Convergent Validity of Suffering and Quality of Life as Measured by The Hidradenitis Suppurativa Quality of Life

Abstract Background Hidradenitis suppurativa (HS) is a painful chronic, recurrent inflammatory skin disease with great impact on health‐related quality of life (HRQOL). Recently, Hidradenitis SuppuraTiva cORe outcomes set International Collaboration (HISTORIC) established HRQOL as a core domain set for HS clinical trials and developed the Hidradenitis Suppurativa Quality of Life (HiSQOL) as a validated outcome measurement instrument. Objectives To provide further convergent validity of HiSQOL by comparing it to Dermatology Life Quality Index (DLQI) and Pictorial Representation of Illness and Self Measure‐Revised 2 (PRISM‐R2). Methods In this cross‐sectional study, 103 participants completed HiSQOL, PRISM‐R2 and DLQI. PRISM‐R2 is an instrument designed to measure suffering and reports the two measures, Illness Perception Measure (IPM) and Self‐Illness Separation (SIS). Correlation analyses were performed including a sub‐analysis for a subgroup of patients with high scores in the HS‐specific domains of HiSQOL. Results A very strong correlation was found between HiSQOL and DLQI (ρ = 0.93, P < 2.2 × 10−16, (95% CI: 0.89;0.95)), and moderately strong correlations were found between HiSQOL and SIS (ρ = −0.73, P < 2.2 × 10−16, (95% CI: −0.81; −0.62)) and DLQI and SIS (ρ = −0.70, P < 2.2 × 10−16, (95% CI: −0.79; −0.59)). IPM was positively associated with HiSQOL and DLQI and negatively with SIS. Conclusions HiSQOL is a valid measure of quality of life for HS patients, and we suggest that HiSQOL can be used as a measure of suffering as well.