title: The development and validation of a disease-specific quality of life measure in hyperhidrosis: the Hyperhidrosis Quality of Life Index (HidroQOL©).
abstract: OBJECTIVE
  To develop and validate a new disease-specific quality of life measure in hyperhidrosis for use in both routine clinical practice and clinical research.
  
  
  METHODS
  Interviews and focus group discussions with hyperhidrosis patients, reported elsewhere, provided the content for the measure validated in this study (n = 71). A panel of dermatologists (n = 5) and patients (n = 7) carried out content validation. Further, item reduction and the initial construct validation were carried out in a cross-sectional study (n = 595), using the unidimensional Rasch analysis and exploratory factor analysis. Subsequently, the construct validity, reliability and responsiveness of the revised measure were assessed in a longitudinal study (n = 260). Data collection for the item reduction and the final validation phases was entirely carried out online.
  
  
  RESULTS
  The expert panels judged the HidroQoL as content valid. Rasch analysis supported the revision of response options from five to three. Following removal of misfitting items, a set of 15 items showed optimal fit to the model (chi-squared statistic = 159.64, p = 0.07). Three additional items were retained on consideration of their importance to patients, resulting in an 18-item instrument. The items were grouped into two subscales, daily life activities and psychosocial life domains, based on results of the factor analysis. In subsequent construct validation, the HidroQoL correlated with the DLQI (r s = 0.6, p < 0.01). Reliability was high (internal consistency, Cronbach's alpha: overall scale = 0.9; test-retest reliability, Intra-class correlation = 0.9). The HidroQoL scores were sensitive to change in patients' disease severity (score change from baseline to follow-up after 15-35 days, Cohen's ES = 0.47).
  
  
  CONCLUSIONS
  This study has provided the initial evidence supporting measurement properties and the use of the HidroQoL instrument in both routine clinical practice and in research, for assessing quality of life impacts in hyperhidrosis.
authors.affiliation: Centre for Socioeconomic Research, School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Redwood Building, Kind Edward VII Avenue, Cardiff, CF 10 3NB, UK, pkamudoni@gmail.com.
authors.forename: P
authors.initials: P
authors.lastname: Kamudoni
authors.forename: B
authors.initials: B
authors.lastname: Mueller
authors.forename: M S
authors.initials: MS
authors.lastname: Salek
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D003430:Cross-Sectional Studies; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D006945:Hyperhidrosis / Q000523:psychology*; D008137:Longitudinal Studies; D008297:Male; D011594:Psychometrics; D011788:Quality of Life / Q000523:psychology*; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires