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PubMed2006

Eradication of Helicobacter pylori for non-ulcer dyspepsia.

BACKGROUND: Helicobacter pylori (H pylori) is the main cause of peptic ulcer disease. The role of H pylori in non-ulcer dyspepsia is less clear. OBJECTIVES: To determine the effect of H pylori eradication on dyspepsia symptoms in patients with non-ulcer dyspepsia. SEARCH STRATEGY: Trials were identified through electronic searches of the Cochrane Controlled Trials Register (CCTR), MEDLINE, EMBASE, CINAHL and SIGLE, using appropriate subject headings and keywords, searching bibliographies of retrieved articles, and through contacts with experts in the fields of dyspepsia and with pharmaceutical companies. SELECTION CRITERIA: All parallel group randomised controlled trials (RCTs) comparing drugs to eradicate H pylori with placebo or other drugs known not to eradicate H pylori for patients with non-ulcer dyspepsia. DATA COLLECTION AND ANALYSIS: Data were collected on individual and global dyspeptic symptom scores, quality of life measures and adverse effects. Dyspepsia outcomes were dichotomised into minimal/resolved versus same/worse symptoms. MAIN RESULTS: Twenty one randomised controlled trials were included in the systematic review. Eighteen trials compared antisecretory dual or triple therapy with placebo antibiotics +/- antisecretory therapy, and evaluated dyspepsia at 3-12 months. Seventeen of these trials gave results as dichotomous outcomes evaluating 3566 patients and there was no significant heterogeneity between the studies. There was a 10% relative risk reduction in the H pylori eradication group (95% CI = 6% to 14%) compared to placebo. The number needed to treat to cure one case of dyspepsia = 14 (95% CI = 10 to 25). A further three trials compared Bismuth based H pylori eradication with an alternative pharmacological agent. These trials were smaller and had a shorter follow-up but suggested H pylori eradication was more effective than either H2 receptor antagonists or sucralfate in treating non-ulcer dyspepsia. AUTHORS' CONCLUSIONS: H pylori eradication therapy has a small but statistically significant effect in H pylori positive non-ulcer dyspepsia. An economic model suggests this modest benefit may still be cost-effective but more research is needed.

Adult↗
PubMed2000

Selective serotonin reuptake inhibitors versus tricyclic and heterocyclic antidepressants: comparison of drug adherence.

BACKGROUND: Selective serotonin reuptake inhibitors are thought to have better discontinuation rates (i.e. less people dropping out) than tricyclic and heterocyclic antidepressant drugs. It is important to quantify the drop-out rates of different antidepressant drugs in order to have a better understanding of the relative tolerability of these drugs. OBJECTIVES: To assess the comparative tolerability of selective serotonin reuptake inhibitors and tricyclic/heterocyclic antidepressant drugs. SEARCH STRATEGY: We searched the Cochrane Collaboration Depression, Anxiety and Neurosis Controlled Trials Registers (1997 to 1999), MEDLINE (1966 to 1999), EMBASE (1974 to 1999) We also searched specialist journals, the reference lists of relevant papers and previous systematic reviews, conference abstracts and government documents. Representatives of the pharmaceutical industry were contacted. SELECTION CRITERIA: Parallel group randomised controlled trials comparing selective serotonin reuptake inhibitors with tricyclic or heterocyclic antidepressants in people with depression. DATA COLLECTION AND ANALYSIS: Two reviewers independently extracted data and a third reviewer checked any cases of disagreement. MAIN RESULTS: We included 136 trials. The selective serotonin reuptake inhibitors showed less participants dropping out compared to the tricyclic/heterocyclic group (odds ratio 1.21, 95% confidence interval 1.12 to 1.30). A statistically significant difference was found in total drop-outs between the selective serotonin reuptake inhibitors and the old tricyclics as well as the newer tricyclics. When the selective serotonin reuptake inhibitors were compared to the heterocyclic antidepressants, there was a non significant difference favouring the selective serotonin reuptake inhibitors. The poor tolerability profile of the old tricyclics was explained by differences in drop-outs for side-effects, but not for inefficacy. REVIEWER'S CONCLUSIONS: Whilst selective serotonin reuptake inhibitors do appear to show an advantage over tricyclic drugs in terms of total drop-outs, this advantage is relatively modest. This has implications for pharmaco-economic models, some of which may have overestimated the difference of drop-out rates between selective serotonin reuptake inhibitors and tricyclic antdepressants. These results are based on short-term randomised controlled trials, and may not generalise into clinical practice.

Antidepressive Agents↗
PubMed1994

Managed mental health care and professional compensation.

