Burden of Gastrointestinal Disease in the United States

2012 Update

Anne F. Peery; Evan S. Dellon; Jennifer Lund; Seth D. Crockett; Christopher E. Mcgowan; William J. Bulsiewicz; Lisa M. Gangarosa; Michelle T. Thiny; Karyn Stizenberg; Douglas R. Morgan; Yehuda Ringel; Hannah P. Kim; Marco Dacosta Dibonaventura; Charlotte F. Carroll; Jeffery K. Allen; Suzanne F. Cook; Robert S. Sandler; Michael D. Kappelman; Nicholas J. Shaheen

Disclosures

Gastroenterology. 2012;143(5):1179-1187. 

In This Article

Patients and Methods

We compiled the most recently available statistics on GI symptoms, quality of life, outpatient diagnoses, hospitalizations, cost, cancer, mortality, and endoscopic utilization from a variety of publicly and privately held databases. We utilized limited data sets with no direct patient identifiers. Data use agreements were signed as necessary. The methods used to compile the data from the respective source database are detailed below.

Symptoms and Diagnoses

We tabulated the leading GI symptoms and physician GI diagnoses for outpatient clinic visits in the United States from the 2009 National Ambulatory Medical Care Survey (NAMCS). NAMCS is an annual national survey sponsored by the US Centers for Disease Control and Prevention to provide information about the use of ambulatory services by children and adults in the United States (http://www.cdc.gov/nchs/ahcd.htm).

NAMCS collects symptom data with abstraction forms and is based on patient-reported symptoms. We used the principal reason for the clinic visit in our analysis. We combined related symptoms and created a rank order list. For example, the category "gastrointestinal bleeding" includes "gastrointestinal bleeding," "blood in stool," and "vomiting blood."

NAMCS also collects physician diagnoses from pediatric and adult patient encounter forms categorized according to the International Classification of Diseases, 9th Revision (ICD-9). A maximum of three ICD-9 codes are reported. We used the primary diagnosis for the visit unless otherwise noted. We combined related diagnoses and created a rank order list. We excluded "special screening of malignant neoplasm of the colon" (V765.1, n ≈ 1.6 million visits) because the code does not represent a diagnosis.

Quality of Life

We report the impact of select GI diseases and symptoms on quality of life and work and activity impairment using the 2010 United States National Health and Wellness Survey (NHWS) (N = 75,000) (Kantar Health, New York, NY). The NHWS is an annual, cross-sectional study administered by a private company to generate data on health-related outcomes and patient health care attitudes in persons 18 years and older. The NHWS utilizes a self-administered, Internet-based questionnaire. All participants complete an in-depth demographic profile and give informed consent. The NHWS uses a stratified random sample procedure to generate statistics reflective of the demographic composition of the United States, based on the March 2009 Census Bureau Current Population Survey. The prevalence estimates of conditions in the NHWS are comparable with the National Health Interview Survey, National Health and Nutrition Examination Survey, and Medical Expenditure Panel Survey.[7 8 9]

The NHWS assesses health-related quality of life with the Medical Outcomes Study 12-item Short Form Survey Instrument[10] and work and activity impairment with the Work Productivity and Activity Impairment Questionnaire in persons 18 years of age and older. [11 12] We generated mean Short Form Survey mental and physical component scores. A lower score is associated with worse quality of life. We also generated activity and work impairment scores, which represent the percentage of health-related impairment in daily activities and work, respectively, in the past 7 days. A higher percentage is associated with greater impairment. Work impairment included only participants who were employed. Participants with select diseases were identified for these analyses with the question "have you ever been diagnosed with X disease?" Participants with select symptoms were identified with the question "have you ever experienced Y symptom?" Reference diseases and symptoms have been included for comparison. Participants identified as "no disease" denied any of greater than 100 listed diseases. Population norms for Mental and Physical Component Summary scores were derived from the scoring algorithm of the Short Form-12 version 2. Population norms for the overall work impairment and activity impairment were derived by taking the mean across the entire NHWS sample (for employed-only respondents and all respondents, respectively).

Hospitalizations

We compiled the most common inpatient gastroenterology and hepatology discharge diagnoses from the 2009 Nationwide Inpatient Sample (NIS) (http://www.hcup-us.ahrq.gov/nisoverview.jsp). NIS was developed as part of the Healthcare Cost and Utilization Project, a federal-state-industry partnership sponsored by the Agency for Healthcare Research and Quality. NIS contains data from approximately 8 million hospital stays each year in both the pediatric and adult population. NIS is the largest all-payer inpatient care database in the United States. The 2009 NIS contains all discharge data from 1050 hospitals located in 44 states, approximating a 20% stratified sample of United States community hospitals. The sampling frame for the 2009 NIS is a sample of hospitals that comprises approximately 95% of all hospital discharges in the United States.

We generated rank order lists of discharge diagnoses and procedures for all patients in all hospitals. The diagnoses and procedures were categorized according to ICD-9 codes. We identified gastroenterology and hepatology diagnoses from the top 100 discharge diagnoses. We combined related discharge diagnosis codes. We created a rank order list of principal discharge diagnoses. We repeated this process and created a rank order list of any discharge diagnosis.

