Original Research
Epidemiologic Patterns of Injuries Treated in Ambulatory Care Settings

https://doi.org/10.1016/j.annemergmed.2005.07.009Get rights and content

Study objective

Epidemiologic studies of injury morbidity have relied primarily on data from emergency departments (EDs) and hospital admissions. We seek to assess the incidences and characteristics of acute injuries treated at EDs and other ambulatory care settings.

Methods

Using data from the 2002 National Health Care Survey on initial visits for acute injuries to EDs, physician offices, and hospital outpatient departments, we estimated the frequencies and incidence rates of medically attended injury by patient characteristics and care setting.

Results

In the United States in 2002, 76 million nonfatal acute injuries received initial medical attention at EDs (46.2%), physician offices (47.8%), and outpatient departments (6.0%). The overall annual incidence rate of medically attended injury was 26.8 per 100 population (95% confidence interval 24.4 to 29.7). Falls accounted for 16.7% of all medically attended injuries. Injury patients who were black or uninsured were significantly more likely to visit EDs than other care settings for treatment. More than 2.4 million (3.2%) injury patients were admitted to hospitals, 96.6% of them through EDs.

Conclusion

Fewer than half of all medically attended acute injuries in the United States receive initial treatment in EDs. Injury severity and characteristics vary among care settings.

Introduction

Injuries remain a major source of morbidity and mortality in the United States. Unintentional injuries are the leading cause of death among US individuals aged 1 to 34 years and the fifth leading cause of death for all age groups combined.1 These deaths represent few injuries, with estimates of approximately 200 emergency department (ED) visits for every injury death.2, 3 The societal cost associated with injuries is also enormous; the Centers for Disease Control and Prevention (CDC) estimated that injuries accounted for approximately 10% of total US medical expenditures in 2000, with costs of more than $224 billion annually if rehabilitation and lost wages and productivity are included.1, 4 Almost one third of all productive years of life that are lost before age 65 result from injuries, a proportion greater than the combined years lost to heart disease, stroke, and cancer.2

The lack of comprehensive national data on injuries remains an obstacle in injury research, and statistics on nonfatal injuries vary widely. The 2002 National Health Interview Survey and a 2003 National Center for Health Statistics report estimated 23.7 million to 34.4 million medically attended injuries and poisonings,5, 6 whereas a 1999 Institute of Medicine report estimated 37 million injury-related visits to EDs alone.2 These discrepancies are due in large part to differences in data sources. A recent study from Greece suggested that national injury estimates are less accurate when based on population surveys than on medical records.7

Most epidemiologic studies of injury morbidity have been restricted to data from ED or inpatient records, only partially revealing the full burden of injuries in the United States. The Institute of Medicine report included little discussion of injuries treated in clinics or physician offices, and a recent review of available metrics for measuring the burden of injuries similarly neglected non-ED ambulatory settings.2, 8 CDC data suggest that there could be almost 3 times as many injury-related visits to clinics or physician offices compared with EDs,9 but these figures include visits for initial injuries and their long-term sequelae. To our knowledge, no study has examined the epidemiologic patterns of acute injuries by combining data from different ambulatory care settings.

The primary objectives of this study were to use medical record data to estimate the annual incidence of nonfatal medically attended injuries in the United States and to compare the characteristics of medically attended injuries treated in EDs, physician offices, and hospital outpatient departments in the United States. Our results should show the magnitude of injury as a public health problem and provide useful information for understanding variations in the epidemiologic patterns of injuries treated in different ambulatory care settings, knowledge important for future injury research.

Section snippets

Study Design and Setting

We conducted a cross-sectional analysis of initial visits for acute injuries to EDs, physician offices, and hospital outpatient departments in the United States using 2002 data from the National Hospital Ambulatory Medical Care Survey (NHAMCS) and National Ambulatory Medical Care Survey (NAMCS). These surveys are conducted annually by the CDC's National Center for Health Statistics and use multistage probability sampling to derive national estimates of patient visits to care sites in the Unites

Results

In 2002, in the United States, an estimated 76.0 million injuries were treated at EDs (46.2%), physician offices (47.8%), and hospital outpatient departments (6.0%), yielding an overall incidence rate of 26.8 per 100 population (95% CI 24.4 to 29.7; Table 1). Injuries accounted for 35.7% of all initial visits to EDs for acute problems in 2002, compared to 17.1% to physician offices and 21.9% to hospital outpatient departments. Age-specific annual rates of medically attended injuries ranged from

Limitations

An important caveat to the implications of our results is that they represent only injury patients who actually visited an ED, physician office, or hospital outpatient department. Some patients do not seek medical care, especially for mild injuries, so our study cannot estimate the true incidence of injuries. The NAMCS and NHAMCS also do not allow for identification of risk factors, because they provide no information about uninjured individuals. Perhaps more important to the interpretation of

Discussion

Research of nonfatal injuries has focused primarily on ED visits and hospital admissions, resulting in considerable underestimates of the magnitude of injury morbidity that exclude the large proportion of injuries treated in non-ED settings.2, 4, 16 The primary objective of this study was to use medical record data to generate a more accurate estimate of the incidence of acute injuries treated in the United States. By combining national data from the main types of ambulatory care settings, we

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    Supervising editor: Arthur L. Kellermann, MD, MPH

    Author contributions: GL conceived the study and obtained research funding. MEB obtained, managed, and analyzed the data. GL provided statistical advice. MEB drafted the manuscript, and both MEB and GL contributed substantially to its revision. MEB takes responsibility for the paper as a whole.

    Funding and support: This research was supported in part by grants R01 AA09963 and R01 AG013642 from the National Institutes of Health and by grant CCR302486 from the Centers for Disease Control and Prevention.

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