Managed care and organized systems of care are restructuring the delivery of care in the United States. As care is reorganized, physician practice styles, autonomy, and compensation are undergoing profound changes. To successfully integrate physicians into the new managed systems of care, their organizational relationship to and their compensation within these systems must be carefully considered. This paper first explores physician motivation as it is related to compensation. The paper then describes a variety of emerging organizational designs aimed at aligning the interests of physicians and hospitals. The author considers fully integrated, physician-hospital organizations with target income compensation arrangements to be most suitable to the collective success of professionals and organized systems of care. The paper concludes with a discussion of the many dilemmas and challenges posed by the intertwining of managed care, organized networks of care, and professional compensation.

Humans↗
PubMedDate not supplied

Solo versus group practice in the medical profession: the influence of malpractice risk.

While Partnerships are a significant form of business organization in many sectors of the economy, relatively little is known about the incentives which lead to their formation. This paper explores the formation of partnerships among office based physicians when facing some risk of malpractice litigation. Theoretical results indicate that malpractice exposure can increase the incentives to shirk within a partnership, and so exert a significant influence on the decision to form a partnership. Empirical results find that malpractice risk has the expected negative effect on some partnership formation.

Appointments and Schedules↗
PubMed2003

Deadweight loss of bacterial resistance due to overtreatment.

Widespread use of antibiotics is considered the major driving force behind the development of antibiotic resistance. The benefits of exceeding the welfare-maximizing level of antibiotic use are below the costs of resistance created by this excess quantity of antibiotics used, thereby resulting in a welfare deadweight loss. This paper uses a simple economic model to examine the theoretical and empirical aspects of the welfare loss generated by resistance and analyzes its policy implications. The annual deadweight loss associated with outpatient prescriptions for amoxicillin in the United States is estimated at US dollars 225 million.

Amoxicillin↗
PubMed2004

Insomnia, biological clock, and the bedtime decision: an economic perspective.

While insomnia can be a symptom of numerous mental and physical illnesses, it is frequently diagnosed as a sleep disorder in its own right, caused mainly by stressful life events or by non-synchronization of individuals' biological sleep-wake cycle with the one they choose to practice. Because of irregular work schedules, late-night entertainment, or rapid crossing of several time zones, individuals might retire to bed earlier or later than their biological bedtime, experiencing difficulties in falling asleep. The present paper develops a simple economic model of the bedtime decision, viewing the individual as a rational decision-maker who determines her insomnia level through consciously weighing the cost and benefit of deviating from her biological bedtime. The model is then used to examine the individual's response to stress, yielding a prediction which is consistent with observed behavior, although not with sleep therapists' recommendations. Finally, the model is applied to the case of transmeridian flights, explaining jet lag as a rational adjustment to a misalignment between the individual's slow-to-adapt internal clock and her external environment.

Biological Clocks↗
PubMed2003

Regression analysis of incomplete medical cost data.

The accumulation of medical cost over time for each subject is an increasing stochastic process defined up to the instant of death. The stochastic structure of this process is complex. In most applications, the process can only be observed at a limited number of time points. Furthermore, the process is subject to right censoring so that it is unobservable after the censoring time. These special features of the medical cost data, especially the presence of death and censoring, pose major challenges in the construction of plausible statistical models and the development of the corresponding inference procedures. In this paper, we propose several classes of regression models which formulate the effects of possibly time-dependent covariates on the marginal mean of cost accumulation in the presence of death or on the conditional means of cost accumulation given specific survival patterns. We then develop estimating equations for these models by combining the approach of generalized estimating equations for longitudinal data with the inverse probability of censoring weighting technique. The resultant estimators are shown to be consistent and asymptotically normal with simple variance estimators. Simulation studies indicate that the proposed inference procedures behave well in practical situations. An application to data taken from a large cancer study reveals that the Medicare enrollees who are diagnosed with less aggressive ovarian cancer tend to accumulate medical cost at lower rates than those with more aggressive disease, but tend to have higher lifetime costs because they live longer.

Aged↗
PubMed2005

Semi-parametric modelling for costs of health care technologies.

Cost data that arise in the evaluation of health care technologies usually exhibit highly skew, heavy-tailed and, possibly, multi-modal distributions. Distribution-free methods for analysing these data, such as the bootstrap, or those based on the asymptotic normality of sample means, may often lead to inefficient or misleading inferences. On the other hand, parametric models that fit the data (or a transformation of the data) equally well can produce very different answers. We consider a Bayesian approach, and model cost data with a distribution composed of a piecewise constant density up to an unknown endpoint, and a generalized Pareto distribution for the remaining tail.

Animals↗
PubMed2006

Power and money in cluster randomized trials: when is it worth measuring a covariate?

