Study objectives: To examine the sources of the direct medical costs of α1-antitrypsin (AAT) deficiency based on survey data from affected individuals.
Background: Prior research has reported the total cost of AAT deficiency but has not examined the specific components of the direct medical costs of affected individuals.
Methods: In order to detail the sources of the direct medical costs, we sent surveys to 688 respondents of a previous survey. We estimated the costs in three ways, which differed in the method of managing missing values. With method 1, the group mean value of cost per unit of utilization, multiplied by the occurrences of utilization, was used to replace the missing value. Two sensitivity analyses (ie, methods 2 and 3) were conducted to test the robustness of our estimate. With method 2, values of zero were entered for all missing values. With method 3, the missing values were replaced by the group mean value. The Wilcoxon test was used to test the cost differences between patients of different phenotypes. All cost data were expressed in 1998 US dollars.
Results and conclusions: Two hundred ninety-two individuals responded to the survey. The annual total health-care costs were high (mean range, $36,471 to $46,114; median range, $12,485 to $37,100 [according to the method for managing missing data]) for AAT deficiency. The total costs for individuals with the PI*ZZ phenotype exceeded those for individuals with a non-PI*ZZ phenotype. The use of IV augmentation therapy accounted for more than half of all direct medical costs for the respondents. Besides the costs for therapy with α1-proteinase inhibitor (Prolastin; Bayer; West Haven, CT), other major cost sources were prescription drugs other than α1-proteinase inhibitor, hospitalization, health insurance, and physician visits.