Background. The seven-point checklist (7PCL) has been recommended internationally for routine use in general practice to identify possible melanomas. We report the first formal validation in primary care of the 7PCL.
Data were obtained from the Molemate Trial (1) on patients presenting with a pigmented lesion in general practice. Data including the 7PCL items were collected on all lesions in the trial. Reference standard diagnoses were as follows: for referred lesions, histology or dermatology expert opinion; for non-referred lesions, clinical history, digital photograph, and SIAscopic image where available. 7PCL scores were calculated blinded to the reference diagnosis, and a case was defined as (1) a clinically significant lesion ; (2) melanoma.
1436 lesions were included in the analyses: 225 clinically significant cases including 36 melanomas and 1211 benign. For diagnosing clinically significant lesions there was a statistically significant difference between the performance of the Original and Weighted 7PCLs area under curve (AUC): 0.66 (0.62 to 0.70), 0.69 (95% CI 0.65 to 0.73), difference=0.03 (0.01 to 0.05, p<0.001). For the identification of melanoma, similar differences were found. Increasing the Weighted 7PCL’s cut-off score from recommended 3 to 4 improved detection of clinically significant lesions in primary care (sensitivity 73.3%, 67.1% to 79.0%; specificity 57.1%, 54.2% to 59.9%; PPV 24.1% (20.9% to 27.5%)), NPV 92.0% (89.8% to 93.9%)) while maintaining high sensitivity (91.7%, 77.5% to 98.3%) and moderate specificity (53.4%, 50.8% to 56.1%) for melanoma.
The Original and Weighted 7PCL both performed well in a primary care setting to identify clinically significant lesions as well as melanoma. The Weighted 7PCL, with a revised cut-off score of 4 from 3, performs slightly better than both the previous checklists and could be applied in general practice to support the recognition of clinically significant lesions and therefore the early identification of melanoma.