Hyperhidrosis Quality of Life Index (HidroQoL©): further validation and clinical application in patients with axillary hyperhidrosis using data from a phase III randomized controlled trial*

Abstract

Summary Background The Hyperhidrosis Quality of Life Index (HidroQoL©) is a validated patient‐reported outcome measure capturing the quality of life of people affected by hyperhidrosis. Objectives We aimed to extend the validity evidence to physician‐confirmed diagnosis of primary axillary hyperhidrosis. Methods Data from a phase III randomized placebo‐controlled clinical trial were used (n = 171). Confirmatory factor analysis was carried out to confirm the a priori two‐factor structure of the HidroQoL. Internal consistency was assessed using Cronbach’s α. Intraclass correlation coefficients (ICCs) were calculated to evaluate test–retest reliability after days –7 to –4. Convergent validity was assessed using correlations with the Dermatology Life Quality Index (DLQI), the Hyperhidrosis Disease Severity Scale (HDSS) and gravimetric sweat production. Known groups were analysed to evaluate discriminative validity. Responsiveness after 29 days was assessed and minimal important difference (MID) values were calculated using both anchor‐ and distribution‐based approaches. All analyses were carried out for total HidroQoL and its two domains. Results The two‐factor structure of the HidroQoL was confirmed. Internal consistency and test–retest reliability were strong (Cronbach’s α 0·81–0·90; ICCs 0·89–0·93). Correlations with other outcome measures were in line with a priori hypotheses. The HidroQoL discriminated between different severity groups (P ≤ 0·001) and showed sensitivity to change towards improvement (P < 0·001). An MID value of 4 is proposed for the total scale. Conclusions This study supports excellent measurement properties including clinical applicability of the HidroQoL in primary axillary hyperhidrosis and suggests a MID of 4 be applied to clinical trial data.

A glycopyrronium bromide 1% cream for topical treatment of primary axillary hyperhidrosis: efficacy and safety results from a phase IIIa randomized controlled trial*

“…Questions are rated on a 3‐point scale and a summary score for each domain and overall score is calculated. In 2020, the HidroQoL was revalidated specifically for primary axillary HH and the minimally clinically important difference (MCID) for treatment response has been defined as an improvement of ≥ 4 points 26 …”

Measurement properties of patient-reported outcome measures (PROMs) in hyperhidrosis: a systematic review

“…Five included studies reported on the DLQI [3,26,41,43,46]; three on the HQLQ [1,6,35], the HidroQoL [9,18,20] and the HDSS [39,46,47], respectively; two on the SF-36 [38,46], the Hyperhidrosis Disease Severity Measure-Axillary (HDSM-Ax) [16,22], as well as the Hyperhidrosis Scale (HS) [21,35]; and one each on the ASDD and its child version (ASDD-C) [34], the Hyperhidrosis Impact Questionnaire (HHIQ) [25], the Illness Intrusiveness Rating Scale (IIRS) [5], the Hyperhidrosis Questionnaire (HQ) [24], the Sweating Cognitions Inventory (SCI) [52] and the Table 3 GRADE approach for grading the quality of evidence [36] Starting point: assumption that the evidence is of high quality. Information on how to downgrade is described in the COSMIN user manual [31].…”

“…Both reports showed ceiling effects for most of the items. According to Gabes et al [9], 26-91% of the patients chose the highest response category. Floor effects were found by Kamudoni [18] for 13 items of the HidroQoL.…”

“…However, no further structure in the missing data was apparent. Minimal important difference (MID) values of 3 to 4 were proposed for the HidroQoL by Kamudoni [18] and Gabes et al [9]; differences in values are likely due to a more homogenous study population in the latter study. Hobart et al [16] estimated meaningful change scores of the HDSM-Ax and stated that a change in the HDSM-Ax total score of one point represents a clinically meaningful change in axillary hyperhidrosis severity.…”

“…Several PROMs that cover diverse constructs have been developed and reported in the literature for patients with hyperhidrosis, for instance, the Hyperhidrosis Quality of Life Index (HidroQoL) [20], the Hyperhidrosis Disease Severity Scale (HDSS) [47] or the Axillary Sweating Daily Diary (ASDD) [34]. In clinical research and practice, not only hyperhidrosis-specific PROMs are used but also skinspecific or more generic PROMs such as the Dermatology Life Quality Index (DLQI) [9] or the short-form health survey (SF-36) [18,38].…”