Breast Reconstruction-Related Procedures in Korea Across the COVID-19 Pandemic: A Nationwide Interrupted Time-Series and Provider–Location Analysis, 2015–2024

Backgroundand Objectives: We examined long-term breast reconstruction-related procedure use, composition, and provider–location concentration in Korea. Materials and Methods: Monthly aggregate Health Insurance Review and Assessment Service (HIRA) statistics for N7140–N7153 from April 2015 to December 2024 were analyzed using segmented regression, March 2020 and May 2022 breakpoints, calendar-month indicators, and Newey–West standard errors. Supplementary analyses examined nonlinear trends, working days, temporary interruptions, and mastectomy volume. Results: The series comprised 96,988 procedure uses; the annual volume increased 44.9% during 2016–2024. The modeled March 2020 level change was −82.0 uses (95% confidence interval [CI], −118.9 to −45.0; p < 0.001), or 8.5% below the counterfactual. The quadratic-time estimate was −55.7 (95% CI, −91.4 to −19.9; p = 0.002); category-specific findings were less robust. No clear additional level change occurred in May 2022. In the July 2017–December 2024 analysis, the estimated March 2020 level change in reconstruction-related uses per 100 malignant total-mastectomy uses was −1.51 (95% CI, −7.62 to 4.59; p = 0.627). The corresponding exploratory immediate direct-to-implant (DTI) ratio change was +1.77 per 100 mastectomy uses (95% CI, 0.14 to 3.40; p = 0.033). The DTI share increased from 20.7% to 45.1% of all included uses, while the autologous share decreased from 20.2% to 7.0%. DTI provider activity was less concentrated than the other single-code categories across the tested scenarios; the autologous comparison was sensitive in hypothetical nonzero-assignment stress tests. Conclusions: Recorded use increased and shifted toward DTI. The overall procedure-use ratio showed no statistically clear change; this establishes neither equivalence nor that mastectomy volume explains the decline in reconstruction-related use. These aggregate data describe service use, not individual pathways, patient travel, or causal pandemic effects.