The Burden of Asthma: Delineation of Acute Healthcare Utilization among Asthma Patients in Missouri, 2007- 2009

Research Article

Chronic Dis Int. 2016; 3(1): 1023.

The Burden of Asthma: Delineation of Acute Healthcare Utilization among Asthma Patients in Missouri, 2007- 2009

Homan S1,2*, Vantuinen M1,3, Gaddy PD1,4 and Yun S1,2

¹Division of Community and Public Health, Missouri Department of Health and Senior Services, USA

²Office of Epidemiology, Missouri Department of Health and Senior Services, USA

³Bureau of Health Care Analysis and Data Dissemination, Missouri Department of Health and Senior Services, USA

4Bureau of Cancer and Chronic Disease Control, Missouri Asthma Prevention and Control Program, USA

*Corresponding author: Sherri Homan, Division of Community and Public Health, Missouri Department of Health and Senior Services, Office of Epidemiology, Jefferson City, Missouri, USA

Received: July 16, 2016; Accepted: August 25, 2016; Published: August 26, 2016


Many people with asthma experience exacerbations. This study was conducted to describe the acute care utilization among patients with asthma in the state of Missouri and associated charges. Using the Patient Abstract System, records for Emergency Department (ED) visits; observation status; and hospital discharges with the principal diagnosis of asthma for a 3-year period (2007-2009) were linked for each patient using deterministic matching. The single record for each person was used in counting patients and in the analysis. There were a total of 115,299 acute care asthma visits for Missouri residents. The total number of ED visits, when ED visits plus hospitalization and ED visits plus observations were included was 106,443, or 20.1% higher than the 88,622 ED only visits to 73,162 total patients. Children aged = 17 comprised 24.1% of Missouri’s population, but represented more than 41.9% of patients using these services. Of the 68,792 patients with an ED visit, 75.8% had a single visit during the 3 years. Of those with = 2 ED visits (n=16,644), African Americans (11.17 per 1,000, 95% CI 11.03-11.31) and children aged 0-4 (10.19 per 1,000, 95% CI 10.00-10.37) had the highest rates. Overall, 26.1% of the total patients were hospitalized, accounting for > 70% of the total $394.8 million. MO Health Net (Medicaid) was the most frequent expected pay source. Uncontrolled asthma places a heavier toll on emergency departments than previously published. Increased application of evidence-based asthma control care and exacerbation prevention strategies may substantially improve health and reduce costs.

Keywords: Asthma, Morbidity, Health services, Medical record linkage, Hospitalization


AMA: Against medical advice; BRFSS: Behavioral risk factor surveillance system; CDC: Centers for disease control and prevention; DHSS: Missouri department of health and senior services; ED: Emergency department; ICD-9-CM: International classification of diseases, ninth revision, Clinical modification; LOS: Length of stay; PAS: Patient abstract system; RSMo: Missouri revised statute; SSN: Social security number


Asthma, a chronic inflammatory respiratory condition, may lead to disability and adversely affect quality of life when not well controlled. Nationally, approximately 26.2 million adults [1] and children [2] and more than 600,000 people in Missouri have the condition. From 2001 to 2010, the prevalence of asthma in the US increased 1.4% per year among children aged = 17 and 2.1% among adults aged = 18 [3]. The increase was even greater among African- Americans and Hispanics, 3.2% per year. However, a recent study has found a decline in the prevalence of childhood asthma and a lessening in the white - black disparity in 2013 [4]. Improved scientific understanding of the disease has lead to substantial improvements in care [5]. Yet, many people are not well controlled and experience exacerbations that require emergency care or hospitalization.

While all health services have a cost, Emergency Department (ED) visits and hospitalizations are among the most costly. In the US, there were approximately 1.8 million ED visits (2011) and 439,000 hospitalizations for asthma (2010) [6,7]. In Missouri, there were 29,616 asthma ED only visits and 6,525 hospitalizations in 2013 [8,9]. Encounter data such as these are useful, but do not provide the number of individuals utilizing emergency services due to asthma or accurately reflect the total burden on emergency departments since patients seen in the ED and then are admitted, are often only captured in the hospitalization data. This was the case for about 50% of the 36 states participating in the National Asthma Prevention and Control Program in 2008-2009 [10] and this method of data capture continues for many of the states including Missouri. This study was conducted to determine the number of people with asthma in Missouri provided care in emergency departments, the populations with high utilization of acute health services, the percent with such serious asthma as to require hospitalization, and expected payment sources.


