The volume-outcome relationship in free-flap reconstruction: A nationwide study based on the Clinical Database.

BACKGROUND: The association between successful reconstructive surgery with a free flap and hospital volume has not been well established. This study was designed to retrospectively analyze the outcome of free-flap surgery registered in a nationwide surgical registration system in Japan to clarify the relationship between free-flap survival and facilities' average annual number of free-flap surgeries. METHODS: We analyzed data from 19,482 free flaps performed during 2017-2020 at 407 facilities throughout Japan. After adjusting for sex, age, and disease classification that differ between the groups, we examined the differences in the flap survival rates among the different facilities in terms of the average number of free-flap surgeries performed annually. RESULTS: The total overall necrosis rate was 2.8%. Of all procedures, 14.9%, 12.9%, 33.4%, and 38.8% were performed at facilities with an average number of free-flap procedures <10, 10-19, 20-49, and ≥ 50 per year, respectively, and the respective rates of total necrosis were 6.0%, 3.8%, 2.1%, and 1.7%, respectively. The odds ratios and 95% confidence intervals of flap necrosis for facilities with ≥ 50 cases per year relative to those <10 were 2.70 (1.98-3.68) for nonbreast reconstruction cases and 5.72 (2.77-11.8) for breast reconstruction cases. CONCLUSION: This analysis of a nationwide plastic surgery database showed that free-flap surgeries in institutions with a low average annual number of free-flap surgeries had a higher risk of total necrosis. Measures should be taken to either aggregate cases into high-volume centers or improve management at low-volume centers.