Actinic keratosis area and severity index is not correlated with photodynamic therapy procedural pain

The Actinic Keratosis Area and Severity Index (AKASI) is a validated quantitative tool used to measure the severity of actinic keratoses. Given the success of AKASI in measuring outcomes and therapies related to actinic damage, we hypothesized that AKASI would be correlated to photodynamic therapy (PDT)-related pain. The aim of this study was to evaluate AKASI's correlation with PDT-associated pain for patients with AKs being treated with 5-Aminolevulinic acid (ALA) PDT.

Thirty consecutive patients being treated for AKs with ALA PDT on the face and/or scalp were recruited from a single center. The AKASI of the treated areas were collected. The patient underwent a standard treatment with ALA-PDT for a total of 10 J/cm2 to treated area. Immediate post-procedural pain scores were measured using a visual-analog pain scale. Pain and AKASI scores were analyzed using Pearson's correlation coefficient.

AKASI was not correlated to pain score (Pearson correlation coefficient was 0.027, p = 0.87). In sub-group analyses, there was no strong correlation between the scalp AKASI or face AKASI and respective pain scores (p = 0.59 and p = 0.38, respectively). Furthermore, there was no strong correlation between the individual components of AKASI and pain score: distribution (p = 0.26), erythema (p = 0.66) and thickness (p = 0.43).

There is no correlation between the AKASI score and perceived pain from PDT. Therefore, the need for pain relief using a fan and evaporative cooling should be anticipated for all patients. We feel that this negative result is noteworthy as it supports mechanisms outside of AK destruction as the cause of immediate PDT-related pain.