The Hyperhidrosis Disease Severity Measure-Axillary: Conceptualization and Development of Item Content
July 2018 | Volume 17 | Issue 7 | Original Article | 707 | Copyright © July 2018
Brandon M. Kirsch MD,a Laurie Burke MPH,b Jeremy Hobart MD PhD,c David Angulo MDa Patricia S. Walker MD PhDa
aBrickell Biotech, Inc., Research and Development, Boulder, CO bLORA Group, LLC, Regulatory and Scientific Affairs, Royal Oak, MD and University of Maryland School of Pharmacy, Baltimore, MD cPlymouth University, Clinical Trials and Health Research, Plymouth, UK
INTRODUCTION: Patients with primary axillary hyperhidrosis (AHH) suffer from a variety of symptoms. Improved patient-reported outcome (PRO) measures are needed to better assess and categorize the severity of AHH symptoms experienced by patients because the widely used Hyperhidrosis Disease Severity Scale (HDSS) is a single-item measure that cannot capture the broad scope of disease impact. METHODS: The Hyperhidrosis Disease Severity Measure—Axillary (HDSM-Ax) was developed for determining the severity of excessive sweating in patients with primary focal AHH based on face-to-face concept elicitation interviews with 58 AHH patients, a literature review, and expert clinical input. Two waves of face-to-face cognitive interviews (n=26 and n=27) were conducted to evaluate HDSM-Ax clarity and relevance. Additional interviews (n=5) were conducted to confirm content. Adding Rasch Measurement Theory (RMT) analyses allowed for an iterative streamlined approach to documenting content validity and other cross-sectional measurement properties of the new HDSM-Ax measurement. RESULTS: The 11-item HDSM-Ax PRO scale (0-4 scale per item; 0-44 total scale) represents an AHH symptom range of 0 (no sweating) to 44 (worst possible sweating). Content validity of the HDSM-Ax was documented by showing that chronologically-grouped interviews demonstrated saturation in AHH symptom severity concepts. Cognitive debriefing interviews provided evidence that item content is complete, comprehensible, meaningful, and relevant. RMT-based exploration indicated that targeting of the HDSM-Ax was adequate, suggesting good matching between items and persons; item fit was adequate, suggesting a clinically cohesive scale; and items appeared to be stable between subgroups, thereby supporting a summary score. CONCLUSIONS: The HDSM-Ax is a well-developed measure of AHH severity based on patient-reported signs and symptoms. It is a superior measure to the HDSS and can be used in clinical research and clinical practice to quantify changes in symptom severity in response to treatment. J Drugs Dermatol. 2018;17(7):707-714.
Hyperhidrosis is a disorder of excessive sweating that can be idiopathic (primary) or secondary to medical conditions or medications.1 Primary hyperhidrosis (axillae, hands, and feet) affects 3-5% of the US population and is believed to be caused by overactive cholinergic response of the sweat glands.1,2 It has a significant effect on psychological and physical health, as well as work and daily activities.3 Appropriate patient care requires the ability to accurately evaluate symptoms and treatment response. Given the difficulty of quantifying and interpreting laboratory-based measurements of hyperhidrosis, such as gravimetric sweat production,4 assessing impact through patient-reported outcome (PRO) measurement is central to confirming the diagnosis, establishing the severity, and evaluating the treatment impact.The widely used Hyperhidrosis Disease Severity Scale (HDSS) is a quick and easy PRO to administer. However, it consists of a single question. In assessing complex, clinically relevant domains, a single-item question cannot capture the broad scope of impact on a patient. These are scientifically weak measures with limited reliability, validity, and ability to detect change.5 Additionally, the 4 possible responses to the HDSS incorporate 2 variables (tolerability and impact on daily life) in each response rather than separately assessing each variable. This does not allow for a different level of effect for each variable. Thus, the HDSS is a useful way of classifying subjects with hyperhidrosis, but it is inadequate for quantifying symptom severity6 and measuring clinical trial outcomes. As such, the HDSS does not meet US Food and Drug Administration (FDA) requirements for well-defined and reliable outcome assessments in primary axillary hyperhidrosis (AHH) clinical trials.7