The use in electronic format of patient reported outcome measures (PROs) has been increasing, though they are not always validated against their paper counterparts. The aim of this study was to validate a novel iPad® application version of the DLQI concerning score consistency, compared to the conventional paper-based version. Patient preference and acceptability were also recorded for each version.
The study employed a randomized cross-over design using a within-subjects comparison of the two questionnaire formats. International Society for Pharmacoeconomics and Outcomes Research guidelines were followed. Subjects aged over 18 years with any confirmed skin condition were recruited from a teaching hospital dermatology outpatient clinic. 
104 patients were recruited, mean age=52 years (SD +/-18.7; 43% male). The most common diagnoses were psoriasis (39%), ‘skin lesion’ (19%) and eczema (13%). The intra-class correlation coefficient (ICC) showed high concordance between the total DLQI scores from paper and iPad® versions (ICC = 0.98; 95% CI 0.97-0.99). Patients took a median of 78 seconds to complete the electronic version and 73 seconds for paper (p<0.05): 76% preferred the electronic version. Patients found both paper and iPad® versions easy to use (mean 9.4 ± 1.3 for paper and 9.6 ± 1.3 for iPad®, 10 = very easy).
There is high concordance, and thus equivalence, between the iPad® and paper versions of the DLQI with a clear patient preference for the iPad version. This first documented validation of the electronic format DLQI has reassuring implications for researchers and patients worldwide.

Validation of the electronic version of the Dermatology Life Quality Index (DLQI)