In studies of skin cancer, participants are often classified into risk groups based on self-reported history of sun exposure or skin characteristics. We sought to determine the reliability of self-reported skin characteristics among participants of a study to evaluate markers for nonmelanoma skin cancer (NMSC). Multiple questionnaires and screening protocols were administered over a 3-month period to individuals from three risk groups: existing sun damage on forearms but no visible actinic keratoses (n = 91), visible actinic keratoses (n = 38), and history of resected squamous cell skin cancer in the last 12 months (n = 35). We assessed consistency of risk group assignment between telephone screen and study dermatologist assignment, self-reported sun sensitivity (telephone recruitment form versus participant completed profile), and self-reported history of NMSC skin lesions (telephone recruitment form versus health history). There was substantial agreement between probable risk group and final assignment (κ = 0.76; 95% confidence interval, 0.65-0.85) and agreement did not differ by gender. Agreement for self-reported sun sensitivity was moderate (κ weighted = 0.46; 95% confidence interval, 0.36-0.56) with higher agreement for women. For self-reported NMSC lesion history between two interviews, 24 days apart, κ estimates ranged from 0.66 to 0.78 and were higher for women than men. Overall, there was evidence for substantial reproducibility related to risk group assignment and self-reported history of NMSC, with self-reported sun sensitivity being less reliable. In all comparisons, women had higher κ values than men. These results suggest that self-reported measures of skin cancer risk are reasonably reliable for use in screening subjects into studies.
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