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Background: Increased incidence of myocardial infraction (MI) and improved post-MI survival have led to an increase in the incidence of post-MI heart failure (HF) and in the cost of care attributable to post-MI HF.
Objectives: 1) To estimate the potential 1-year cost savings if HF could be prevented in post-MI patients. 2) To illustrate the biases that may arise in using alternative estimators to model expenditure data.
Methods: We use data for years 1998, 1999 and 2000 from a large claims database. After applying the exclusion criteria, we group eligible patients into those with and without HF subsequent to MI using inpatient, outpatient and prescription records. We model the total medical expenditures for each patient over the 1-year period post index date. Covariates include HF, age, sex, death and comorbidities at index hospitalization, type of insurance, procedures performed, year and the type of MI. The estimators that we consider are the ordinary least squares (OLS) regression, log-transformed OLS regression with and without heteroscedastic smearing , the gamma regression with log-link and the extended estimating equations (EEE) model that estimates both the link and variance parameters for the data along with the regression coefficient.
Results: 15,116 patients were eligible for the study. Completed one-year follow-up data were available for 7621 patients. No significant differences were found in observed variables between those with complete one year data and those without. Significant differences in estimated cost-savings were found between estimators. The EEE model estimator was found to be more appropriate than other estimators based on a broad set of goodness of fit tests and tests of over-fitting. Based on this estimator, the potential 1-year cost-savings due to preventing HF in post-MI patient who develop HF was estimated to be $14700 (1135). The cost-savings decreased with increasing age.
Conclusions: Careful selection of estimator is important for modeling cost data. The EEE estimator appears to outperform alternative estimators studied. We find that preventing HF in post-MI patient can produce substantial savings in health care costs. The estimates provided here can serve as a guide in conducting cost-effectiveness analysis of the new treatments that are aimed to prevent heart failure in patients with myocardial infarction.
See more of Oral Concurrent Session B - Methodological Advances
See more of The 26th Annual Meeting of the Society for Medical Decision Making (October 17-20, 2004)