Low Adherence Rates for Patients with Severe Hemophilia

San Antonio—Prophylaxis with factor VII or IX has been shown to reduce bleeding episodes for patients with hemophilia A and B; however, a recent study finds that most individuals with severe hemophilia are not adherent to a routine prophylaxis regimen.

Edward P. Armstrong, PharmD, and colleagues presented this study at the NASP meeting during a poster session titled Adherence to Clotting Factors Among Persons With Type A or B Hemophilia.

Hemophilia A and B are congenital bleeding disorders caused by genetic deficiencies in clotting, which requires lifelong treatment. Patients with severe hemophilia experience frequent bleeding and recurrent spontaneous bleeding episodes into the soft tissue and joints. This can lead to joint damage and severe disability. Because the damage is progressive, it can lead to severely limited mobility of joints, muscle atrophy, and chronic pain.

This study aimed to determine adherence to replacement clotting factors for patients with hemophilia A and B during a 5-year period from October 1, 2006, through September 30, 2011. Patients included in the study were part of the US Department of Defense (DOD) database.

This retrospective, observational study used electronic medical records and administrative encounters/claims data. Demographic characteristics, such as age and sex, as well as treatment patterns of factor VII and factor IX products were collected using the DOD database. Hemophilia was stratified by severity—mild (>5%-50% normal clotting factor activity), moderate (1%-5% normal clotting factor activity), or severe (<1% normal clotting factor activity).

Patients were considered eligible if they had 2 healthcare encounters with a diagnosis of hemophilia A or B, had at least 2 medical or pharmacy encounters/claims for either factor VII or IX within the study period, and had at least 6 months of continuous enrollment in the DOD healthcare system. Patients were excluded if they had von Willebrand disease, or if they were receiving factor VII inhibitor bypassing activity or recombinant factor VIIa.

Of the 207 patients included in the study, 97.6% (n=202) were male, 74.9% (n=155) had hemophilia A, and 25.1% (n=52) had hemophilia B. Regarding the severity of hemophilia, 48.8% of the study participants (n=101) had mild hemophilia, 15.5% (n=32) had moderate, and 35.7% (n=74) had severe.

Medication adherence was assessed using prescription claims for clotting factors by examining sequential time periods of 180 days of continuous enrollment. Patients were deemed adherent if the ratio of days’ supply to observed days (eg, days within a specific timeframe) was ≥0.6.

Of the participants with mild hemophilia severity, 14% (n=28) were at least 60% adherent. For patients with moderate severity, 21% (n=32) were at least 60% adherent. Of the participants with severe hemophilia, 51% (n=36) were at least 60% adherent (P<.001 for all).

Among the adherent severe hemophilia patients, there was a wide distribution in adherence: 36.5% (n=27) were adherent ≤30% of the time; 29.7% (n=22) were adherent 31% to 70% of the time; and 33.8% (n=25) were adherent ≥71% of the time.

In conclusion, the study authors said that most patients with severe hemophilia were not adherent to a routine prophylaxis regimen despite limited financial barriers due to the DOD healthcare network.

A study limitation noted by the investigators was that the study included mostly children, which may be relevant to overall adherence. A sub-analysis according to age groups may add more to future studies.

This study was funded by Biogen Idec.