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June 2018

Incorrect Denominator

JAMA Dermatol. 2018;154(6):739. doi:10.1001/jamadermatol.2018.2035

In the article titled “Accuracy of Skin Cancer Diagnosis by Physician Assistants Compared With Dermatologists in a Large Health Care System,” published online April 18, 2018, and in the May issue of JAMA Dermatology,1 an error occurred in Table 2. Percentages for 6 values were calculated using the wrong denominator: the number of visits during which a biopsy was performed was used instead of the number of all visits. In the outcomes section of the table, for melanoma diagnosed, the number (percentage) of all visits during which melanoma in situ was diagnosed should have been given as 98 visits (0.3%) for all clinicians, 40 (0.2%) for physician assistant (PA) only, and 58 (0.4%) for dermatologist only. Corresponding data for invasive melanoma diagnosed were 51 visits (0.2%) for all clinicians, 26 (0.2%) for PA only, and 25 (0.2%) for dermatologist only. These revisions do not affect the significance of the study findings or the conclusions. When the data for dermatologist only were compared with data for PA only, P = .04 for the diagnosis of melanoma in situ and P > .99 for invasive melanoma. Because of this error, 2 sentences in the text also require correction. In the Abstract’s Results section, the last sentence should have read: “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).” In the Visit Analyses subsection of the main text’s Results section, the third sentence should have read: “Screenings performed by dermatologists were more likely to result in a diagnosis of melanoma in situ (58 visits [0.4%] vs 40 [0.2%], P = .04), but not invasive melanomas (25 visits [0.2%] vs 26 [0.2%], P > .99) or nonmelanoma skin cancer (993 visits [6.1%] vs 1031 [6.1%], P = .98).” This article was corrected online.

Anderson  AM, Matsumoto  M, Saul  MI, Secrest  AM, Ferris  LK.  Accuracy of skin cancer diagnosis by physician assistants compared with dermatologists in a large health care system.  JAMA Dermatol. 2018;154(5):569-573. doi:10.1001/jamadermatol.2018.0212PubMedGoogle ScholarCrossref