Chronic Obstructive Pulmonary Disease (COPD) Metadata: Emergency Department (ED) Visits


ED visit data are from the Maine Health Data Organization (MHDO). Population data are from the U.S. Census Bureau.

Dates Available:

2001 – 2014, 2016, 2017

Geographic Resolution:

State, Public Health District, County, Town


The Maine EPHT program receives ED data annually, based on discharge date, from MHDO. Chronic Obstructive Pulmonary Disease (COPD) ED visits among Maine residents are analyzed, stratified by geographic resolution, age-group, and sex.

The dataset contains the following measures:

  1. Crude rate of ED visits for COPD per 10,000 population.
  2. Age-adjusted rate of ED visits for COPD per 10,000 population.
  3. Number of ED visits for COPD.


This data set supports efforts to improve public health in Maine and contributes to the U.S. CDC’s National Environmental Public Health Tracking (EPHT) Network. A key activity of participants in this network is to track and make available environmental health measures on state and national data portals. Measures derived from the data set described here can be used to compare COPD ED visits across the state, between groups of people, over time, and in relation to risk factors, exposures, and health outcomes.

The Maine Tracking Network, a member of the National EPHT Network, connects communities, public health professionals, policy makers, state agencies, and others to the data they need to monitor public health, respond to health concerns, prioritize resources for public health action, and evaluate prevention activities. Maine tracks certain health effects, exposures, and environmental hazards that have known relationships, as well as some health effects and environmental hazards that have suspected relationships. By making health and environmental data available through the Maine Tracking Network, more people have access to data they need to think critically and hypothesize about health outcomes and their relationships to conditions in the environment.

Supplemental Information:

Chronic Obstructive Pulmonary Disease (COPD) is defined as having a primary diagnosis of chronic bronchitis (ICD-9 CM Codes 490-491; ICD-10-CM J40-J42), emphysema (ICD-9 CM Code 492; ICD-10-CM J43), or chronic airway obstruction (ICD-9 CM Code 496; ICD-10-CM J44), or having a primary diagnosis of chronic obstructive asthma (ICD-9 CM Code 493.2) with ICD-9 CM Codes 490-492 or 496 listed as a secondary diagnosis.

The Maine EPHT program currently analyzes COPD ED visits by admission date only. The analysis de-duplicates patients to count one ED visit per patient per admission date.

Entity and Attribute Overview:

The dataset includes: admission year, geographic resolution, count, population, sex, age group, rate and 95% confidence intervals, age-adjusted rate and 95% confidence intervals.

Data Limitations:

  • Data represent the number of ED visits by admission date for COPD. The data do not represent the number of individual people seeking ED visits, nor the burden of disease in Maine.
  • Only Maine residents treated at Maine hospitals are included in the analysis; the total number of COPD ED visits, especially in areas served by hospitals in neighboring states or provinces, may be undercounted.
  • COPD ED data, by definition, do not include COPD-related events among individuals who do not receive medical care, are treated in outpatient settings, or die without being admitted to a hospital.
  • When comparing rates across geographic areas, a variety of non-environmental factors, including socio-demographic characteristics and access to medical care, can impact the likelihood of persons with COPD seeking treatment from an ED.
  • These data do not include patients served by Veterans Affairs, Indian Health Services, or patients who are institutionalized.

Access Constraints:

Publicly available data are suppressed in accordance with the Maine CDC Privacy Policy to protect confidentiality.

More Information:

  • To find more general information on this topic, see the COPD page of the Maine Tracking Network messaging portal.
  • To find more detailed information about the data source, see the MHDO metadata.
  • For specific definitions of terms and concepts see the Glossary.
  • For more information on MHDO, see the MHDO website.
  • To view data for other states and cities, visit the National Environmental Public Health Tracking Data Portal.

Suggested Citation for Data Displays:

Maine Center for Disease Control and Prevention, Maine Tracking Network. Asthma: Emergency Department Visits. Available online:  Accessed on [date accessed].