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Original Investigation
May 2018

Accuracy of Skin Cancer Diagnosis by Physician Assistants Compared With Dermatologists in a Large Health Care System

Author Affiliations
  • 1Medical student, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
  • 2Department of Dermatology, University of Pittsburgh, Pittsburgh, Pennsylvania
  • 3Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
  • 4Department of Dermatology, University of Utah, Salt Lake City
  • 5Department of Population Health Sciences, University of Utah, Salt Lake City
JAMA Dermatol. 2018;154(5):569-573. doi:10.1001/jamadermatol.2018.0212
Key Points

Question  Are physician assistants and dermatologists equally accurate in diagnosing skin cancer in patients undergoing screening?

Findings  In this medical record review of 33 647 skin cancer screening examinations in 20 270 unique patients, physician assistants needed to biopsy 39.4 pigmented lesions and dermatologists needed to biopsy 25.4 pigmented lesions to diagnose 1 case of melanoma. Patients screened by a physician assistant were significantly less likely than those screened by a dermatologist to be diagnosed with melanoma in situ.

Meaning  Compared with dermatologists, physician assistants have lower diagnostic accuracy for melanoma.


Importance  Physician assistants (PAs) are increasingly used in dermatology practices to diagnose skin cancers, although, to date, their diagnostic accuracy compared with board-certified dermatologists has not been well studied.

Objective  To compare diagnostic accuracy for skin cancer of PAs with that of dermatologists.

Design, Setting, and Participants  Medical record review of 33 647 skin cancer screening examinations in 20 270 unique patients who underwent screening at University of Pittsburgh Medical Center–affiliated dermatology offices from January 1, 2011, to December 31, 2015. International Classification of Diseases, Ninth Revision code V76.43 and International Classification of Diseases and Related Health Problems, Tenth Revision code Z12.83 were used to identify pathology reports from skin cancer screening examinations by dermatologists and PAs.

Exposure  Examination performed by a PA or dermatologist.

Main Outcomes and Measures  Number needed to biopsy (NNB) to diagnose skin cancer (nonmelanoma, invasive melanoma, or in situ melanoma).

Results  Of 20 270 unique patients, 12 722 (62.8%) were female, mean (SD) age at the first visit was 52.7 (17.4) years, and 19 515 patients (96.3%) self-reported their race/ethnicity as non-Hispanic white. To diagnose 1 case of skin cancer, the NNB was 3.9 for PAs and 3.3 for dermatologists (P < .001). Per diagnosed melanoma, the NNB was 39.4 for PAs and 25.4 for dermatologists (P = .007). Patients screened by a PA were significantly less likely than those screened by a dermatologist to be diagnosed with melanoma in situ (0.2% vs 0.4% of visits, P = .04), but differences were not significant for invasive melanoma (0.2% vs 0.2% of visits, P > .99) or nonmelanoma skin cancer (6.1% vs 6.1% of visits, P = .98).

Conclusions and Relevance  Compared with dermatologists, PAs performed more skin biopsies per case of skin cancer diagnosed and diagnosed fewer melanomas in situ, suggesting that the diagnostic accuracy of PAs may be lower than that of dermatologists. Although the availability of PAs may help increase access to care and reduce waiting times for appointments, these findings have important implications for the training, appropriate scope of practice, and supervision of PAs and other nonphysician practitioners in dermatology.