Improvement of Psoriasis Patients' Adherence to Topical Drugs

Background Psoriasis is a chronic inflammatory skin disease affecting 2-4% of the Western adult population. It is associated with many comorbidities, negatively affects quality of life and is a socioeconomic burden for patients and society. Topical drugs are the recommended first-line treatment for mild-to-moderate psoriasis, but adherence rates are low, which is a barrier for treatment success, resulting in a need for systemic or biological treatments, which are associated with more severe adverse events and are more expensive than topical drugs. However, improved adherence to topical drugs is associated with improved efficacy. That is why there is a need for improving psoriasis patients' adherence to topical drugs.

As a supplement to the introduction of new and advanced technology, there is a need for more studies on how to optimize the available healthcare professionals in dermatology clinics. Since dermatologists are a limited resource, there is a need to study how other healthcare professionals, e.g., hospital nurses and pharmaconomists at the pharmacies, can support psoriasis patients in their use of topical drugs.

Hypothesis

A patient-supporting intervention delivered by dermatologists, dermatology nurses and pharmaconomists significantly reduces psoriasis patients' severity of psoriasis compared to standard patient support.

Aims

The aim of the project is to test whether an individualized patient-supporting intervention delivered to psoriasis patients by dermatologists, nurses and pharmaconomists at a dermatology hospital clinic can: 1) reduce the severity of psoriasis, 2) improve quality of life, and 3) improve adherence to prescribed topical drugs.

Ethical considerations

All participants will be fully informed of the purpose of the study, and the study will be performed in accordance with the ethical principles in the Belmont report.

Materials and methods

The study is an investigator-initiated, single-centre, assessor-blinded, parallel group superiority randomized clinical study. Before inclusion of study participants, the study will be approved by the local regional ethics committee.

We will include patients (18-85 years of age) with milder-to-moderate psoriasis.

Outcomes

Outcome measurements will be either patient-reported or assessor-blinded.

Adherence measurements

Primary adherence: Proportion of filled topical prescriptions.

Secondary adherence:

Amount of medication used according to weight of the remains in the used medication packages. Data will be assessed week 48.

Disease severity measurements

Disease severity will be measured by Lattice-System Physician's Global Assessment (LS-PGA) (15), and the quality of life will be measured by the Dermatology Life Quality Index (DLQI). This data will be assessed at baseline, weeks 12, 24, 36 and 48.

Recruitment

Psoriasis patients who use topical treatments and are referred to the Department of Dermatology at Odense University Hospital will be recruited to the project until there is a sufficient number of participants included (n=100).

Hypothesis and expected number of participants

Our null hypothesis is that there is no difference in reduction of psoriasis between the intervention and non-intervention groups.

The sample size was calculated based on data from a previous project with consumption data for the use of prescribed calcipotriol betamethasone dipropionate cutaneous foam over 4 weeks. We expect an 20% difference in the LS-PGA, power 80%, two-sided significance of 95%, allocation of 1: 1 and an expected dropout rate of 25%. When using an unpaired t-test, the calculation resulted in the inclusion of a sample size consisting of 80 participants.

Blinding and randomization

Blinding of the data assessors: When the data assessor obtains baseline data from the study participants, it will be entered by an electronic data collection tool.

Participants will be allocated 1: 1 to an intervention or non-intervention arm via a computer-generated block randomization. The data assessor will be blinded to the allocation.

Statistics

Analysis of the primary outcome: changes in LS-PGA

Changes in LS-PGA measurements from baseline to weeks 12 and from baseline to weeks 24, 36 and 48 will be compared between the two groups by linear mixed model for longitudinal data. LS-PGA will be presented in box plots. As a sensitivity analysis on LS-PGA, the analysis will be carried out excluding missing data and after 100 times multiple imputations by multivariate normal regression on LS-PGA data, without included covariates in addition to with an imputation including treatment, age, sex and smoking as covariates.

Analysis of secondary outcomes: Changes in DLQI and adherence

Changes in DLQI measurements from baseline to weeks 12, 24, 36 and 48 will be compared between the two groups by linear mixed model for longitudinal data. DLQI will be presented in box plots.

For the analysis of adherence (by filled prescriptions, weight and patient reported), we will dichotomize adherence rate with a selected cut-off of 80%, with adherence rates above 80% considered adherent (a cut-off typically used when studying adherence in chronic diseases) [7, 42]. We will compare the dichotomized adherences by using logistic regression.

The statistical analysis will be conducted by an experienced statistician blinded to the intervention. An interim analysis is not planned.

Discussion

This study will demonstrate whether an individualized, optimized patient support delivered by doctors, nurses and pharmaconomists to dermatological patients can optimize the use of topical treatment, reduce the severity of psoriasis and have socioeconomic benefits compared to standard treatment. If the study shows that individualized and optimized patient support is effective, it is intended for the intervention to be implemented in the clinic. In addition, we will work on implementing the intervention nationally by a translational process.

Results from the study may also be referred to other chronic dermatological disorders. The study may be used methodically as a model for additional research projects investigating medical adherence in other chronic skin diseases.

Inclusion criteria

Legally competent patients with milder-to-moderate psoriasis

Exclusion criteria

Incapable patients not diagnosed with psoriasis