Background Road traffic deaths (RTDs) remain the 9th most common cause of mortality in South Korea despite their decreasing trends in high-income countries. In 2010 and 2011, the Korean government deregulated the process for obtaining a driving licence, and there has been significant concern that such deregulation of the driving licence policy could reduce road safety. This study aimed to explore the effects of the deregulation of driving licence policy on road safety by examining the incidence of road traffic collisions (RTCs), road traffic injuries (RTIs) and RTDs.

Methods The monthly incidence of RTCs, RTIs and RTDs was generated by using numbers of RTCs, RTIs and RTDs as numerators and numbers of registered vehicles as denominators. Changes in incidence since the deregulation implementation in February 2010 (phase I) and June 2011 (phase II) were evaluated via interrupted time-series analysis.

Results The second deregulation phase demonstrated significant changes in numbers of RTCs and RTIs: numbers of RTCs and RTIs decreased until they began to increase in November 2011. Since then, the monthly incidence of RTCs and RTIs have increased by 133.5 and 123.8 per 100 000 vehicles per month, respectively (p<0.05). RTD secular trends began to increase consecutively at rates of 0.024 (June 2010), 0.018 (between July 2010 and June 2011) and 0.273 (July 2011 onward) per 100 000 vehicles per month. Over the entire study period, the RTD incidence rate increased by 0.018 deaths per month on average subsequent to the first deregulation phase (p<0.05).

Conclusions The deregulation policies that simplified the driving licence process were associated with increased incidence of RTCs, RTIs and RTDs in Korea.