Examining the use of biologic therapies in the management of psoriasis: understanding drug utilisation, impact on quality of life and drug survival.

UoM administered thesis: Phd

Abstract

Objectives: The aims of this thesis were twofold. Firstly, to examine the utilisation patterns and comparative effectiveness of adalimumab, etanercept and ustekinumab on improvements in health related quality of life (HRQoL) in patients with psoriasis in routine clinical practice; and secondly, to assess the differential drug survival of second-line use of these therapies and determine whether the reason for failing the first-line biologic therapy was predictive of the reason for discontinuation of the second biologic therapy. Methods: Data from patients with psoriasis registered with the British Association of Dermatologists Biologic Interventions Register (BADBIR) were used in this thesis. The drug utilisation study assessed treatment modifications (dose escalations/reductions, switches, discontinuations and restarts of biologic therapies) during the first year of treatment. The time-trend method, comparing the cumulative dose (CD) patients received with the recommended cumulative dose (RCD) per product prescribing information, was used to assess the dosing patterns. Patterns of use of conventional systemic treatments concomitantly with a biologic therapy were also examined. Changes in HRQoL were assessed using the Dermatology Life Quality Index (DLQI) and European Quality of Life - 5 Dimensions (EQ-5D) at 6 and 12 months. Multivariable logistic and linear regression models were developed to identify factors associated with achieving a DLQI of 0 or 1 and improvements in the EQ5D utility score, respectively. Drug survival with second-line biologic therapies was examined using Kaplan-Meier survival analysis and predictors for drug discontinuation were analysed using multivariable Cox Proportional Hazard models. Results: During the first year of treatment, 77% of patients continuously used their biologic therapy, while 3% restarted therapy after a break of at least 90 days, 3% discontinued therapy, and 18% switched to an alternative biologic therapy. Most patients (86%) received the RCD of the biologic therapy, although 8% were exposed to a higher CD. In total, 749 patients (25%) used conventional systemic therapies concomitantly with a biologic therapy at some stage; methotrexate was used most commonly (458; 61%). Of those using combination therapy, 454 patients (61%) continued the use of the conventional systemic therapy for >120 days after the start of the biologic therapy. At 6 months, the median (interquartile range) DLQI and EQ-5D improved from 18 (13-24) and 0.73 (0.69-0.80) at baseline to 2 (0-7) and 0.85 (0.69-1.00), respectively (p

Details

Original languageEnglish
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Award date31 Dec 2017