Comparison of hospital costing methods in an economic evaluation of a multinational clinical trial.

OBJECTIVES

To develop and evaluate strategies for estimating hospitalization costs in multinational clinical trials.

METHODS

Hospital cost estimates for eleven diagnoses were collected from twelve countries participating in a trial of therapies for congestive heart failure. Estimates were combined with U.S.-based diagnosis-related group weights to compute country-specific unit cost estimates for all reasons for hospitalization. Variations of hospital costing methods were developed. The unit cost method assigns a country-specific unit cost estimate to each hospitalization. The other methods adjust for length of stay using a daily cost (DC) estimate for each diagnosis, based on either the mean length of stay (DC-mean method) or the median length of stay (DC-median method) for each diagnosis in each country. Additional modifications were explored through adjustment of the distribution of daily costs incurred during a hospital stay.

RESULTS

The mean cost for all hospitalizations was dollars 10,242 (SD, 10,042) using the unit cost method, dollars 10,242 (SD, 12,760) using the standard DC-mean method, and dollars 13,967 (SD, 18,762) using the standard DC-median method. In comparisons of costs for all 5,486 hospitalizations incurred by a subset of 2,352 patients in the trial, the unit cost method provided 92% power to detect a dollars 1,000 cost difference. The standard DC-mean method provided 76% power, and the standard DC-median method provided 44% power.

CONCLUSIONS

Hospital costing methods that adjust for differences in length of stay require a significantly larger sample to attain comparable statistical power as methods that assign unadjusted unit cost estimates to hospitalization events.