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Should patients receive secondary prevention medications for free after a myocardial infarction? An economic analysis |
Choudhry N K, Avorn J, Antman E M, Schneeweiss S, Shrank W H |
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Record Status This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn. Health technology The policy assessed was for insurers not to charge co-payments for combination pharmacotherapy in the secondary prevention of coronary heart disease (CHD)-related events. Combination pharmacotherapy consisted of aspirin (81 mg daily), a beta-blocker (metoprolol, 50mg twice daily), an angiotensin-converting enzyme inhibitor (enalapril, 20 mg twice daily) and a statin (lovastatin, 40 mg daily). The comparator was the existing practice of charging 32% co-payments to the patients.
Economic study type Cost-effectiveness analysis.
Study population The model examined a hypothetical cohort of patients aged 65 years and older who had some drug coverage from an insurer, and who had been discharged after hospitalisation for an MI.
Setting The setting was outpatient care. The economic study was carried out in the USA.
Dates to which data relate The effectiveness evidence was drawn from studies published and databases accessed between 1999 and 2006. Resource use and costs were drawn from studies published, databases accessed, and personal communication with experts between 2004 and 2006. The price years were not reported.
Source of effectiveness data Post-MI event rates included reinfarction, nonfatal stroke, readmission for congestive heart failure (CHF) and death. An estimate of the treatment effect of combination pharmacotherapy was necessary. Medication adherence under standard coverage and the impact on adherence of providing full coverage were inputs to the model.
Modelling The economic model used clinical data and expected therapy adherence to estimate the expected rates of secondary CHD-related events if no secondary prevention was given, and if full coverage was given. The costs associated with each strategy were compared. The time horizon of the analysis was 3 years.
Sources searched to identify primary studies The event rates were measured from Medicare claims data. The authors estimated the treatment effect of combination therapy from the literature; the studies were generally not randomised controlled trials. Adherence was estimated from a World Health Organization study of patient adherence with long-term therapies; change in adherence was estimated from the literature.
Methods used to judge relevance and validity, and for extracting data The authors did not report, or appear to have conducted, a systematic review of the literature to obtain their clinical data. In many cases, the authors applied additional assumptions and calculations to the data they extracted from primary sources. Such assumptions and calculations were described in the endnotes of the text.
Measure of benefits used in the economic analysis The authors did not derive a single measure of benefit but reported expected reductions in CHD-related event rates over 3 years. Specifically, death (due to MI, stroke and CHF), nonfatal MI reinfarction, nonfatal stroke and readmissions for CHF. In effect, a cost-consequences analysis was performed. The authors also calculated the net savings (see 'Direct Costs' and 'Cost Results').
Direct costs Direct costs to the health insurer were included in the analysis. These were medication costs (prices from a major online pharmacy) and the costs of care attributable to post-MI events including inpatient, outpatient, physician, home health and skilled nursing facilities (extracted from the literature; reported only as single event costs). The model ignored the costs of death, reinfarction, stroke or CHF that did not result in hospitalisation, and assumed that fatal and nonfatal CHF were equally costly. Patients were assumed to pay 32% of medication costs under standard coverage. Discounting was relevant to the timeframe of the analysis but was not conducted. The price year for medications appears to have been 2006, but was not apparent for the other costs. The costs were not adjusted for inflation. The costs and the quantities were not reported separately. The authors calculated the budgetary impact of eliminating cost sharing for the target population in the USA.
Statistical analysis of costs The data were deterministic.
Indirect Costs Productivity costs were not relevant to the perspective taken.
Sensitivity analysis One- and two-way sensitivity analyses and a "conservative-case" scenario were examined. The authors also investigated the impact of replacing or adding medications to the base-case combination pharmacotherapy regimen with agents thought to have higher efficacy or higher adherence (e.g. because of reduced frequency of dosing), but higher costs. The main rationale for the inputs and ranges chosen was author opinion.
Estimated benefits used in the economic analysis The average 3-year event rates were:
for fatal MI, 3.1% for current coverage and 2.1% for full coverage;
for fatal stroke, 0.3% for current coverage and 0.2% for full coverage;
for fatal CHF, 0.2% for current coverage and 0.1% for full coverage;
for nonfatal MI, 33.4% for current coverage and 20.3% for full coverage;
for nonfatal stroke, 4% for current coverage and 2.8% for full coverage; and
for nonfatal CHF readmission, 31.8% for current coverage and 25.2% for full coverage.
Cost results The total cost per patient was $22,428 over 3 years under standard coverage and $16,808 over 3 years under full coverage. The net savings reported in the paper were not consistent with these values.