The power to detect a treatment effect in cluster randomized trials can be increased by increasing the number of clusters. An alternative is to include covariates into the regression model that relates treatment condition to outcome. In this paper, formulae are derived in order to evaluate both strategies on basis of their costs. It is shown that the strategy that uses covariates is more cost-efficient in detecting a treatment effect when the costs to measure these covariates are small and the correlation between the covariates and outcome is sufficiently large. The minimum required correlation depends on the cluster size, and the costs to recruit a cluster and to measure the covariate, relative to the costs to recruit a person. Measuring a covariate that varies at the person level only is recommended when cluster sizes are small and the costs to recruit and measure a cluster are large. Measuring a cluster level covariate is recommended when cluster sizes are large and the costs to recruit and measure a cluster are small. An illustrative example shows the use of the formulae in a practical setting.

Child↗
PubMedDate not supplied

Estimating the causal effects of smoking.

An important application of statistics in recent years has been to address the causal effects of smoking. There is little doubt that there are health risks associated with smoking. However, more general issues concern the causal effects due to the alleged misconduct of the tobacco industry or due to programmes designed to curtail tobacco use. To address any such causal question, assumptions must be made. Although some of the issues are well known in the statistical and epidemiological literature, there does not appear to be a unified treatment that provides prescriptive guidance on the estimation of these causal effects with explication of the needed assumptions. A 'conduct attributable fraction' is derived, which allows for arbitrary changes in smoking and non-smoking health care expenditure related factors in a counterfactual world without the alleged misconduct, and therefore generalizes the traditional 'smoking attributable fraction'. The formulation presented here, although described for the problem of estimating excess health care expenditures due to the alleged misconduct of the tobacco industry, is more general. It can be applied to any outcome, such as mortality, morbidity, or income from excise taxes, as well as to any situation in which consequences due to alleged misconduct (for example, of two entities, such as the tobacco and the asbestos industries) or due to hypothetical programmes (for example, extra smoking reduction initiatives) are to be estimated.

Delivery of Health Care↗
PubMed2003

Evaluation of the fire simulation processes of the National Fire Management System's Initial Attack Analysis processor.

The fire simulation processes of the National Fire Management System's (NFMAS) Initial Attack Analysis (IAA) processor were evaluated by conducting two types of sensitivity analysis: one based on a hypothetical set of data to assess IAA's outputs under a wide range of fire input values, and the other using an actual Stanislaus National Forest database to test IAA's validity with a real set of data. The results revealed that IAA's outputs (projected annual number of fires and area burned) were most sensitive, in descending order, to the input values of the fire spread rate, the productivity rates of the suppression forces, and the initial attack time, for all fuel models tested. In contrast, IAA's outputs were extremely insensitive to variations in the fire size at discovery. Changes are necessary in the ways IAA incorporates the fire size at discovery to facilitate the comparison among various fire detection options. The program's "escaped fire situation" analysis was found inadequate, because the projected annual frequencies and final sizes of the simulated escaped fire events produced unacceptable results with the Stanislaus National Forest database. Assigning final sizes to simulated escaped fires according to the fire intensity level in which they are historically expected to occur provides a consistent way of calculation of the projected annual area burned and the consequent cost plus net value change (C + NVC).

Conservation of Natural Resources↗
PubMed2003

The resource economics of chemical and structural defenses across nitrogen supply gradients.

In order to better understand the role of nutrient supplies in determining the prevalence of plant defense types, we investigated the theoretical relationships between ecosystem N supply and the net C gain of shoots that were undefended or defended in one of three ways: (1) by N-free chemical compounds, (2) by N-containing chemical compounds, or (3) by structural defenses. By extending economic models of shoot resource balance to include the relative value of C and N, depreciation, and amortization, we were able to show that the relative net C gain of the three defense types were similar to changes in their generally understood abundance along an N supply gradient. At low N supply, the additional C acquired when investing C in defense is much higher than investing N in defenses. Only at high N supply is it better to invest large quantities of N in defense rather than additional photosynthesis. In a sensitivity analysis, net C gain of shoots was most sensitive to factors that affect the relative value of C and N and the rate of herbivory. Although there is support for the relative value of C and N influencing defense strategies, more research is necessary to understand why tannins are not more prevalent at high N supply and why moderate amounts of N-based defenses are not used at low N supply.

Adaptation, Physiological↗
PubMed2003

Economic evaluation of antiaromatase agents in the second-line treatment of metastatic breast cancer.

GOALS OF WORK: An economic evaluation was conducted comparing anastrozole, exemestane, letrozole and megestrol for the second-line treatment of postmenopausal patients with hormone-sensitive metastatic breast cancer who had failed tamoxifen. METHODS: An economic model was developed based on data from phase III megestrol-controlled clinical trials of antiaromatase agents (AA) and estimates of resource utilization from both Statistic Canada's Population Health Model for breast cancer and expert opinion. MAIN RESULTS: In megestrol-controlled trials, anastrozole and exemestane equivalently improved survival compared to megestrol, while letrozole did not. Compared to megestrol, exemestane and anastrozole both cost Canadian $9000 per life-year gained, and letrozole saved Canadian $300 annually, with no life-year gain. Cost-effectiveness results were robust under sensitivity analysis testing. However, the model was dependent on any difference between AAs with respect to survival benefit and drug acquisition price. CONCLUSION: Based on available data and this cost-effectiveness analysis, exemestane and anastrozole are appropriate choices for second-line hormonal treatment of metastatic breast cancer.

