Reliability of counting actinic keratoses before and after brief consensusdiscussion - The VA Topical Tretinoin Chemoprevention (VATTC) Trial

Objective: To assess the reliability of counts of actinic keratoses (AKs) a nd the effect of a brief joint discussion of discrepancies on that reliabil ity. Design and Intervention: Seven dermatologists independently counted AKs on the face and ears before and after a brief joint discussion of discrepancie s. Setting and Patients: A volunteer sample of 9 patients from the ongoing VA (Department of Veterans Affairs) Topical Tretinoin Chemoprevention (VATTC) Trial. All participating individuals are veterans and have had 2 or more ke ratinocyte carcinomas (basal or squamous cell carcinoma) in the 5 years bef ore enrollment in the study. Main Outcome Measure: Standard deviation of estimates of the Poisson regres sion parameter for the dermatologists. Results: Substantial variation was found among the dermatologists in their AK counts. The SD of the parameter estimates for the dermatologists decreas ed from 0.45 to 0.24 after the brief joint discussion, a 47% decrease (P=.0 76). The variation attributable to the dermatologists also decreased substa ntially (chi (2)(6) decrease, 94 to 12). Conclusions: Actinic keratoses are common, and there is a continuous spectr um of lesions that ranges from sun-damaged skin to squamous cell carcinoma in situ. Clinical distinguishing features may be difficult to delineate pre cisely. Counts of AK are commonly performed, but appear to be unreliable, e ven when performed by experienced dermatologists. joint discussion of discr epancies may enhance the reliability of these counts, although substantial variation remains. Research that relied on these counts must be reevaluated in light of the marked variation among expert observers. Future studies sh ould consider measures to assess and enhance reliability.