The findings were robust under all sensitivity analyses. Under conservative case assumptions, the savings were $1,181 per patient. The authors stated that eliminating cost-sharing for the 423,000 US patients with drug insurance who will experience their first MI in 2006 would save 4,736 lives and save insurers $2.5 billion.
Synthesis of costs and benefits Since full coverage was the dominant strategy, the costs and benefits were not combined.
Authors' conclusions The elimination of co-payments for post-myocardial infarction (MI) combination pharmacotherapy among insured patients has the potential to simultaneously save lives and reduce medical costs.
CRD COMMENTARY - Selection of comparators The comparator of requiring patients to pay co-payments for combination pharmacotherapy was the current practice for insurers. The issue of co-payments is only relevant to health care systems with insurers. You should decide if this represents a valid comparator in your own setting.
Validity of estimate of measure of effectiveness The parameters were mainly derived from published research of varying quality, but also from online databases and personal communications. The authors did not report any search methods or inclusion criteria, and nor did they provide justification for their selection of the estimates. It was unclear whether the methods used to synthesise the evidence and to estimate the effectiveness of combination therapy were appropriate as they were not described in full. Most of the details of the clinical effectiveness data were contained in the endnotes. The authors acknowledged the uncertainty around the true impact of removing co-payments on treatment adherence. High levels of uncertainty surround all key effectiveness inputs to the model, which make the overall results quite uncertain. Validity of estimate of measure of benefit The authors did not derive a summary measure of benefit and hence a cost-consequences analysis was performed. This was acceptable given that the full coverage strategy was dominant. The study did not include quality of life measurements and the time horizon was short, but this was consistent with the objective of the study which was to assess the economic case for insurers eliminating the co-payments of combination pharmacotherapy.
Validity of estimate of costs The analysis was performed from the perspective of a third-party payer. It included all the relevant categories of cost, assuming that insurers are not required to compensate patients or employers for impact on productivity. Some relevant costs might have been omitted from the analysis as it was not clear whether insurers would not pay for costs of events that do not result in hospitalisation. The lack of detail around the costs of events means that it is difficult to judge whether all the costs of care were included. Discounting was appropriate to the 3-year time horizon, but was not applied. The price year was unclear and an inflation index was not used to standardise the various cost estimates. The costs and the quantities were not reported separately and uncertainty in the total costs of events was not evaluated. There seems to have been an error in calculating the net savings.
Other issues The authors did not compare their findings with those from other studies, so it is not known how far their results agree. The authors also did not address the issue of generalisability to other settings. The results were reported in full and the conclusions reflected the scope of the analysis. The authors noted that they did not seek to evaluate the impact of providing coverage to those without insurance. Another limitation of the study was the lack of a lifetime horizon, although the authors argued that a shorter horizon was acceptable given the perspective and objective of the study.
Implications of the study The authors stated that their analysis supports a reconsideration of how drug formularies and insurance companies structure their benefits, particularly for medications of proven efficacy which continue to be underused. Although insurers feel little incentive to adopt benefit-based formularies in the face of high levels of patient switching, the analysis shows that benefits accrue within the first year of full coverage. These results have even clearer implications for a single-payer provider such as Medicare or the National Health Service. In contrast, the authors also called for a more rigorous examination of the benefits of full coverage in terms of its impact on adherence, outcomes, and the optimal combination of medications.
Source of funding Supported by Pfizer, BMS, Merck, COR, Schering-Plough and Sanofi-Aventis.
Bibliographic details Choudhry N K, Avorn J, Antman E M, Schneeweiss S, Shrank W H. Should patients receive secondary prevention medications for free after a myocardial infarction? An economic analysis. Health Affairs 2007; 26(1): 186-194 Indexing Status Subject indexing assigned by NLM MeSH Adrenergic beta-Antagonists /economics /therapeutic use; Aged; Aged, 80 and over; Angiotensin-Converting Enzyme Inhibitors /economics /therapeutic use; Aspirin /economics /therapeutic use; Cost Sharing; Cost-Benefit Analysis; Drug Therapy, Combination; Financing, Personal; Heart Failure /drug therapy /economics /epidemiology; Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors /economics /therapeutic use; Insurance Coverage; Models, Econometric; Myocardial Infarction /drug therapy /economics /epidemiology; Patient Compliance /psychology /statistics & Prescription Fees; United States /epidemiology; numerical data AccessionNumber 22007008033 Date bibliographic record published 31/07/2007 Date abstract record published 31/07/2007 |
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