Tele-assessment of Psoriasis Area and Severity Index: a study of the accuracy of digital image capture

The implementation of remote Psoriasis Area and Severity Index (PASI) determinations would greatly enhance the delivery of specialist dermatological care to patients with severe psoriasis unable to attend face-to-face dermatological consultations. Here we investigate the feasibility of the remote determination of PASI scores by comparing the results of face-to-face with digital image assessment.

Twelve patients with confirmed psoriasis were recruited for the study. Initially, two dermatologists scored the PASI at the patients' usual scheduled face-to-face visits, at which time standardized digital images were obtained. PASI scoring based on digital images was then performed on two separate occasions by three dermatologists with a time-interval period between assessments, facilitating an assessment of score reproducibility. Linear weighted kappa statistics were applied to the PASI scores to ascertain agreement between sets of observations.

While we found a moderate (κ = 0.51) agreement between the face-to-face scores, there was very good (κ = 0.83) agreement between the first round of telescores and moderate (κ = 0.60) agreement between the second round of telescores. Comparison between the face-to-face and telescores revealed good (κ = 0.67 and 0.63) agreement for the scorers respectively.

We demonstrate that PASI scores can be determined with moderate to good accuracy by dermatologists using standardized digital images. Our results imply the implementation of a tele-PASI service may be a practical and effective adjunct to the dermatological care of patients with severe psoriasis where incapacity or distance prevent the realisation of face-to-face consultations.