The cost-effectiveness of metformin in the US diabetes prevention program trial: Simple interpretations need not apply

Based on previously published US Diabetes Prevention Program (DPP) cost-effectiveness analyses (CEAs) metformin continues to be promoted as "cost-effective." We review the DPP within-trial CEA to assess this claim. Treatment alternatives included placebo (plus standard lifestyle advice), branded metformin and individual lifestyle modification. We added generic metformin as an alternative. Original published CEA data were taken as given and re-analyzed according to accepted principles for calculating incremental cost-effectiveness ratios (ICERs) in the economic evaluation field. With more than two treatments as in the DPP, these require attention to the rankings of interventions according to cost or effect prior to stipulating appropriate ICERs to calculate. With proper ICERs neither branded nor generic metformin was cost-effective, regardless of the value assumed for the willingness to pay for the quality-adjusted life year outcome assessed. Metformin alternatives were technically inefficient compared to placebo or the lifestyle modification alternative. Net loss calculations indicated substantial costs/health losses to using metformin instead of the optimal lifestyle alternative in response to metformin having been inaccurately labelled "cost-effective" in the original CEA. That CEA and subsequent analyses and citations of such analyses continue to claim that both metformin and lifestyle modification are cost-effective in diabetes prevention based on DPP data. Using metformin implies substantial costs and health losses compared to the cost-effective lifestyle modification. It may be that metformin has a role in cost-effective diabetes prevention, but this has yet to be shown based on DPP data.

An economic evaluation of a European cohort from a multinational trial of linezolid versus teicoplanin in serious Gram-positive bacterial infections: the importance of treatment setting in evaluating treatment effects

In a recent multinational trial, hospital resource use and total cost of treatment were compared between linezolid and teicoplanin for severe Gram-positive bacterial infections among 227 European hospitalised patients. The results show that the linezolid group had a 3.2-day (6.3 for linezolid versus 9.5 for teicoplanin groups) shorter mean intravenous antibiotic treatment duration. Certain baseline variables, particularly the inpatient location at enrolment and the presence of outpatient/home parenteral antibiotic therapy (OHPAT), had substantial effects on length of stay (LOS) and cost of treatment. After adjusting for the between-treatment difference in these two variables and other baseline variables, the results showed non-significant shorter LOS and lower mean total cost of treatment for the linezolid group among patients with no access to OHPAT.

Comparison of linezolid with oxacillin or vancomycin in the empiric treatment of cellulitis in US hospitals

In this decision-model analysis, the authors compared overall clinical efficacy and total cost of empiric treatment of hospitalized cellulitis patients prescribed linezolid and oxacillin or vancomycin. The authors hypothesized that, when used appropriately, empiric linezolid treatment is an effective, potentially cost-saving antibiotic compared with treatment initiated with oxacillin or vancomycin. Data on efficacy, duration of antibiotic treatment, and hospital stay for first-line treatment success were obtained from two clinical trials. Other medical resource use data were obtained from an expert panel of clinicians. US hospital direct medical costs were determined using standard costing techniques. Overall efficacy and total cost of treatment were estimated for combinations of the risk of being infected with methicillin-resistant pathogens. Sensitivity analyses were performed to test the impact of changes in major assumptions. Overall first-line efficacy is better for empiric treatment initiated with linezolid than with oxacillin or vancomycin across the spectrum of the risk of being infected with methicillin-resistant bacteria. The average total cost of treatment is lower for treatment initiated with linezolid than with vancomycin across the spectrum, or than with oxacillin when the risk of being infected with methicillin-resistant pathogens is 18.7 % or higher. Linezolid appears to be at least as effective as vancomycin or oxacillin for empiric treatment of hospitalized cellulitis patients. Linezolid is likely to be less costly compared with vancomycin at all resistance rates and with oxacillin when the risk of infection with methicillin-resistant pathogens is greater than 18.7 %, a resistance rate commonly seen in US hospitals.

