Assessing the costs for clinical care of patients with high-responding factor VIII and IX inhibitors.

Summary.  The costs of haemophilia-related care and the impact of unusually expensive, or outlier, patients on these costs have been explored in numerous European, American and Canadian studies during the last decade. In particular, antibodies that neutralize infused factor VIII or IX (high-responding inhibitors) make treatment responses, and thereby costs, much less predictable. There is little debate that the health care costs of haemophilic patients with high-responding inhibitors are routinely higher and more variable than those of non-inhibitor patients. However, the extent to which this is attributable to the few outlier inhibitor patients whose expenditures tend to skew the data is not as clear. To compare the variation and range in health care expenditures among patients with inhibitors and those without, we reviewed data originally gathered during a 24-month period in 1995–1997 from a prospectively created cohort as part of a broader cost and utilization study conducted at a large haemophilia treatment centre. We conclude that although the use of outpatient factor replacement products was not significantly greater or more expensive among inhibitor patients, their hospital-related costs greatly increased overall expenditures. Among our study population, the overall costs associated with inhibitor patients are not only higher in absolute monetary terms, but also in terms of the degree of variation. This variation was demonstrated by: (i) the extremely wide range of costs over an extended timeframe among individual inhibitor patients when compared with those without inhibitors, and (ii) the much larger year-to-year variation in costs among the inhibitor group.