Hospitalizations for Crohn's Disease — United States, 2003–2013

Christopher A. Malarcher; Anne G. Wheaton, PhD; Yong Liu, MD; Sujay F. Greenlund; Suraj J. Greenlund; Hua Lu, MS; Janet B. Croft, PhD

Disclosures

Morbidity and Mortality Weekly Report. 2017;66(14):377-381. 

In This Article

Abstract and Introduction

Introduction

In 2009, an estimated 565,000 Americans had Crohn's disease,[1] an inflammatory bowel disorder that can affect any part of the gastrointestinal tract. Symptoms include persistent diarrhea, abdominal cramps and pain, constipation leading to bowel obstruction, and rectal bleeding.* Symptoms sometimes intensify in severity and require hospitalization and surgeries of the small intestine, colon, or rectum.[2] Hospital discharge data from the National Inpatient Sample (NIS) of the Healthcare Cost and Utilization Project (HCUP) were used to estimate U.S. hospitalizations for Crohn's disease as both the first-listed and any-listed§ discharge diagnosis and common surgical procedures during hospitalizations with Crohn's disease as first-listed diagnosis from 2003 to 2013, the most recent decade of data. Despite new therapies that were expected to improve remission and reduce hospitalizations, estimated numbers (and age-adjusted rates per 100,000 U.S. population) of hospitalizations for Crohn's disease as the first-listed diagnosis did not change significantly from 2003 to 2013. The proportion of these hospitalizations during which small bowel resection was performed decreased from 4.9% in 2003 to 3.9% in 2013 (p<0.05); however, colorectal resection and fistula repair rates remained stable. Hospital stays for any-listed Crohn's disease increased from >120,000 (44.2 per 100,000) in 2003 to >196,000 (59.7 per 100,000) in 2013 (p<0.05). Patient education initiatives should focus on increasing awareness of exacerbating factors and medication compliance to prevent hospitalizations.

NIS hospital discharge data, which were obtained from the Agency for Healthcare Research and Quality (AHRQ), represent an annual stratified sample of 7–8 million hospital records collected by 37–44 participating states from approximately 20% of U.S. community hospitals. Records are weighted for hospital characteristics as well as for patient diagnoses, age, and admission month, so that analyses can produce reliable national estimates. Because the NIS implemented a new systematic sampling design in 2012, revised sampling weights were used for all analyses. Crohn's disease was defined for a first-listed diagnosis field and for any of 15 diagnosis fields during 2003–2008 and 25 fields during 2009–2013 with International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) disease codes 555.0–555.9. For states, the number of hospitalizations in 2013 with any diagnosis of Crohn's disease was obtained using the online query tool** from 35 states participating in the State Inpatient Databases, HCUP, AHRQ. Denominators for all annual hospitalization rates by age, sex, and state were obtained from the U.S. Census intercensal estimates for 2003–2009†† and 2010–2013.§§ Direct age-adjustment to the projected 2000 U.S. population was performed using five age groups (<18, 18–44, 45–64, 65–84, and ≥85 years) to calculate age-adjusted hospitalization rates per 100,000 U.S. population and 95% confidence intervals (CIs). Because race/ethnicity was not reported for 26% of hospital records in 2003 and 6% in 2013, these analyses do not include estimates by race/ethnicity. The percentages of first-listed hospitalizations that included small bowel resection, colorectal resection, or fistula repair were also obtained from any of up to 15 procedure fields.¶¶ SAS-callable SUDAAN was used to account for the complex sampling design of NIS. For comparisons of rates from 2003 to 2013 and between males and females, statistical significance (p<0.05) was determined by the Z-test.

Hospitalization rates for any-listed diagnosis of Crohn's disease were two times higher than those for a first-listed diagnosis from 2003 to 2007 and three times higher from 2008 to 2013 (Figure 1). Potential reasons for the sharp increase in hospitalization rates from 2007 to 2008 are unknown; however, there were no changes in NIS methodology, states reporting data, or diagnosis codes at that time. Age-adjusted hospitalization rates were higher among females than among males for both first-listed and any-listed diagnosis of Crohn's disease (p<0.05).

Figure 1.

