Japan's Nationwide Trend in Scoliosis Surgery from 2014 to 2022; from a Country with a Declining Underage Population.

Introduction: Japan is experiencing a significant demographic shift characterized by a declining birthrate and an aging population. A previous report indicated a discrepancy between the trends in the number of spinal surgeries performed for minors and the overall population dynamics. Japan has the National Database of Health Insurance Claims and Specific Health Checkups (NDB), which contains 99.9% of public health insurance claims from hospitals and 97.9% from clinics. This study aimed to investigate the annual number of scoliosis surgeries performed on patients aged 19 years in Japan, evaluate trends in relation to the overall population dynamics, and examine potential factors contributing to the observed changes.

Methods: This retrospective study utilized NDB and census data. Scoliosis surgeries were identified using K-codes specific to the procedure. Population data were estimated using census and national birth records released by the Japan Cabinet Office. The number of surgeries per 100,000 minors was calculated, and trends were analyzed from 2014 to 2021.

Results: The number of scoliosis surgeries for patients under 19 years old increased from 1,282 in 2014 to 1,850 in 2021, despite a decrease in the number of patients under 19 years old. The rate of scoliosis surgeries per 100,000 minors increased from 5.6 in 2014 to 9.1 in 2021, whereas other spinal fusion procedures for minors did not show significant changes during the same period.

Conclusions: Despite a decline in the underage population, the number of scoliosis surgeries among minors has paradoxically increased in Japan. Improvements in screening tools and the April 2016 change in the law mandating a full motor examination, including scoliosis testing, may have affected this trend. Further follow-up studies are required.