMI category, EQ-5D and VAS tended to be higher at follow-up than at baseline.

CONCLUSION

Measured improvements in HRQL between baseline and follow-up were greater than predicted by the reduction in BMI at follow-up. If investigators use cross-sectional data to estimate changes in HRQL as a function of BMI, they will underestimate the improvement in HRQL associated with weight loss and underestimate the cost-utility of interventions for obesity treatment.

A systematic review and critical assessment of health state utilities: weight change and type 2 diabetes mellitus

OBJECTIVE

The study aimed to conduct a systematic literature search to identify health state utilities for weight change in type 2 diabetes mellitus (T2DM) and to review those values for appropriateness for inclusion in a submission to the National Institute for Health and Clinical Excellence (NICE).

METHODS

The search was conducted using keywords and Medical Subject Heading (MeSH) terms designed to exhaustively capture health state utility values across a variety of known economic, health technology assessment and peer-reviewed publication databases. The values were then critically reviewed from the perspective of the NICE reference case (2008 methods guide).

RESULTS

The search resulted in a large number of repeat references across databases suggesting good sensitivity. Thirty-three articles were selected for inclusion and subjected to a critical review including their methodological quality, symmetry with the NICE reference case, sample size and country source. This critical review led to a shortlist of nine utility studies, all of which had potential for inclusion in cost-utility models or a meta-analysis.

CONCLUSIONS

A relatively large number of utilities have been collected in weight change and T2DM. Many of these utility values are not suitable for inclusion in a NICE submission. A better way of reviewing the methodological quality of utilities is needed.

Economic evaluations of adult weight management interventions: a systematic literature review focusing on methods used for determining health impacts

BACKGROUND

One of the challenges when undertaking economic evaluations of weight management interventions is to adequately assess future health impacts. Clinical trials commonly measure impacts using surrogate outcomes, such as reductions in body mass index, and investigators need to decide how these can best be used to predict future health effects. Since obesity is associated with an increased risk of numerous chronic diseases occurring at different future time points, modelling is needed for predictions.

OBJECTIVE

To assess the methods used in economic evaluations to determine health impacts of weight management interventions and to investigate whether differences in methods affect the cost-effectiveness estimates.

METHODS

Eight databases were systematically searched. Included studies were categorized according to a decision analytic approach and effect measures incorporated.

RESULTS

A total of 44 articles were included; 21 evaluated behavioural interventions, 12 evaluated surgical procedures and 11 evaluated pharmacological compounds. Of the 27 papers that estimated future impacts, eleven used Markov modelling, seven used a decision tree, five used a mathematical application, two used patient-level simulation and the modelling method was unclear in two papers. The most common types of effects included were co-morbidity treatment costs, heath-related quality of life due to weight loss and gain in survival. Only 12 of the studies included heath-related quality of life gains due to reduced co-morbidities and only one study included productivity gains. Despite consensus that trial-based analysis on its own is inadequate in guiding resource allocation decisions, it was used in 39% of the studies. Several of the modelling papers used model structures not suitable for chronic diseases with changing health risks. Three studies concluded that the intervention dominated standard care; meaning that it generated more quality-adjusted life-years (QALYs) for less cost. The incremental costs per QALY gained varied from $US235 to $US56,836 in the remaining studies using this outcome measure. An implicit hypothesis of the review was that studies including long-term health effects would illustrate greater cost effectiveness compared with trial-based studies. This hypothesis is partly confirmed with three studies arriving at dominating results, as these reach their conclusion from modelling future co-morbidity treatment cost savings. However, for the remaining studies there is little indication that decision-analytic modelling disparities explain the differences.

CONCLUSIONS

This is the first literature review comparing methods used in economic evaluations of weight management interventions, and it is the first time that observed differences in study results are addressed with a view to methodological explanations. We conclude that many studies have methodological deficiencies and we urge analysts to follow recommended practices and use models capable of depicting long-term health consequences.

Economic evaluation of lifestyle interventions for preventing diabetes and cardiovascular diseases

Lifestyle interventions (i.e., diet and/or physical activity) are effective in delaying or preventing the onset of diabetes and cardiovascular disease. However, policymakers must know the cost-effectiveness of such interventions before implementing them at the large-scale population level. This review discusses various issues (e.g., characteristics, modeling, and long-term effectiveness) in the economic evaluation of lifestyle interventions for the primary and secondary prevention of diabetes and cardiovascular disease. The diverse nature of lifestyle interventions, i.e., type of intervention, means of provision, target groups, setting, and methodology, are the main obstacles to comparing evaluation results. However, most lifestyle interventions are among the intervention options usually regarded as cost-effective. Diabetes prevention programs, such as interventions starting with targeted or universal screening, childhood obesity prevention, and community-based interventions, have reported favorable cost-effectiveness ratios.

