Primer for New Injury Epidemiologists

This is the first International Classification of Disease, Tenth Revision, Clinical Modification (ICD-10-CM) Toolkit developed by the Council of State and Territorial Epidemiologists (CSTE). The purpose of this toolkit is to standardize resources for injury surveillance, epidemiology, and prevention. Its goal is to serve as a resource for using ICD-10-CM coded hospitalization and emergency department (ED) visit data to track injury burden in health departments. The target users for this toolkit are applied state, tribal, local, and territorial (STLT) epidemiologists who are new in the field of injury surveillance, as well as seasoned STLT epidemiologists seeking guidance in conducting injury and drug overdose surveillance using ICD-10-CM coded discharge data.


CSTE ICD-10-CM Workgroups

The CSTE ICD-10-CM Transition Workgroup was convened in 2016 to coordinate the work of diverse jurisdictions and assure that lessons learned about data quality, sensitivity of the proposed case definitions, and value of new details in ICD-10-CM are shared effectively with all stakeholders in this change. This workgroup builds on the work done by the Centers for Disease Control and Prevention (CDC), Safe States Alliance, and CSTE prior to the availability of discharge datasets coded in ICD-10-CM. The general injury surveillance guidance presented in this toolkit reflects the recommendations of the ICD-10-CM Transition Workgroup for measuring general injury burden using ICD-10-CM coded hospitalization and ED visit data.


Recognizing the need to build cross jurisdictional consensus on ICD-10-CM based drug overdose indicator definitions in alignment with larger injury surveillance methods, the CSTE ICD-10-CM Drug Poisoning Indicators Workgroup was created in 2017 in partnership with CDC’s NCIPC and the CSTE’s Injury ICD-10-CM Transition Workgroup. The drug overdose surveillance guidance presented in this toolkit reflects the recommendations of the ICD-10-CM Drug Poisoning Indicators Workgroup for measuring drug overdose burden using ICD-10-CM coded hospitalization and ED visit data.


ICD-10-CM Transition Background

Effective October 1, 2015, the U.S. Department of Health and Human Services required health care organizations and providers covered by the Health Insurance Portability and Accountability Act (HIPAA), to use ICD‐10‐CM to report medical encounters when submitting electronic claims for administrative and financial transactions. Prior to October 1, 2015, the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD‐9‐CM) was used for coding medical encounters in the hospital setting, including hospitalizations, ED visits, or outpatient offices. The major transition from ICD‐9‐CM to ICD‐10‐CM has affected local, state, and national activities that use electronic claims files from hospitalizations and ED visits to conduct injury and violence surveillance.3 


General Injury Surveillance

Surveillance is one of the most important and primary public health activities, because it drives injury prevention and control. According to the Centers for Disease Control and Prevention (CDC), each year millions of people experience nonfatal injuries in the United States. Surveillance measures the magnitude of injury and overdose, determines the leading causes and types of injury and overdose, and identifies the population groups most affected by these conditions. Such information is fundamental to determining program and prevention priorities, evaluating the effectiveness of program activities, and identifying priority areas that need further investigation.


Drug Overdose Surveillance

In 2017, drug overdose was the leading cause of injury death in the United States.1 However, for every fatal drug overdose, there are multiple nonfatal drug overdoses representing the burden of this epidemic.4 Overdose morbidity surveillance using ICD-10-CM coded hospitalization and ED visit data are instrumental to understanding the burden of nonfatal overdose and the injury epidemiologist’s ability to fully characterize the drug overdose epidemic in the United States. These data are vital to guiding successful program implementation and evaluation.



ICD-10-CM Injury Surveillance Toolkit Data Sources: Medical Administrative Discharge Data

Acute care hospitals in nearly every jurisdiction compile electronic data on all hospital discharges, including hospitalizations and ED visits, and make a combined jurisdiction-wide data set available to public health agencies.5 Healthcare data are obtained from encounters within hospital and ED settings. Traditionally, healthcare discharge data are collected for primarily administrative purposes, such as obtaining reimbursement for hospital care hospitals, but are also used for tracking utilization, costs, and quality of healthcare by jurisdiction health departments, hospitals, and hospital associations. These data provide details on the quality of healthcare services, types of services delivered, and billing charges on hospitalizations and ED visits. Moreover, the data present opportunities to survey injuries, including drug overdoses. This toolkit distinguishes between two major types of discharge data that are coded using ICD-10-CM – hospitalizations and ED visits.


Hospitalization and ED visit discharge data systems provide the opportunity to capture information on the circumstances of the injury using external cause of injury codes to classify injury events by intent (e.g., unintentional, assault, intentional self-harm, undetermined) and mechanism (e.g., motor vehicle crash, fall, struck by/against, firearm, poisoning). Jurisdiction hospital discharge data systems provide one of the best available data sources on external cause of injury for measuring the burden of nonfatal injury on society.1



Data are collected from hospitals for hospitalizations. These data are defined by the admission of a patient to a hospital for care by a medical professional. At least 90% of states maintain statewide, centralized, electronic databases of hospitalizations. The information collected varies from state to state, although many states use the standard uniform billing form (UB-04) as the basis for their hospitalization database. Others use only a subset of variables from the UB-04 for their databases, and a few collect additional variables. In ICD-10-CM, when an injury diagnosis is listed, an external cause of injury code should also be provided.5,6

ED Visits

Similarly, ED datasets collect information regarding individuals who present to an ED for care, including whether they are discharged from the ED directly or admitted to the hospital for further treatment. These data differ fundamentally from hospitalization data because they do not contain a Principal Diagnosis field (see Glossary of Terms/Abbreviations and Concepts for description of Principal Diagnosis field). 


Note that while many jurisdictions access their ED visit data through hospital discharge databases (the focus of this toolkit), many jurisdictions also or only have access to ED visit data via syndromic surveillance systems (SyS). SyS data may include discharge data coded in ICD-10-CM, however in many jurisdictions SyS data may also contain rich free text fields (e.g., chief complaint, triage notes) or incomplete data. This toolkit is designed for use with complete ED visit discharge datasets.6