Age-adjusted* hospitalization rate (per 100,000 population) for a first-listed or any-listed diagnosis of Crohn's disease, by sex — National Inpatient Sample, United States, 2003–2013
*Age-adjusted to the 2000 projected U.S. population.
First-listed Crohn's disease diagnosis indicates that Crohn's disease was the principal reason for the hospitalization. Any-listed Crohn's disease diagnosis indicates that patients had Crohn's disease, but Crohn's disease was not necessarily the main reason they were being hospitalized.

From 2003 to 2013, there was no significant change in the estimated number of hospitalizations for Crohn's disease as a first-listed diagnosis; however the age-adjusted hospitalization rate for Crohn's disease as any-listed diagnosis increased 35.1% from 44.2 per 100,000 (120,209 hospitalizations) in 2003 to 59.7 per 100,000 (196,480 hospitalizations) in 2013 (Table). As a first-listed diagnosis, there was a significant increase in the hospitalization rate in 2013 relative to 2003 (+14.5%), only among males (p<0.05). In contrast, hospitalization rates for any-listed Crohn's disease increased from 2003 to 2013 for all groups defined by age and sex. In both 2003 and 2013, hospitalization rates for Crohn's disease as a first-listed diagnosis were higher among persons aged 18–44 years than among other age groups, whereas, hospitalization rates with any-listed Crohn's disease increased among successive age groups until ages 65–84 years.

Geographic variations were observed in tertiles of age-adjusted hospitalization rates with any-listed Crohn's disease in 2013 among participating HCUP states (Figure 2), with age-adjusted hospitalization rates per 100,000 ranging from 19.2 in Hawaii to 91.6 in Rhode Island. States with the lowest hospitalization rates were clustered in the Southwest and Rocky Mountain states.

Figure 2.

Age-adjusted* hospitalization rate (per 100,000 population) for any-listed diagnosis§ of Crohn's disease — State Inpatient Databases, 2013
*Age-adjusted to the 2000 projected U.S. population.
Estimates considered unstable if relative standard error >30%.
§Any-listed Crohn's disease diagnosis indicates that patients had Crohn's disease, but Crohn's disease was not necessarily the main reason they were being hospitalized.

Among hospitalizations for a first-listed diagnosis of Crohn's disease in 2013, 3.9% were for small bowel resection, 12.8% for colorectal resection, and 2.0% for fistula repair. The decline in the percentage of hospitalizations for small bowel resection from 2003 (4.9%) was significant (p<0.05), but the percentages of 2003 hospitalizations for colorectal resections (14.8%) or fistula repairs (1.8%) were similar to those in 2013.

*http://www.crohnscolitisfoundation.org/what-are-crohns-and-colitis/what-is-crohns-disease.
Hospitalizations or hospital stays refer to a patient being admitted to a hospital for one or more days.
§First-listed Crohn's disease diagnosis indicates that Crohn's disease was the principal reason for the hospitalization. Any-listed Crohn's disease diagnosis indicates that patients had Crohn's disease, but Crohn's disease was not necessarily the main reason they were being hospitalized.
https://www.hcup-us.ahrq.gov/db/nation/nis/NISIntroduction2012.pdf.
**https://www.hcup-us.ahrq.gov/sidoverview.jsp. A list of the HCUP Data Partners that contribute to HCUP is available at https://www.hcup-us.ahrq.gov/db/hcupdatapartners.jsp.
††Intercensal Estimates of the Resident Population by Sex and Age for the United States: April 1, 2000 to July 1, 2010. https://www2.census.gov/programs-surveys/popest/tables/2000-2010/intercensal/national/us-est00int-01.xls.
§§Annual Estimates of the Resident Population: April 1, 2010 to July 1, 2014. 2014 Population Estimates. https://factfinder.census.gov/faces/tableservices/jsf/pages/productview.xhtml?pid=PEP_2016_PEPANNRES&src=pt.
¶¶ICD-9-CM procedure codes: small bowel resection (45.61–45.63), colorectal resection (17.3, 45.71–45.79, 45.81–45.83, 48.40–48.49, 48.50–48.59, or 48.61–48.69), fistula repair (46.74, 46.76, 48.73, 48.93, 49.11, 49.12, 49.73, 57.83, 58.43, or 70.72–70.74).

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