Obesity management interventions: a review of the evidence

The burden of disease associated with the obesity epidemic shortens lives, and prevalence is accelerating. As with other chronic diseases, improved outcomes are associated with effective self-management of obesity across the life span. The disease of obesity, then, fits squarely within the disease management and chronic care models. This article reviews selected interventions, described in peer-reviewed literature, designed to achieve significant weight loss for individuals identified as overweight or obese. The study objective is to provide an overview of the full range of methods and models for weight loss, including some available without medical supervision. The intended audience includes individuals and organizations with an expressed interest in disease management and the chronic care models. Our review identified promising lines of investigation for future research that span diverse medical disciplines applied to obesity. The quality of the studies included in our review was uneven, and compromises the current evidence for effectiveness and efficacy. Generally, our results showed that combination approaches-surgical or pharmacologic, combined with a behavioral intervention-were most likely to be effective.

Sample size in obesity trials: patient perspective versus current practice

OBJECTIVE

To evaluate patient opinions on acceptable risks in exchange for a given degree of weight loss and their implications for sample size determination in obesity randomized clinical trials (RCTs).

DESIGN

. Survey of patients entering RCTs for weight loss in a university-based clinical research setting and power calculations based on their responses. Participants. Men (n = 8) and women (n = 66) between 24 and 73 years of age with body mass indices ranging from 26.8 to 40.5 kg/m(2). Measurements. Survey responses to questions assessing the added risk of serious adverse events (SAEs) or death one is willing to assume for a given degree of weight loss.

RESULTS

For 5% and 10% weight loss against risk for death per se, the mean acceptable risk tended to be about 3.5%, but the median (0.00) and mode (0.00) suggested that for most individuals, only a risk of < or = 1% would be acceptable. Figures, estimated dropout rates, and base rates of SAEs (including deaths) from recent obesity trials indicate that 1-year 2-group obesity RCTs would need tens of thousands of participants per group to have 80% power to detect risks that are meaningful to patients at the 2-tailed 0.05 alpha level.

CONCLUSION

Patient education is needed to explain which risks are realistically detectable in RCTs so that patients may provide truly informed consent, or RCT standards should be modified to meet patients' implicit expectations.

Cost-effectiveness of pharmacological anti-obesity treatments: a systematic review

AIM

To review economic evaluations of weight loss drugs and compare reported incremental cost-effectiveness ratios (ICERs).

METHODS

A literature search was conducted for cost-effectiveness (CEAs) and cost-utility analyses (CUAs) of sibutramine, orlistat and rimonabant.

RESULTS

Fourteen unique articles were identified (11 CUAs and 3 CEAs; 9 orlistat, 4 sibutramine and 1 rimonabant). All used diet and exercise as comparator, whereas none included indirect costs. Time horizons varied from treatment period only (1-4 years) to 80 years (median 7.5 years). Longer studies modeled effects on diabetes, micro- and macrovascular complications, coronary heart disease and death. Of the CUAs, the median ICER was 16,000 euro(2007)/QALY (quality-adjusted life-year; range 10,000-88,000), with the worst cost-effectiveness when recommended stop rules for non-responding patients were not applied. All studies but three were funded by the manufacturing company, and the median ICER was considerably higher for independent than for sponsored analyses (62,000 euro vs 15,000 euro/QALY). However, two of the three independent CUAs did not use recommended stop rules, as compared with one of eight manufacturer-sponsored analyses. The results were most sensitive to assumptions regarding weight loss sustainability and utility per kilogram lost. Side effects and dropout because of reasons other than lack of efficacy were generally not incorporated.

CONCLUSION

Published economic evaluations indicate that orlistat, sibutramine and rimonabant are within the range of what is generally regarded as cost-effective. Uncertainty remains about weight loss sustainability, utility gain associated with weight loss and extrapolations from transient weight loss to long-term health benefits. Modeling of head-to-head comparisons and attrition is needed, as are analyses conducted independently of manufacturing companies.

The cost-effectiveness of sibutramine in non-diabetic obese patients: evidence from four Western countries

This paper aims to assess the cost-effectiveness of sibutramine in treating obese patients in the Western countries. The model estimates the costs and quality of life benefits directly associated with weight losses combined with the costs and benefits associated with the reduced incidence of coronary heart disease (CHD) and diabetes. The pivotal effectiveness evidence is derived from a German multicentre, double-blind, randomized clinical trial on obese (body mass index >/= 30 Euro kg m(-2)) patients. The incremental cost per quality-adjusted life year ranges from 10,734 Euro in Switzerland to 13,707 Euro in Germany. The total number of CHD events avoided ranges from 1.96 for the UK to 4.49 for Switzerland. The number of diabetes cases avoided is in the region of 3.0 (ranges from 2.58 for Germany to 3.28 for Switzerland). The majority of costs and benefits are accrued through sibutramine treatment and monitoring. Univariate sensitivity analyses show that results are sensitive to changes in the utility directly attributable to weight losses. The results demonstrate that the benefits associated with sibutramine-induced weight losses are obtained at a reasonable cost in each of the settings explored and suggest that sibutramine treatment could be considered as a viable option for pharmacotherapy treatment alongside diet and exercise.