Additionally, we identified ICD-9 codes for several important gastroenterology and hepatology diagnoses not captured among the top 100 discharge diagnoses (eg, inflammatory bowel disease) and created a separate table of summary statistics for these diagnoses. Our results include both children and adults.

We performed a separate query for each individual ICD-9 code (or group of codes) to acquire data on mean and median length of stay, median costs, aggregate charges, and deaths. We estimated the total hospital days per year for all persons with each diagnosis by multiplying the number of discharges by the mean length of stay. We performed a temporal analysis of the most common and select principal GI diagnoses to determine the change in discharges between 2000 and 2009.

Cancer

We tabulated GI cancer incidence, mortality, and 5-year survival from the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute (www.seer.cancer.gov). The SEER program is a collection of population-based registries from 18 geographic regions in the United States including 9 states, 5 metropolitan areas, and the Alaska Native Tumor Registry. The SEER program includes both children and adults and represents approximately 26% of the United States population. We used the most recent version of the SEER Program (April 2011), which includes survival data through 2007 and incidence data through 2008.

We gathered unadjusted GI cancer incidence and mortality rates (per 100,000). We estimated the annual number of incident cases and deaths using the unadjusted rates, stratified by gender and age and applied to the 2010 US census population. We gathered 5-year survival data and reported the proportion surviving 5 years after diagnosis and stratified by stage of disease at diagnosis.

Mortality

We tabulated the leading GI causes of death from the National Vital Statistics System (NVSS) (http://www.cdc.gov/nchs/data_access/Vitalstatsonline.htm). NVSS is sponsored by National Center for Health Statistics with the Centers for Disease Control and Prevention. NVSS maintains an annually updated, county-level, national mortality database of children and adults with causes of death collected and reported by state registries. Causes of death are derived from death certificates and are classified by ICD-10 code. The most recent data were available from 2009.

We generated a rank order list of the most common GI causes of death. We combined associated diagnoses to create a single, clinically meaningful entity. For example, ulcers includes ICD-10 codes for gastric ulcer (K25), duodenal ulcer (K26), peptic ulcer (K27), and gastrojejunal ulcer (K28). We calculated the crude rate per 100,000 by dividing the number of deaths listed as an underlying cause by the total US population in the United States in 2009 (306,272,395) and multiplied by 100,000. The denominator was derived from population statistics on the Centers for Disease Control and Prevention's Wide-ranging Online Data for Epidemiologic Research (WONDER) Web site (http://wonder.cdc.gov). We repeated the process and created a rank order list of deaths from selected liver diseases. Our results include both children and adults.

Endoscopic Utilization

We generated an estimate for the prevalence and cost of upper, lower, and biliary endoscopies in 2009 using the Thompson Reuters MarketScan commercial (Thompson Reuters, New York, NY), Medicare, and Medicaid databases. These databases contained de-identified, person-level health care claims data for all inpatient, outpatient, and pharmaceutical services for a selection of health plans. These databases included both pediatric and adult populations with the exception of Medicare. Our results include both children and adults. In our analyses limited to 2009, the total numbers of individuals in each database were 29 million, 2.7 million, and 3.5 million, respectively.

We used current procedural terminology (CPT) codes to identify all endoscopic procedures in 3 broad categories: upper (esophagogastroduodenoscopy [EGD], upper endoscopic ultrasound [EUS], and enteroscopy), lower (colonoscopy, flexible sigmoidoscopy, lower endoscopic ultrasound, pouch/stoma endoscopy), and biliary (endoscopic retrograde cholangiopancreatography [ERCP]). We estimated the number of procedures performed in the United States in 2009 by standardizing the number of procedures in each database to the actual age and gender distribution of the US population based on 2009 census data. We determined the costs of endoscopic procedures in the United States in 2009 by summing all outpatient expenditures from the day of the procedure standardized by age and gender. Inpatient endoscopic procedure costs could not be isolated from other hospital-associated costs and were excluded from this analysis. We performed subanalyses for common codes because the upper and lower endoscopy categories encompassed multiple procedures. The subanalyses included EGD (diagnostic EGD, CPT 43235; and EGD with biopsy, CPT 43239) and colonoscopy (colonoscopy with biopsy, CPT 45380; and colonoscopy with polypectomy, CPT 45385).

We examined time trends in procedure volume in the 3 broad categories detailed above (upper, lower, and biliary) from 2000 to 2009 in the Thompson Reuters MarketScan commercial database. We also examined time trends for procedures reimbursed by Medicare Part B from 2000 to 2010. Medicare Part B National Summary Data Files are available through the Centers for Medicare and Medicaid Services (http://www.cms.gov/). We used CPT codes to identify all endoscopic procedures in 5 categories: upper endoscopy, colonoscopy, endoscopic retrograde cholangiopancreatography, magnetic resonance cholangiopancreatography, and upper and lower endoscopic ultrasound. The total number of procedures performed was calculated for each category annually between 2000 and 2010.

We compiled indications for common GI endoscopic procedures between 2005 and 2010 from the Clinical Outcomes Research Initiative's (CORI) National Endoscopic Database. CORI is a consortium of 108 sites from 87 practices. These practices include an adult population from private practices, academic medical centers, and government agencies (eg, military and Veterans Affairs Health Services). Participating sites use a structured, computerized, report generator to process all endoscopic reports and comply with quality control requirements.

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