The Yearly Periodicity of Operative Upper Extremity Trauma: A Retrospective Study of "Trauma Season".

BACKGROUND: Upper extremity (UE) trauma requiring operative care increases during the summer and fall months, which the authors colloquially refer to as "trauma season." METHODS: CPT databases were queried for codes related to acute UE trauma at a single level-1 trauma center. Monthly CPT code volume was tabulated for 120 consecutive months and average monthly volume was calculated. Raw data were plotted as a time series and transformed as a ratio to the moving average. Autocorrelation was applied to the transformed data set to detect yearly periodicity. Multivariable modeling quantified the proportion of volume variability attributable to yearly periodicity. Subanalysis assessed presence and strength of periodicity in four age groups. RESULTS: A total of 11,084 CPT codes were included. Monthly trauma-related CPT volume was highest in July through October and lowest in December through February. Time-series analysis revealed yearly oscillation in addition to a growth trend. Autocorrelation revealed statistically significant positive and negative peaks at a lag of 12 and 6 months, respectively, confirming yearly periodicity. Multivariable modeling revealed R 2 attributable to periodicity of 0.53 ( P < 0.01). Periodicity was strongest in younger populations and weaker in older populations. R 2 was 0.44 for ages 0 to 17, 0.35 for ages 18 to 44, 0.26 for ages 45 to 64, and 0.11 for ages 65 and older. CONCLUSIONS: Operative UE trauma volumes peak in the summer and early fall and reach a winter nadir. Periodicity accounts for 53% of trauma volume variability. The authors' findings have implications for allocation of operative block time and personnel and expectation management over the course of the year.