Shedding Light on the "Hidden Psoriasis": A Pilot Study of the Inverse Psoriasis Burden of Disease (IPBOD) Questionnaire

While burden of disease (BOD) data exists for plaque psoriasis, and to a lesser extent other phenotypes of psoriasis, there is no published data on the impact of inverse (intertriginous) psoriasis. We sought to assess the overall BOD among patients with inverse psoriasis (IP). We introduce the Inverse Psoriasis Burden of Disease (IPBOD) questionnaire and compare it to the Dermatology Life Quality Index (DLQI). In this cross-sectional pilot study, we administered the IPBOD and the DLQI to 16 patients. We present the initial psychometric properties of the IPBOD survey. We used Spearman's correlation coefficients to compare the two questionnaires on overall performance and in specific domains. Our cohort had an average age of 55.6 (SD 16.6) years, was predominantly female (68.8%), and white (875%). 87.5% of patients had a second psoriasis subtype. A majority of patients reported some effect of IP on pain (n=14, 87.5%). Thirteen (81.3%) patients reported some effect on depressed mood or anxiety/worry. Overall, the largest effect was on body self-image (93.8% reporting an effect). The average DLQI score was 8.5/30, higher than average DLQI scores reported in patients with plaque psoriasis or psoriatic arthritis. Average IPBOD score was 4.9/10. The reliability of IPBOD was good (overall Cronbach's alpha = 0.89, individual items' range 0.88 0.91). Correlations between IPBOD and DLQI were: overall (Spearman's P=0.650, P=0.006), symptoms (P=0.462, P=0.072), daily activities (P=0.507, P=0.045), leisure (P=0.633, P=0.008), interpersonal function (P=0.728, P=0.001), and work and school (P=0.427, P=0.100). IP has a profound impact on patients' lives and the results of this pilot study suggest that the IPBOD questionnaire may be a useful disease-specific tool for measuring the BOD of IP.