Resection Weight Formulas for Reduction Mammoplasty: A Systematic Review and Regression Analysis.

Purpose: Estimating resection weight for patients undergoing reduction mammoplasty (RM) informs surgical planning and outcomes. Existing formulas have limitations that make insurance coverage and accurate surgical planning challenging. We identified the most commonly used scales to evaluate their accuracy in estimating resection weight by applying them to a database of patients to compare calculated and actual resection weights.

Methods: A database search was conducted using combinations of relevant terms. A regression analysis was conducted using formulas with strong R2 values (0.72-0.93) on a cohort of 1128 RM patients at a single institution.

Results: A total of 570 articles were identified. Fourteen manuscripts (n = 2232 patients [3320 breasts]) were ultimately included for review. Data on incisional patterns, pedicle supply, and breast measurements, such as sternal notch to nipple distance (n = 8 [57.1%]) or nipple to inframammary fold distance (n = 5 [35.7%]), were recorded. R2 values in our cohort (>500 g, n = 891; <500 g, n = 237) were calculated via regression analyses with five formulas: Appel (0.391 vs 0.146), Boukovalas (0.3552 vs 0.043), Descamps (0.391 vs 0.238), Eder (0.328 vs 0.114), and Kocak (0.3283 vs R2 indeterminate).

Conclusions: Our analysis suggests that formulas reporting strong R2 values may have resulted from tailoring to surgeons' technique. Variation between cohorts is inevitable; however, we expect reliable results given our large sample. It is reasonable to conclude that existing formulas are not accurate representations of resection weights and thus are unreliable for surgical planning.