Chapter 16: Functional Intestinal Disorders

The Burden of Digestive Diseases in the United States

James E. Everhart, M.D., M.P.H.

Included in this chapter are separate entries on chronic constipation and irritable bowel syndrome (IBS). Other functional conditions that were either too uncommon or too nonspecific were functional diarrhea, neurogenic bowel and megacolon not elsewhere described, anal spasm, and other specified and unspecified functional intestinal disorders. These are included in the section All Functional Intestinal Disorders.

CHRONIC CONSTIPATION

In 2004, constipation was frequently noted at ambulatory care visits either as a first-listed diagnosis (3.1 million visits) or all-listed diagnoses (6.3 million visits) (Table 1), which made it the second most common ambulatory care diagnosis, after GERD. Persons under age 15 years had the highest number of visits for chronic constipation and nearly as great a rate as persons age 65 years and older. The number of ambulatory care visits for the younger age group was equal to that of intestinal infections (Chapter 2). Chronic constipation and GI infections were the two most common reasons for ambulatory care visits among children. Rates of visits with a chronic constipation diagnosis were also higher for blacks and for females. Hospitalizations with chronic constipation were uncommon, with first-listed diagnoses only 1–2 percent of ambulatory care visits. All-listed diagnoses of chronic constipation were more common—about one-tenth the rate of all-listed ambulatory care diagnoses. After many years of stable rates of medical care statistics for chronic constipation, there was a surge in both ambulatory medical care visits and hospitalizations between 1992 and 2004 (Figure 1), with more than a doubling of rates of ambulatory care diagnoses and nearly a fourfold increase in rates of hospital discharge diagnoses. The rate of ambulatory visits began to increase at least as early as 1985, when there were approximately 500 per 100,000 population.10

Mortality from chronic constipation is, of course, rare (Table 2). Nevertheless, in keeping with the increase in medical care, there was an increase in constipation as either underlying cause or underlying or other cause between 1989 and 2004 (Figure 2).

According to the Verispan database of retail pharmacy prescriptions (Appendix 2), in 2004, nearly half of all medications prescribed for chronic constipation were for the laxative polyethylene glycol (Table 3). Tegaserod (Zelnorm®), a medication for women with irritable bowel syndrome and constipation, was not as commonly prescribed, but was nearly as costly. Other medications were primarily stool softeners or motility agents. These data did not capture the very large number of nonprescription medications purchased for constipation.

IRRITABLE BOWEL SYNDROME

In 2004, there were 3 million ambulatory care visits with IBS noted as a diagnosis, and slightly more than half were first-listed diagnoses (Table 4). Unlike constipation, which was common among children, rates of visits with IBS increased with age only in later adulthood. Whites had more than twice the age-adjusted rate of visits as blacks. The rate of visits among females was more than 4 times that of males—the largest sex difference for any digestive disease. IBS was rarely noted as first-listed diagnosis on hospital discharge, but was much more commonly coded as a secondary diagnosis. The age, race, and sex patterns for all-listed discharge diagnosis were similar to ambulatory care diagnoses.

Age-adjusted rates of ambulatory care visits with an IBS diagnosis fell by about 20 percent between 1992–1993 and 2003–2005 (Figure 3), although the rate in the latest period was similar to rates in 1981, 1982, and 1985.11 In contrast, rates of hospital discharges with a diagnosis of IBS fell in the mid-1980s, leveled off through the mid-1990s, and then increased by 81 percent between 1999 and 2004. IBS as underlying or contributing cause of death was exceedingly rare (Table 5), and trend data were not meaningful (Figure 4).

According to the Verispan database of retail pharmacies, in 2004, tegaserod (Zelnorm®) contributed much to the cost of IBS and was the third most widely prescribed drug (Table 6). The anticholinergic drugs hyoscyamine and dicyclomine were the most commonly prescribed drugs.

ALL FUNCTIONAL INTESTINAL DISORDERS

As a group of conditions, functional disorders were common reasons for outpatient visits, such that there were estimated to be more than 11 million ambulatory care visits noting these diagnoses in 2004 (Table 7), or about 4 visits per every 100 persons in the United States. Eighty percent of these visits were for either chronic constipation or IBS. Hospitalizations for functional disorders were uncommon, but they did commonly appear as an all-listed diagnoses. Recent increases in diagnoses with a mention of functional disorders on ambulatory care visits and hospital discharge were almost entirely due to increased rates of diagnoses of constipation (Figure 5). Chronic constipation and IBS accounted for 73.5 percent of these diagnoses. Functional disorders were coded as an underlying cause of death for 423 persons in 2004, and listed as a contributing cause for 1,766 persons (Table 8). The death rate with mention of functional intestinal conditions was stable from 1979 to 1999, when the change to ICD-10 coding resulted in a 19 percent increase that was likely a coding artifact (Figure 6).