Effect of linezolid versus vancomycin on length of hospital stay in patients with complicated skin and soft tissue infections caused by known or suspected methicillin-resistant staphylococci: results from a randomized clinical trial

BACKGROUND

Complicated skin and soft tissue infections are common surgical indications usually requiring patients to be hospitalized, and are often caused by gram-positive bacteria, including methicillin-resistant staphylococci such as MRSA. Vancomycin has been the standard treatment for methicillin-resistant staphylococcal infections in many countries, but its intravenous-only formulation for systemic infections often confines patients to the hospital for the treatment. Linezolid, a novel oxazolidinone antibiotic available in intravenous and 100% bioavailable oral forms, was shown in a randomized trial to be as efficacious as vancomycin for suspected or proven methicillin-resistant staphylococcal infections. To determine if oral linezolid can reduce length of hospital stay (LOS) when compared to vancomycin, we compared the LOS for the 230 complicated skin and soft tissue infection patients enrolled in this trial.

MATERIALS AND METHODS

Patients received up to four weeks of linezolid (intravenous followed by optional oral) or vancomycin (intravenous only), followed by up to four weeks of observation. Unadjusted LOS was estimated using Kaplan-Meier survival functions, whereas the log-logistic survival analysis model was used to estimate the multivariate-adjusted LOS controlling for patient demographics and selected baseline clinical variables. Analysis was done on the intent-to-treat (n = 230) sample as well as on two subsamples of the clinically evaluable (n = 144) and surgical site infection (n = 114) patients.

RESULTS

The unadjusted Kaplan-Meier median LOS was five days shorter for the linezolid group than the vancomycin group in the intent-to-treat sample (9 vs. 14 days, p = 0.052). It was eight days shorter (8 vs. 16 days, p = 0.0025) in the clinically evaluable sample, but the difference in the surgical site infection sample was not significant (10 vs. 14 days; p = 0.29). The linezolid group's unadjusted mean LOS was 1.7, 5.3 and 0.8 days shorter in the intentto-treat, clinically evaluable, and surgical site infection samples, respectively. After adjusting for age, gender, race, geographic region, bacteremia, type of inpatient location, and number of concurrent medical conditions using the log-logistic model, between-treatment differences in the multivariate-adjusted median LOS decreased to 3, 6, and 3 days, whereas the differences in mean LOS increased to 3.1, 6.5 and 2.5 days for the intent-to-treat, clinically evaluable, and surgical site infection samples (p < 0.01, < 0.01, and < 0.10), respectively. When the between-treatment differences in LOS were expressed as odds ratio of hospital discharges, multivariate-adjustment increased the odds ratios in favor of linezolid for all the three samples.

CONCLUSION

Results from this randomized trial show that linezolid can significantly reduce LOS for patients with complicated skin and soft tissue infections from suspected or confirmed methicillin-resistant staphylococci.

Hospital resource use and cost of treatment with linezolid versus teicoplanin for treatment of serious gram-positive bacterial infections among hospitalized patients from South America and Mexico: results from a multicenter trial

BACKGROUND

Linezolid is a novel oxazolidinone antibiotic that is effective for the treatment of gram-positive bacterial infections. The oral formulation has the potential to reduce length of stay (LOS) when used as a substitute for parenteral glycopeptide antibiotics. In a recent multinational trial comparing linezolid (i.v. followed by oral administration) with teicoplanin (i.v. alone or switched to i.m. administration), linezolid was found to have better efficacy (P = 0.005) and similar safety for treating serious gram-positive infections.

OBJECTIVE

The purpose of this study was to compare hospital resource use (primarily LOS) and cost of treatment between linezolid and teicoplanin for hospitalized patients with serious gram-positive infections in South America and Mexico using data from the multinational trial.

METHODS

In a multinational, Phase IIIb, open-label, comparator-controlled trial, data were collected from hospitalized patients in centers in 6 South America can countries and Mexico with suspected or confirmed serious gram-positive infections. Patients were randomly assigned to receive i.v. linezolid 600 mg BID (for the entire treatment period [7-28 days] or switched to oral linezolid 600 mg BID) or i.v. teicoplanin (for the entire treatment period or switched to i.m. teicoplanin) dosed per approved prescription information. Data on direct medical resource utilization were collected for each patient, including duration and doses of study medication, location of hospitalization and LOS, comedications, tests and procedures, and outpatient service usage. Unit costs for the medical resources were obtained from secondary sources.