Data source

The Missouri Department of Health and Senior Services (DHSS) is the custodian of acute care hospital, ED, and ambulatory surgery center data for the State of Missouri. The Patient Abstract System (PAS), established in 1993 by state statute (192.665 - 192.667RSMo), contains patient abstract records data for Missouri residents [11]. This system provides multiple elements, including demographics; ED visits; invasive and certain diagnostic procedures; admission, observation stays, and hospital discharge information; pay sources; and charges. Prior to data analysis, the DHSS Institutional Review Board reviewed the study and determined it to be exempt.

Identifying asthma patients

In the US, during the study period, the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) was the system used to classify and assign codes to health conditions. The ICD-9 code for asthma with any extension (493.xx) was used to select records [12]. Records for ED visits, observation-room discharges, and hospital discharges with the principal diagnosis of asthma for 2007- 2009 were selected from the PAS. Outpatient surgery and ‘Other Outpatient’ records were excluded.

Data analysis

Although patients do not have identifiers that are the same within and across institutions, records were identified for each patient by using deterministic matching in multiple passes that used first and last name, date of birth, sex, race, Social Security Number (SSN), hospital identifier, and medical record number in various combinations. If SSN, first and last names matched, the records were linked; however, if SSN was missing, an iterative deterministic matching process was performed requiring an exact match on one of several passes but not on all possible identifiers. Finally, potential matches were manually reviewed and linked if matches were determined. Records for a patient were assigned the same identification number. Characteristics of patients included race, ethnicity, and assignment to age groups using the earliest patient’s record. The proportion for each characteristic was compared to the 2008 Missouri population to assess disproportional use [13]. Further, in counting patients, one record for each person was selected giving priority to the ED records; if a patient had no ED record, than an admission record was selected, and if neither of these were present, then an observation record was selected. Insurance coverage compared the proportion of asthma patients that were selfpay or not charged to the Missouri population with no insurance coverage [14]. Charges for ED visits, hospitalizations, and observation visits were summed and the expected pay sources assessed. Data were analyzed using SAS 9.3 (SAS Institute, Inc. Cary, NC).

Patients with at least 1 ED visit were grouped into two categories: single exacerbation requiring 1 ED visit and multiple exacerbations requiring = 2 ED visits. Rates and 95% confidence intervals were calculated to compare population groups. The rate was calculated using the total number of ED visits for the 3 years (numerator) divided by the sum of Missouri’s population for the 3 year time period (denominator), then multiplied by 1,000. Hospitalization, Length Of Stay (LOS), procedures, and anoxia were included as indicators of episode severity and risk for future exacerbations or fatality. Deaths during the study period were also reviewed.

Identifying health care visits

Five categories of records were created: ED visit only, ED visit with hospitalization, ED visit with observation stay, Observation stay only and Hospitalization only. To obtain the number of people for each category, records were linked to create a single record per person and the single record was used in counting patients. To determine the total number of patients hospitalized, the ED visit with observation group was also linked to hospitalization records to determine the number whose status was changed to an inpatient.

Results and Discussion

Health care visits: ED visits, hospitalizations and observations

There were a total of 115,299 records with a principal diagnosis of asthma for the 3-year period (Figure 1). A total of 73,162 patients accounted for these visits (Table 1). Compared to the 2008 population, the age distribution for asthma patients suggests that the younger children were over represented, particularly children age 0 to 4 accounted for 17.6% of the asthma health care visits, but made up only 6.6% of the population. African Americans were also over represented, accounting for about 33.9% of the visits while comprising only about 12.1% of the population. Those 65 and older were under represented accounting for 7.6% of asthma health care visits but made up 13.7% of the population. Overall, children and adolescents = 17 years of age accounted for 41.9% of the health care visits for asthma but comprised 24.1% of the population. There was also a slight excess of health care visits among females (56.2%) compared to their population size (51.1%). The number of health care visits for asthma was evenly distributed across the 3 years, but the number of individuals decreased substantially from 2007 to 2009 (27.9%). The majority of asthma patients (84.0%) had a visit in just one of the years, and just slightly > 3% had visits each year.