The Dermatology Life Quality Index is a useful patient reported outcome measure in individuals with severe erythema nodosum leprosum: a post-hoc analysis of the Methotrexate and Prednisolone study - MaPs in ENL

BACKGROUND Erythema nodosum leprosum (ENL) is a severe inflammatory complication of leprosy associated with disability, morbidity and mortality. Impairment of health-related quality of life (HRQoL) in ENL has been reported using the Dermatology Life Quality Index (DLQI) and the 36-Item Short Form Health Survey (SF-36), the latter validated in people affected by leprosy. Understanding the correlation between these measures is important to determine whether the shorter dermatology-specific DLQI provides a valid and practical measure of HRQoL in ENL. OBJECTIVES To examine the relationship between DLQI and SF-36 scores in individuals with ENL using data from the Methotrexate and Prednisolone study in ENL (MaPs in ENL). METHODS A post-hoc analysis of prospectively collected HRQoL data from the trial sites in India, Indonesia, and Nepal of the MaPs in ENL multicentre randomised clinical trial was performed. HRQoL was assessed using the DLQI and SF-36 at enrolment and at weeks 24, 48 and 60. Associations between DLQI and SF-36 physical (PCS) and mental (MCS) component summary scores were evaluated using correlation analyses and multivariable linear regression at enrolment, and linear mixed-effects models during follow-up adjusted for age, sex, recruiting centre and enrolment SF-36 scores. RESULTS A total of 383 paired HRQoL assessments from 129 participants were analysed. At enrolment, HRQoL impairment was substantial (median DLQI 19, IQR 15-21; mean PCS 30.3 + - 7.3; mean MCS 33.3 + - 8.4). DLQI scores improved markedly during follow-up. Across all timepoints, DLQI was strongly inversely correlated with PCS and MCS (both p<0.001). In adjusted analyses, higher DLQI scores were consistently associated with lower PCS and MCS. At enrolment, each 1-point increase in DLQI was associated with a 0.66-point reduction in PCS and a 0.51-point reduction in MCS (both p<0.001). These associations remained strong during follow-up, with no evidence that they varied over time. CONCLUSIONS DLQI scores were strongly and consistently associated with SF-36 physical and mental health scores. These findings support the use of the DLQI as a practical patient reported outcome measure to assess the HRQoL associated with ENL and its change following treatment.