Development and validation of a questionnaire on 'Satisfaction with dermatological treatment of hand eczema' (DermaSat)
1 Department of Methodology, School of Psychology, Universidad Autónoma de Madrid, Madrid, Spain
2 Occupational Dermatology Department, Escuela Nacional de Medicina del Trabajo (National School of Occupational Medicine), Instituto de Salud Carlos III, Madrid, Spain
3 Dermatology Department, Hospital Sant Pau i Santa Creu de Barcelona. Barcelona, Spain
4 Dermatology Department, Hospital General Universitario de Valencia, Valencia, Spain
5 Basilea Pharmaceuticals Iberia S.L., (Fernando el Santo 15), Madrid, (E-28010), Spain
Health and Quality of Life Outcomes 2010, 8:127 doi:10.1186/1477-7525-8-127Published: 5 November 2010
To develop a self-administered short questionnaire to assess patient satisfaction with medical treatment for hand eczema (dermatitis) with good psychometric properties.
The content of the questionnaire was determined on the basis of clinical consultation with groups of patients, from studying the existing instruments, and from discussions with a panel of seven experts. A first draft version containing 38 items organised in six dimensions was tested on a pilot sample of patients to assess its legibility. The extended version was then tested on a sample of 217 patients of both genders enrolled at 18 hospitals representative of the national distribution. The questionnaire was supplied together with the Morisky-Green compliance questionnaire, the health-related quality of life (HRQL) SF-12 questionnaire, and a visual analogue scale (VAS) of perceived health status to assess concurrent validity. The dimensionality was reduced by means of exploratory factor analysis, and reliability was evaluated on the basis of internal consistency and two halves reliability estimates. Item discriminant capability and questionnaire discriminant validity with respect to known groups of patients (by gender, principal diagnosis, age, disease severity and treatment) were also assessed.
The reduction and validation sample was composed of 54% women and 46% men, of various educational levels with an average age of 43 years (SD = 13.7). Of those who responded, 26% were diagnosed with hyperkeratotic dermatitis of the palms and 27% of the fingertips, and 47% with recurring palmar dyshidrotic eczema. The questionnaire was shortened to a version containing 17 items grouped in six dimensions: effectiveness, convenience, impact on HRQL, medical follow-up, side effects, and general opinion. Cronbach's alpha coefficient reached a value of 0.9. The dimensions showed different degrees of correlation, and the scores had a normal distribution with an average of 58.4 points (SD = 18.01). Treatment satisfaction scores attained correlations between 0.003 and 0.222 with the HRQL measures, and showed higher correlations with the effectiveness (r = 0.41) and tolerability (0.22) measures, but very low correlation with compliance (r = 0.015). Significant differences were observed between some diagnoses and treatments.
The shortened questionnaire proved to have good psychometric properties, providing excellent reliability, satisfactorily reproducing the proposed structure and supplying evidence of validity.