RESULTS

A total of 203 patients (97 treated with linezolid and 106 treated with teicoplanin) were enrolled from these 7 countries. The unadjusted results showed that compared with teicoplanin, patients treated with linezolid had a 3.1-day shorter mean i.v. antibiotic treatment duration (P < 0.001), a 2.0- to 2.2-day shorter median and mean LOS (P = 0.03), and a 311 US dollars lower mean total cost of treatment (P = NS). After controlling for age, race, sex, site of infection, inpatient location when the antibiotic treatment started, number of historical and current comorbidities, and whether the patient had a diagnosis of systemic inflammatory response syndrome or sepsis, the multivariate adjusted results were similar to the unadjusted results. The linezolid group had a 1.6-day shorter adjusted LOS or 66% greater odds of early discharge (P = 0.049) and a 335 US dollars lower adjusted mean total cost of treatment (P = NS).

CONCLUSION

Linezolid was associated with shorter LOS and duration of IV antibiotic treatment than teicoplanin for serious gram-positive infections in the population studied. Linezolid therapy has the potential to reduce the total cost of treatment.

Effects of linezolid on hospital length of stay compared with vancomycin in treatment of methicillin-resistant Staphylococcus infections. An application of multivariate survival analysis

OBJECTIVES

This study was designed to estimate the effects of treatment with linezolid as compared with vancomycin, on the distribution of length of stay (LOS) for hospitalized patients with methicillin-resistant staphylococcal infections. Treatment with intravenous-oral linezolid may allow some patients to be discharged earlier than would treatment with intravenous vancomycin.

METHODS

The analysis is based on the intention-to-treat sample from a randomized multinational phase 3 clinical trial of 460 patients showing that the treatments had equal efficacy. Given the nature of the LOS data, some censoring, and some imbalances between treatment groups, multivariate survival analysis was indicated. Cox proportional hazards assumptions were tested and failed, and accelerated failure time models were tested for best fit. The log-logistic model was selected and used as the basis for estimating the overall treatment effect on LOS. Two methods for multivariate corrections to the survivorship functions allowed more thorough description of the treatment effect on the distribution of LOS, including multivariate-adjusted Kaplan-Meier curves.

RESULTS

The average reduction in LOS associated with linezolid treatment, based on the log-logistic model after correction for covariate effects, was 18.1% (p = .041) or 2.53 days at the median. This was consistent with differences at the medians of the adjusted survivorship functions, which were 2 or 3 days depending on the method used. Treatment-based differences exist at each decile of LOS and consistently favor linezolid. Estimated mean reduction in LOS due to linezolid was 1.62 days in both methods.

CONCLUSIONS

In this study sample, linezolid treatment resulted in statistically significantly shorter hospital LOS as compared with vancomycin treatment. Appropriate use of multivariate survival analysis allows better examination of the nature of the treatment effect on LOS, which may be important for economic analysis.

Approaches to analysis of length of hospital stay related to antibiotic therapy in a randomized clinical trial: linezolid versus vancomycin for treatment of known or suspected methicillin-resistant Staphylococcus species infections

As length of hospital stay (LOS) represents about 70-90% of the total cost of treating serious infections, it represents a key variable in analyzing the health economic differences between treatments for hospitalized patients. In a retrospective analysis using LOS data from a multinational, randomized, phase III clinical trial, we examined two methods (the log-logistic model and Kaplan-Meier survival function) and three approaches (unadjusted total LOS, total LOS adjusted for nontreatment factors, and adjusted LOS based on antibiotic treatment [the antibiotic treatment LOS]) for estimating antibiotic treatment effect on LOS and determined if these approaches could reduce the variation in LOS and control for the imbalance between treatment groups. The trial enrolled patients who were hospitalized with known or suspected Staphylococcus species infections who received at least one dose of linezolid or vancomycin (intent-to-treat sample) and who continued taking the study drug for at least 7 days (clinically evaluable sample). In the intent-to-treat sample, the linezolid group had a 2- (unadjusted) or 4-day (adjusted for nontreatment factors) shorter LOS at the 25th percentile; a 1- or 2-day advantage, respectively, at the 50th percentile (median); and a 0.6- or 1.6-day mean LOS advantage, compared with the vancomycin group. With the antibiotic treatment LOS approach, the linezolid group had mean and median LOS reductions comparable to or greater than those seen in the nontreatment-factor-adjusted results. Results for the clinically evaluable sample were similar to those of the intent-to-treat sample, but the differences between the treatment groups were greater. Linezolid-treated patients had significant LOS reductions that otherwise would be masked without the use of more appropriate, but less commonly used, methods.

Comparison of length of hospital stay for patients with known or suspected methicillin-resistant Staphylococcus species infections treated with linezolid or vancomycin: a randomized, multicenter trial

STUDY OBJECTIVE

To compare hospital length of stay (LOS), weekly discharges, and days of antibiotic treatment with linezolid (intravenous with oral follow-up) and vancomycin (intravenous only).

DESIGN

Multinational, randomized, phase III trial.

SETTINGS

Hospitals in North America, Latin America, and Europe.

PATIENTS

Four hundred sixty hospitalized patients with infections of known or suspected methicillin-resistant Staphylococcus species.

INTERVENTION

Administration of linezolid or vancomycin.

MEASUREMENTS AND MAIN RESULTS

For linezolid recipients, median LOS was 5 and 8 days shorter (p=0.05 and 0.003) in the complicated skin and soft tissue infection intent-to-treat (230 patients) and clinically evaluable (144) samples, and slightly but not significantly shorter in the overall intent-to-treat (460) and clinically evaluable (254) samples. In all samples, linezolid recipients had more discharges in the first week of treatment and fewer days of intravenous therapy than vancomycin recipients.

CONCLUSION

Our results support linezolid's ability to reduce medical resource use.

An economic evaluation of pain therapy after hysterectomy. Patient-controlled analgesia versus regular intramuscular opioid therapy

OBJECTIVES

To assess the economics of patient-controlled analgesia (PCA) treatment versus regular intramuscular (i.m.) injections of opioid analgesia for pain management after hysterectomy.

METHODS

Cost-minimization analysis was used based on the comparable pain control results achieved in the two treatment groups. Observations were taken of treatment-related events with personnel (mostly nursing) time implications during the trial. Times were then associated with these events in an independent study of personnel activity. Costs were linked by using average wage rates for the various personnel for the Montreal area during the time of the study. Drug and material costs were hospital acquisition costs for all items. The cost of the PCA pump itself was not included in the analysis. Several analyses were performed to test the sensitivity of the results to various assumptions.

RESULTS

The results for total costs of the two therapies generally showed PCA to be more costly than regular i.m. injections despite no costs of the pump being included in the analyses. These results were robust with respect to changes in assumptions. Even when intentionally biasing the analysis against i.m. therapy, it was difficult to obtain results that favored PCA.

CONCLUSIONS

Based upon the institutions and assumptions in this analysis, PCA offers no cost advantages over regular i.m. therapy in the pain management after hysterectomy. Regular i.m. injections provided less costly analgesia.

An economic evaluation of levofloxacin versus cefuroxime axetil in the outpatient treatment of adults with community-acquired pneumonia

OBJECTIVE

To examine treatment costs of community-acquired pneumonia (CAP) in adult outpatients given oral (p.o.) levofloxacin or cefuroxime axetil as initial therapy.

STUDY DESIGN

Patients with a primary diagnosis of CAP were enrolled in a multicenter, prospective, randomized, open-label, active-controlled Phase III clinical trial. Both inpatients and outpatients were assigned to 1 of 2 treatment groups: (1) intravenous (i.v.) or p.o. levofloxacin; or (2) i.v. ceftriaxone and/or p.o. cefuroxime axetil.

METHODS

To make legitimate and meaningful cost comparisons between similar types of patients receiving drugs via the same route of administration (i.e., orally), this outpatient economic study examined the resource utilization of the 211 patients enrolled as outpatients who received oral formulations as initial treatment (levofloxacin, 103 patients; cefuroxime axetil, 108 patients). Resource utilization data and clinical trial data were collected concurrently. To generate cost estimates, Medicare cost estimates for resources were multiplied by the resource units used by patients in each treatment arm.

