Low back pain in the United States: incidence and risk factors for presentation in the emergency setting

Abstract

Low back pain is prevalent in the United States. At the present time, no large longitudinal study is available characterizing the incidence of this condition in the US population or identifying potential risk factors for its development. To characterize the incidence of acute low back pain requiring medical evaluation in the emergency department and establish risk factors for its development. Cross-sectional study. United States population estimates. Incidence rate ratios were calculated to determine the influence of age, sex, and race on the development of low back pain requiring emergent medical evaluation. The National Electronic Injury Surveillance System was queried for all cases of low back pain presenting to emergency departments between 2004 and 2008. Incidence rate ratios were then calculated with respect to age, sex, and race. The chi-square statistic was used to identify statistically significant differences in the incidence of low back pain requiring emergent medical evaluation between subgroups. An estimated 2.06 million episodes of low back pain occurred among a population at risk of over 1.48 billion person-years for an incidence rate of 1.39 per 1,000 person-years in the United States. Low back pain accounted for 3.15% of all emergency visits. Injuries sustained at home (65%) accounted for most patients presenting with low back pain. Low back pain demonstrates a bimodal distribution with peaks between 25 and 29 years of age (2.58/1,000 person-years) and 95 to 99 years of age (1.47/1,000) without differentiation by underlying etiology. When compared with females, males showed no significant differences in the rates of low back pain. However, when analyzed by 5-year age group, males aged 10 to 49 years and females aged 65 to 94 years had increased risk of low back pain than their opposite sex counterparts. When compared with Asian race, patients of black and white race were found to have significantly higher rates of low back pain. Older patients were found to be at a greater risk of hospital admission for low back pain. Age, sex, and race are significant risk factors for the development of low back pain necessitating treatment in an emergency department.