Medication beliefs are associated with medication adherence in patients with psoriasis using systemic therapies: findings from the Investigating Medication Adherence in Psoriasis study

Medication adherence is a major barrier to optimizing the effectiveness of available therapies; however, few high-quality studies have examined adherence to systemic therapies used for psoriasis. We assessed whether patients with psoriasis can be categorized into groups with similar medication beliefs,and examined the relationship between belief group member-ship with adherence to systemic therapy and psychological distress. Cross-sectional data from 565 patients with moderate-to-severe psoriasis using a systemic therapy for ≤ 2 years were collected from 35 dermatology clinics across England:685% prescribed a biologic and 315% prescribed a conventional systemic therapy. A questionnaire assessed patients’medication beliefs (Beliefs about Medicines Questionnaire),psychological distress (Hospital Anxiety and Depression Scale)and medication adherence [Medication Adherence Report Scale(MARS)], with a score ≤ 38 on the MARS indicating non adherence. The optimal number of medication belief groups was identified using latent profile analysis (LPA). In total, 215%were classified as non adherent to systemic therapy, with a higher proportion of patients using a conventional systemic classified as non adherent (313%) compared with those usinga biologic (168%). The LPA model-fit statistics supported athree-group model; each group reported strong and positivebeliefs in the necessity of their systemic therapy and perceivedtreatment controllability, but differed in their level of concernabout systemic therapies and medicines in general; group 1(220%) reported the strongest concerns, followed by group 2(640%), with group 3 (140%) reporting the weakest con-cerns. The proportion of patients classified as nonadherent sig-nificantly differed by belief group (v2= 94, P = 001), with non adherence highest in group 1 (287%), followed by group 2 (213%) and lowest in group 3 (104%). There were significant differences in level of anxiety (H = 771, P = 002) and depression (H = 191, P < 001) between the three belief groups, with group 1 reporting the highest level of anxiety[median 75, interquartile range (IQR) 325–110] and depression (median 600, IQR 200–975), compared with group 2 (median 600, IQR 325–900, and median 400,IQR 100–700, respectively) and group 3 (median 600, IQR200–900, and median 300, IQR 100–700, respectively).Significant proportions of patients with psoriasis using sys-temic therapies reported nonadherence. Patients can be catego-rized into groups with similar medication beliefs. Patients with conflicting medication beliefs, holding strong beliefs in medication necessity and strong medication concerns, reported higher non adherence and higher levels of psychological dis-tress. Assessing medication beliefs may help identify those most likely to experience self-management difficulties and have poorer medication outcomes.