Primary care clinicians' performance for detecting actinic keratoses and skin cancer

If skin cancer screening is to become widely adopted, its effectiveness depends on the ability of primary care clinicians to detect cutaneous malignancies.

To assess primary care clinicians' proficiency for detecting skin cancers and actinic keratoses in a clinic population.

A convenience sample of 190 white male patients aged 40 years or older presenting to a university-affiliated Veterans Affairs general internal medicine or dermatology clinic were included in the study. Each patient was independently examined by a primary care clinician and a dermatologist to measure interobserver agreement. We compared the ability of primary care clinicians to diagnose actinic keratoses and skin cancers using dermatologists' examinations as a pragmatic reference standard.

Agreement was moderate as to whether a patient had single actinic keratosis (kappa, 0.36; 95% confidence interval [CI], 0.22-0.50), multiple actinic keratoses (kappa, 0.48; 95% CI, 0.34-0.61), or skin cancer (kappa, 0.48; 95% CI, 0.34-0.62). Agreement decreased when individual lesions were the unit of analysis. When the patient was the unit of analysis, primary care clinicians identified the presence of skin cancer with a sensitivity of 57% (95% CI, 44%-68%), specificity of 88% (95% CI, 81%-93%), positive likelihood ratio of 4.9 (95% CI, 3.0-8.3), and negative likelihood ratio of 0.48 (95% CI, 0.35-0.63). When the lesion was the unit of analysis the sensitivity was 38% (95% CI, 29%-47%), the specificity was 95% (95% CI, 93%-96%), the positive likelihood ratio was 7.1 (95% CI, 4.8-10.3), and the negative likelihood ratio was 0.66 (95% CI, 0.56-0.75).

Examinations performed by primary care clinicians for diagnosing skin cancer lacked sensitivity. Without improved diagnostic skills, primary care clinicians' examinations may be ineffective as a screening test.