Identifying medication belief groups in psoriasis: a latent profile analysis

Abstract

Background Patients’ beliefs about illness and treatments are key drivers of medication adherence. We investigated how beliefs are linked, whether we could identify meaningful groups of patients with similar medication beliefs, and examined relationships between group membership and adherence. Methods Cross-sectional survey of 816 patients with moderate-severe psoriasis prescribed a biologic (injection) or conventional (tablet) systemic therapy recruited from 35 UK dermatology centres. Beliefs and medication adherence data were collected and theory-led group identification was made using latent profile analysis (LPA). Findings 22% of patients using a self-administered systemic therapy were classified as ‘non-adherent’; just over half of those classified as intentionally rather than unintentionally non-adherent. A higher proportion of patients using a conventional systemic were classified as non-adherent (28.7%) compared with those using a biologic (16.1%); χ2= 13.7, p ≤ .001. LPA supported a 3-group model. Each group expressed strong and positive beliefs in treatment necessity and controllability, but differed in their level of medication concerns. Group 1 (26% of the sample) reported the strongest concerns, followed by Group 2 (61%), with Group 3 (13%) reporting the weakest concerns. A higher proportion of patients in Group 1 were classified as intentionally non-adherent (19.7%) compared with Groups 2 and 3 (9.4%), χ2= 11.7, p = .001. There was no relationship between belief groups and unintentional non-adherence (p = .83). Discussion Many patients express unresolved medication concerns, even if they believe their medication is necessary and effective. LPA offers a novel approach for identifying those most likely to experience adherence difficulties.