Comparison of the paper-based and electronic versions of the Dermatology Life Quality Index: evidence of equivalence.

Background The use of patient-reported outcome measures in electronic format has been increasing. However, these formats are usually not validated or compared with the original paper-based formats, so there is no evidence that they are completed in the same way. Objectives To compare the conventional paper version with a web-based application ( iPad®) version of the Dermatology Life Quality Index ( DLQI) to assess equivalence of scores. Methods The study employed a randomized crossover design using a within-subjects comparison of the two formats of the questionnaire. International Society for Pharmacoeconomics and Outcomes Research ( ISPOR) guidelines were followed. Participants aged over 18 years with any confirmed skin condition were recruited from a teaching hospital dermatology outpatient clinic. Expected intraclass correlation coefficient ( ICC) was 0·9 (α = 0·05). Results A total of 104 patients were recruited, median age 53·5 years (interquartile range 37·3-67·8; 43% male). The ICC showed high concordance between the total DLQI scores from paper and iPad versions ( ICC 0·98; 95% confidence interval 0·97-0·99). Patients took a median of 78 s to complete the electronic version and 73 s for paper ( P = 0·008): 76% preferred the electronic version and perceived completion to take a shorter time. Conclusions There is high concordance and thus equivalence between the iPad and paper versions of the DLQI, with an ICC of 0·98, and a clear patient preference for the iPad version. [ABSTRACT FROM AUTHOR]