RESULTS

Cost estimates indicated a total cost difference that favored the levofloxacin group (base case: $169; sensitivity analysis: $223 [P = .008]). The results for the base case were not significant (P = .094). In addition, within the cost categories, there was a statistically significant study drug cost differential favoring levofloxacin ($86; P = .0001 for both the base case and sensitivity analysis).

CONCLUSION

Oral levofloxacin is less costly than oral cefuroxime axetil in the outpatient treatment of adults with CAP.

At what price significance? The effect of price estimates on statistical inference in economic evaluation

Because data on resource utilization are now collected in many comparative trials of health interventions, statistical analysis of between-group differences in mean costs has become common. Statistical analyses of costs are generally performed conditional on a set of resource prices (or unit costs), thereby suppressing any uncertainty associated with those price estimates. Results presented here demonstrate that varying price estimates can have a non-negligible effect on statistical inference regarding between-group cost differences. Depending on the relative prices used in an analysis, between-group differences in total costs per patient may be either statistically significant or insignificant, regardless of whether differences in utilization of the underlying resources are statistically significant. These results highlight the importance of recognizing that evaluations based on patient-level economic data may be sensitive to assumptions regarding the values of unobserved variables, such as the relative prices of resources. Traditional methods of sensitivity analysis remain a valuable tool for analysing the implications of uncertainty around estimates of those unobserved variables.

Efficacy and costs of patient-controlled analgesia versus regularly administered intramuscular opioid therapy

BACKGROUND

Many studies have shown the efficacy of patient-controlled analgesia (PCA). However, it is not clear whether PCA has clinical or economic benefits in addition to efficient analgesia. The current study was designed to evaluate these issues by comparing PCA with regularly administered intramuscular injections of opioids after hysterectomy.

METHODS

This prospective study included 126 patients who underwent abdominal hysterectomy and were randomly assigned to receive PCA or regularly timed intramuscular injections of morphine during a period of 48 h. Doses were adjusted to provide satisfactory analgesia in both treatment groups. Pain at rest and with movement, functional recovery, drug side effects, and patient satisfaction were measured using rating scales and questionnaires. The costs of PCA and intramuscular therapy were calculated based on personnel time and drug and material requirements.

RESULTS

Comparable analgesia was observed with the two treatment methods, with no significant differences in the incidence of side effects or patient satisfaction. The medication dosage had to be adjusted significantly more frequently in the intramuscular group than in the PCA patients. The PCA did not favor a faster recuperation time compared with intramuscular therapy in terms of times to ambulation, resumption of liquid and solid diet, passage of bowel gas, or hospital discharge. The results of the economic evaluation, which used a cost-minimization model and sensitivity analyses, showed that PCA was more costly than regular intramuscular injections despite the fact that no costs for the pump were included in the analyses. Cost differences in nursing time favoring PCA were offset by drug and material costs associated with this type of treatment.

CONCLUSIONS

Compared with regularly scheduled intramuscular dosing, PCA is more costly and does not have clinical advantages for pain management after hysterectomy. Because of the comparable outcomes, the general use of PCA in similar patients should be questioned.

Exorcising protocol-induced spirits: making the clinical trial relevant for economics

Economic evaluation frequently depends on estimates from clinical trials of both effectiveness of treatment and resource utilization accompanying it. Protocol-driven events in the trial among other influences often imply that both estimates will be inaccurate. This paper indicates how one may supplement a trial with additional data to connect the artificial trial to the real world of clinical practice. It also shows that data required for this model may be estimated from other sources (via Bayesian modeling) if they are not directly available. The required data include (for example) the proportion of patients with disease who would have presented with clinical signs if they had not been part of a trial that allowed early detection and treatment based on subclinical testing mandated by trial protocol. Those presenting with clinical signs would use additional resources for treatment and/or confirmatory diagnostics. Those with subclinical disease either 1) would never use resources in the case where they never developed clinical manifestations or 2) would use resources of a different type or intensity and perhaps have different outcomes by virtue of their disease's being discovered at a later point in time. Basing resource use and ultimate effectiveness on this revised measure of outcome rather than the one in the trial should lead to more accurate predictions for economic purposes.

Healthy years equivalents versus time trade-off. Ambiguity on certainty and uncertainty

Preference assessment literature has debated the equivalence of the healthy years equivalents (HYE) and time trade-off (TTO) methods. The central issue is whether the HYE measures preferences under uncertainty. This work shows that the two stages of the HYE first add and then remove the element of uncertainty so that ultimately the technique doses not measure preferences under uncertainty. This makes the HYE, at best, a cumbersome equivalent of the TTO.

A novel compliance assessment technique. The randomized response interview

Changing compliance with medication directives can greatly affect health outcomes. To assess programs that influence compliance, accurate measurement of compliance is essential. All currently available methods are imperfect. This paper suggests a new method-the "randomized response interview"-along with a strategy for its implementation.

Respondent-specific information from the randomized response interview: compliance assessment

In situations in which researchers ask potentially embarrassing questions, respondents may feel uncomfortable with revealing certain behavior. Consequently, response rates or accuracy may be low. The "randomized response interview" (RRI) was developed to enable researchers to better elicit responses to such questions. The technique has clear potential in estimating population proportions engaging in embarrassing behavior. It does not appear to have been recognized that one may also obtain more respondent-specific information from the application of the RRI. This article indicates that while still only probabilistic, respondent-specific information is obtainable from the RRI.

The relevance of searching for effects under a clinical-trial lamppost: a key issue

In economic evaluations of new medical technologies, analysts often need to use data from randomized controlled trials. Trials are designed to achieve high internal validity; however, their selected populations and often highly artificial environments may imply low external validity. Thus, the use of trial data in an economic evaluation may bias the results, since economic evaluation is concerned not with theoretical capability in a trial but with likely performance in the practice environment. This paper indicates both the probable bias of one aspect of artificiality in the trial environment--selected populations--and a method of adjusting the analysis so that results will be more likely to reflect actual practice. The judicious use of extra-trial information can be used to correct the biases of clinical trials.

Potential inconsistencies between cost-effectiveness and cost-utility analyses. An upstairs/downstairs socioeconomic distinction

This paper indicates that certain economic evaluation methods (cost-effectiveness and cost-utility analyses) may yield inconsistent results. Along with the lack of formal grounding of these methods in economic "first principles," this finding suggests the possible benefit of greater reliance on the more formally developed method of cost-benefit analysis.

Economic incentives and disincentives for efficient prescribing

Efficient prescribing is a controversial concept when defined in economic terms. Such terms imply that neither the best nor the cheapest drug may be efficient. Efficiency depends on patient evaluations of outcomes--an essential, yet still underdeveloped, field of inquiry. Encouraging prescribing efficiency (once it is clear what efficient treatments are) may require the use of incentives, (economic and otherwise). Although physicians do react to economic incentives, encouraging them to also act as good economists rather than only as good healthcare providers may be difficult since economic efficiency goals may conflict with pure medical goals. While it is conceptually reasonable to assume that economic incentives will accomplish behavioural change, other (noneconomic) incentive mechanisms may appear less controversial. Since it is the result, not the process, that is important, a mix of incentives to achieve efficient solutions is suggested. However, further investigation into both health and economic outcomes research and debate on proper efficiency goals should precede the discussion of optimal incentives.

Community pharmacists as immunization advocates. Cost-effectiveness of a cue to influenza vaccination

To assess the cost-effectiveness of a cue to influenza vaccination provided by community pharmacists, a decision tree was constructed of the consequences of implementing a pharmacy-based vaccine-advocacy program, based on experience gained in an experiment involving three community pharmacies in Durham County, North Carolina. The model used morbidity and mortality assumptions derived from the infectious-disease literature and cost assumptions based on 1990-91 Medicare Part A and Part B reimbursement costs. This analysis suggests that if Medicare reimbursed pharmacists for advising 100,000 patients at risk to accept influenza vaccine through vaccine-advocacy messages, for an apparent expenditure of $110,000, the increased rate of influenza vaccinations would avert 139 hospitalizations and 63 deaths, and actually yield Medicare a net savings of $280,588. These calculations probably underestimate the benefit to society of a pharmacy-based vaccine-advocacy program, because only direct costs to the single government agency were computed and no cost was attributed to death or lost earnings.