Background An essential aspect of an injury prevention process is surveillance, which quantifies and documents injury rates in populations of interest and enables monitoring of injury frequencies, rates and trends. To drive progress towards injury reduction goals, additional tools are needed. Statistical process control charts, a methodology that has not been previously applied to Army injury monitoring, capitalise on existing medical surveillance data to provide information to leadership about injury trends necessary for prevention planning and evaluation.
Methods Statistical process control Shewhart u-charts were created for 49 US Army installations using quarterly injury medical encounter rates, 2007–2015, for active duty soldiers obtained from the Defense Medical Surveillance System. Injuries were defined according to established military injury surveillance recommendations. Charts display control limits three standard deviations (SDs) above and below an installation-specific historical average rate determined using 28 data points, 2007–2013. Charts are available in Army strategic management dashboards.
Results From 2007 to 2015, Army injury rates ranged from 1254 to 1494 unique injuries per 1000 person-years. Installation injury rates ranged from 610 to 2312 injuries per 1000 person-years. Control charts identified four installations with injury rates exceeding the upper control limits at least once during 2014–2015, rates at three installations exceeded the lower control limit at least once and 42 installations had rates that fluctuated around the historical mean.
Conclusions Control charts can be used to drive progress towards injury reduction goals by indicating statistically significant increases and decreases in injury rates. Future applications to military subpopulations, other health outcome metrics and chart enhancements are suggested.
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The views expressed in this document are those of the authors and do not necessarily reflect the official policy of the Department of Defense, Department of Army, US Army Medical Department or the US Government.
Contributors AS is the lead author and accepts responsibility for the content as guarantor. She created the control charts within the dashboard system, maintains all data updates and drafted the Methods, Results, and Discussion. MC-C contributed explanations about the implications of control charts for improved military injury monitoring (Introduction, Discussion) and leads the referenced installation-specific injury reduction strategic initiative. BHJ supervised this work and made significant contributions to the data presentation and Discussion. All authors approve the final version of the manuscript.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.