Background: Rheumatologists play an important role in the management of patients with Psoriatic Arthritis (PsA). With PsA being a multifaceted disease, it can be challenging to assess the impact of psoriatic skin symptoms, next to the musculoskeletal complaints. We have previously shown that a dermatology-specific Health-related Quality of Life (HRQoL) questionnaire provides insight into the burden of skin symptoms, in contrast to a general HRQoL questionnaire.1 When treating PsA patients, specific questions on skin symptoms are necessary in order to assess the burden of psoriasis.
Objectives: To create a set of questions that can easily identify PsA patients with a high psoriasis burden in daily rheumatology clinical practice.
Methods: Data from patients receiving usual care were used from the Dutch south west Psoriatic Arthritis (DEPAR) cohort, consisting of newly diagnosed PsA patients included between July 2013 and March 2020. The two dermatology-specific HRQoL questionnaires used were the Skindex-17 and Dermatology Life Quality Index (DLQI), both with a one-week recall period.
First, an exploratory principal component analysis (PCA) with varimax rotation was performed on both questionnaires combined, to identify underlying latent traits. Subsequently, items were dichotomized on their median frequencies. And a 2-parameter logistic (2PL) model was fitted for each latent trait. Item characteristic curves were plotted for each latent trait. Item selection took place based on the discrimination and difficulty of the items. Per latent trait, we selected 2 to 3 items distributed far apart across the latent trait. A flowchart was made with the selected questions.
Results: In total, 413 patients with completed Skindex-17 and DLQI questionnaires at baseline were included. Mean (sd) age was 50.3 (13.4) years and median (IQR) Psoriasis Area and Severity Index (PASI) score 2 (0.5-4.2). The PCA gave the best fit with two underlying clusters of questions, namely psychosocial (n=20) questions and questions regarding physical symptoms (n=7). Three questions were selected to assess psychosocial impact and two for impact of physical symptoms (Figure 1). Questions should be asked in chronological order.
Cluster 1: Psychosocial
The first question is if the patient was embarrassed by their skin condition. If answered with “never”, the patient experienced the lowest burden. When answered with “rarely/sometimes” or “often/always”, continue to the second question. Ask the patient if they tended to stay at home because of their skin condition. If answered with “never”, they experienced a higher burden. If answered with “rarely/sometimes” or “often/always”, continue to the last question. Ask the patient if their skin condition has prevented them from working or studying. If not, the patient experienced a higher burden and if answered with “yes”, they experienced the highest burden in this domain.
Cluster 2: Physical symptoms
First ask the patient how itchy, sore, painful or stinging their skin was. If they answer with “not at all”, they experienced the lowest burden. If answered with “a little/a lot/very much”, continue to the second question. Ask if their skin was irritated. If answered with “never/rarely/sometimes”, they experienced a higher burden. If answered with “often/always”, the patient experienced the highest burden in this domain.
Conclusion: We have created a practical guide for rheumatologists to distinguish PsA patients with a high psoriasis burden from those with a lower burden. With a minimum of two and a maximum of five questions, both psychosocial burden of psoriasis and burden of physical symptoms can be easily identified in daily clinical practice.
References: Kasiem FR, Kok MR, Tchetverikov I, Wervers K, Hazes J, Luime J, et al. AB0786 Impact of psoriasis severity on Health-Related Quality of Life in early psoriatic arthritis: results from real world data, the DEPAR study. Annals of the Rheumatic Diseases. 2020;79:1691-2.
Disclosure of Interests: None declared
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