Adherence to treatment of chronic skin diseases is important to treatment outcomes. In the treatment of psoriasis,adherence is poor, with reported rates between 22% to 67%.1 However, adherence may be better with biologic agents, followed by oral medications, phototherapy, and then topical agents.2,3
Literature on adherence to biologics in the treatment of psoriasis is limited; Bhosle et al reported an adherence rate of 66% with TNF-alpha inhibitors.4 Measuring adherence to biologics is difficult since traditional means of monitoring whether a patient is taking their medication cannot be utilized; there are no pills to count or bottles to weigh. In the treatment of rheumatologic diseases, where adherence to biologics has been more extensively studied, persistence, which refers to the rate of continued drug use for a defined duration, has been the more commonly used method to measure adherence.5 This is in contrast to adherence,which refers to the extent a patient uses a medication as prescribed. Self-reported adherence rates are often used but are not reliable since patients tend to over report their adherence in questionnaires and medication diaries.6,7 Electronic monitoring systems were used in a small study and found that adherence in the treatment of psoriasis patients with adalimumab was variable and in some cases poor. Patients averaged 19.8 days between injections that were scheduled every 14 days in the non-intervention group, and 20.7 days in the intervention group, with the number of days between doses varying between 6 and 93.8
Ustekinumab is an interleukin (IL)-12 and IL-23 blocker administered by office injection (the FDA has recently approved ustekinumab to be self-administered, like the injectable TNF-α inhibitors) and approved for the treatment of psoriasis. Dosing is weight based, 45 mg and 90 mg (recommended for patients > 100 kg), administered as a loading dose 1 month after initial injection, with subsequent doses every 12 weeks.9 As ustekinumab has been administered in the office setting, adherence to ustekinumab can be determined by chart review. The goal of this study is to describe adherence rates to ustekinumab in psoriasis patients, including the number of injections administered, the time between injections, and reasons for nonadherence.
This was a single center, retrospective study involving a chart review of patients with a diagnosis of psoriasis and administration of ustekinumab seen at the Wake Forest School of Medicine Department of Dermatology clinic between October 1, 2009 and June 1, 2013. Approval for this study was obtained from Wake