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Proportion of Thick versus Thin Melanomas as a Benchmarking Tool
Calogero Pagliarello1, Serena Magi2, Laura Mazzoni2
1UO Multizonale Dermatologia, Ospedale "Santa Chiara", 38122 Trento, Italy.
Journal of Clinical Medicine
|December 10, 2021
Summary
Reducing unnecessary mole excisions (number-needed-to-excise, NNE) is key for melanoma diagnosis efficiency. A lower NNE and thick/thin ratio (TTR) indicate better diagnostic performance without increasing the risk of missing melanomas.
Area of Science:
- Dermatology
- Oncology
- Health Services Research
Background:
- The number-needed-to-excise (NNE) measures melanoma diagnostic efficiency by tracking benign moles removed per melanoma diagnosed.
- Concerns exist that lowering NNE may increase the proportion of thicker melanomas, potentially impacting patient prognosis and healthcare costs.
- Breslow thickness is a critical prognostic factor in melanoma, not captured by NNE alone.
Purpose of the Study:
- To compare diagnostic performance between two tertiary referral centers using NNE and the thick/thin ratio (TTR).
- To determine if a reduced NNE is associated with a higher TTR, indicating a greater proportion of thicker melanomas.
- To evaluate the combined utility of NNE and TTR for assessing melanoma diagnostic effectiveness and associated costs.
Main Methods:
- Retrospective analysis of 16,738 excised skin lesions diagnosed as melanoma or melanocytic nevus between 2002 and 2011.
- Calculation and comparison of NNE and TTR between the Parma Dermatology Unit and the IRCCS Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) Unit.
- Logistic regression analysis to identify factors predicting a higher TTR, including the diagnosing center.
Main Results:
- The IRST Unit had a mean NNE of 4.6, while the Parma Unit had an NNE of 10.6.
- No significant differences in mean or median Breslow thickness were observed between the centers.
- The Parma Unit had a significantly higher TTR (24%) compared to the IRST Unit (12%), indicating a greater proportion of thicker melanomas.
- The diagnosing center was the strongest predictor of melanoma thickness >1 mm (OR=1.8).
- While NNE decreased with age, TTR increased, but this increase was not significantly related to NNE reduction after adjusting for confounders.
Conclusions:
- Improved diagnostic performance can simultaneously reduce NNE and TTR, minimizing unnecessary excisions without compromising melanoma detection.
- Integrating TTR with NNE provides a more comprehensive assessment of melanoma diagnostic effectiveness.
- This combined metric aids in evaluating both overall costs and costs associated with unnecessary benign lesion excisions at dermatology centers.