Aged↗
PubMed2006

Anastrozole is cost-effective vs tamoxifen as initial adjuvant therapy in early breast cancer: Canadian perspectives on the ATAC completed-treatment analysis.

GOALS OF WORK: To conduct an economic analysis comparing tamoxifen and anastrozole (Arimidex) in the adjuvant treatment of hormone receptor-positive (HR+), post-menopausal early breast cancer patients. MATERIALS AND METHODS: An economic model examined typical patients (64 years of age, HR+, 64% node negative) from the Arimidex, tamoxifen alone, or in combination (ATAC) trial over a lifetime horizon. Rates of events were derived from ATAC trial results. Post-trial event rates were drawn from the literature for tamoxifen; event rates for anastrozole were modified by the relative risks observed in the ATAC trial. Resource utilization was drawn from Statistics Canada's Population Health Model for breast cancer, supplemented by an expert panel. A public health care system perspective, 2004 Canadian prices and a 5% discount rate were employed. RESULTS: Anastrozole-taking patients incurred additional hormonal treatment costs compared to tamoxifen-taking patients (incremental lifetime cost, 6,974 Canadian dollars per patient), partially offset by reduced downstream recurrences of breast cancer (1,143 Canadian dollars lifetime savings per patient) for a net incremental cost of 5,796 Canadian dollars per patient on anastrozole. The anastrozole-treated patients were projected to experience a 5.6% absolute risk reduction of first breast cancer recurrence and a 2.8% absolute risk reduction in breast cancer death. This corresponded to 30,000 Canadian dollars per life year gained and 28,000 Canadian dollars per quality-adjusted life year gained (95% confidence interval, 17,428 to 54,605 Canadian dollars). The results were affected by the duration and extent of anastrozole benefit under sensitivity analysis but remained cost-effective. CONCLUSION: Compared to tamoxifen, anastrozole therapy is effective and cost-effective as initial adjuvant therapy in post-menopausal, HR+ early breast cancer patients.

Analysis of Variance↗
PubMed2005

Cost-effectiveness of thrombolytics: a simplified model.

OBJECTIVE OF THE STUDY: To construct a simple model for an internal, retrospective cost-effectiveness analysis and to calculate the incremental cost-effectiveness of tissue plasminogen activator (TPA) over streptokinase (SK) in Turkey. SETTING: Koşuyolu Heart, Education and Research Hospital, Istanbul, Turkey. METHOD: Among patients who were hospitalized for treatment of acute myocardial infarction (AMI), 196 were randomly selected. One-year mortality rates according to the treatment groups (TPA, SK, other) were determined. Among surviving patients, 28 from TPA and another 28 from SK group were randomly selected for the pharmacoeconomic analysis. Patient treatment data were taken from medical records while data regarding to costs were taken from hospital bills. MAIN OUTCOME MEASURES: Incremental cost-effectiveness ratio (ICER). The cost part of the ratio was considered as 'the overall-costs', while the effectiveness part was considered as 'lives saved' per treatment group. RESULTS: With an increased one-year survival rate of 2.37% and an increased cost of euro 1120.8 ($1165.6) per patient in the TPA group, the ICER for the use of TPA instead of SK was euro 47,289 ($49,180.6) per life saved. CONCLUSION: This model can be a guide for similar analyses. The results of our study (the incremental cost-effectiveness of TPA over SK) will be informative for the decision-makers in Turkey, by whom the medical benefit for money spent would be assessed and judged. We believe that our results make a contribution to similar studies in the literature.

Cost-Benefit Analysis↗
PubMed1986

Seat belt usage rates: a test of Peltzman's hypothesis.

Despite the universally accepted belief that the use of seat belts would have a significant impact upon the number of vehicular fatalities, current evidence indicates that relatively few drivers employ their seat belts. Various hypotheses have been offered to explain this phenomenon, many of which conclude that a driver's decision to use a seat belt is independent of the risk experienced in his trip making. This paper develops an economic model which focuses upon the relationship between driver use of seat belts and the travel conditions under which trips are made. Using data obtained from a national survey of households, a binary logit model is developed to test the hypothesis that seat belt usage is influenced by the level of risk experienced in one's trip making. The estimation results were consistent with the underlying hypothesis that individuals travelling in more risky environments are more likely to use their seat belts. The econometric results are then employed to examine various policy issues, including the predicted use of seat belts for population sub-groups, driver response to the introduction of a small urban car, and the impact upon the probability of a fatality resulting from vehicle fleet downsizing.

Accidents, Traffic↗