According to the Verispan database of retail pharmacies, in 2004, there were estimated to be more than 13 million prescriptions filled at retail pharmacies at a cost of nearly three-quarters of a billion dollars (Table 9). Nearly one-third of this cost was for tegaserod (Zelnorm®). Other agents were primarily for pain, including several acid-blocking agents, or for constipation.

References

Table 1. Chronic Constipation: Number and Age-Adjusted Rates of Ambulatory Care Visits and Hospital Discharges With First-Listed and All-Listed Diagnoses by Age, Race, and Sex in the United States, 2004

Source: National Ambulatory Medical Care Survey (NAMCS) and National Hospital Ambulatory Medical Care Survey (NHAMCS) (3-year average, 2003–2005), and Healthcare Cost and Utilization Project Nationwide Inpatient Sample (HCUP NIS)

Demographic Characteristics Ambulatory Care Visits First-Listed Diagnosis Number in Thousands Ambulatory Care Visits First-Listed Diagnosis Rate per 100,000 Ambulatory Care Visits All-Listed Diagnosis Number in Thousands Ambulatory Care Visits All-Listed Diagnosis Rate per 100,000 Hospital Discharges First-Listed Diagnosis Number in Thousands Hospital Discharges First-Listed Diagnosis Rate per 100,000 Hospital Discharges All-Listed Diagnosis Number in Thousands Hospital Discharges All-Listed Diagnosis Rate per 100,000
AGE (Years)
Under 15
1,175 1,933 2,127 3,497 5 8 32 53
AGE (Years)
15–44
601 478 1,397 1,110 6 5 106 84
AGE (Years)
45–64
492 696 1,112 1,572 8 11 164 231
AGE (Years)
65+
880 2,423 1,671 4,599 18 50 399 1,097
Race
White
2,582 1,064 5,057 2,100 28 11 534 209
Race
Black
430 1,011 990 2,620 5 15 98 322
Sex
Female
1,955 1,267 4,050 2,655 23 14 434 260
Sex
Male
1,194 866 2,256 1,657 14 11 266 206
Total 3,149 1,072 6,306 2,148 37 13 700 238

Figure 1. Chronic Constipation: Age-Adjusted Rates of Ambulatory Care Visits and Hospital Discharges With All–Listed Diagnoses in the United States, 1979–2004

The rate of ambulatory care visits over time (age-adjusted to the 2000 U.S. population) is shown by 3-year periods (except for the first period which is 2 years), between 1992 and 2005 (beginning with 1992–1993 and ending with 2003–2005). After many years of stable rates of medical care for chronic constipation, there was a surge in both ambulatory medical care visits and hospitalizations between 1992 and 2004. Ambulatory care visits per 100,000 increased from 876 in 1992-1993 to 2,151 in 2003-2005. The hospitalization rate per 100,000 was 36.1 in 1979 and remained stable through 1992, after which it increased to 154 in 2004.
Source: National Ambulatory Medical Care Survey (NAMCS) and National Hospital Ambulatory Medical Care Survey (NHAMCS) (averages 1992–1993, 1994–1996, 1997–1999, 2000–2002, 2003–2005), and National Hospital Discharge Survey (NHDS)

Table 2. Chronic Constipation: Number and Age-Adjusted Rates of Deaths and Years of Potential Life Lost (to Age 75) by Age, Race, and Sex in the United States, 2004

Source: Vital Statistics of the United States

Demographic Characteristics Underlying Cause Number of Deaths Underlying Cause Rate per 100,000 Underlying Cause Years of Potential Life Lost in Thousands Underlying or Other Cause Number of Deaths Underlying or Other Cause Rate per 100,000
AGE (Years)
Under 15
3 0.0 0.2 6 0.0
AGE (Years)
15–44
11 0.0 0.5 22 0.0
AGE (Years)
45–64
10 0.0 0.2 54 0.1
AGE (Years)
65+
113 0.3 0.1 500 1.4
Race
White
129 0.1 0.8 527 0.2
Race
Black
7 0.0 0.1 48 0.1
Sex
Female
98 0.1 0.4 381 0.3
Sex
Male
39 0.0 0.5 201 0.1
Total 137 0.0 0.9 582 0.2

Figure 2. Chronic Constipation: Age-Adjusted Rates of Death in the United States, 1979–2004

There was an increase in mortality rates as either underlying cause or underlying or other cause between 1989 and 2004. Underlying-cause mortality per 100,000 was 0.01 in 1979, 0.02 in 1989, and rose to 0.04 in 2004. All-cause mortality per 100,000 was 0.06 in 1979, 0.08 in 1989, and rose to 0.19 in 2004.
Source: Vital Statistics of the United States

Table 3. Chronic Constipation: Costliest Prescriptions

Source: Verispan

DRUG Prescription (#) Prescription Retail Cost Cost
Polyethylene Glycol 3350 2,462,873 46.0% $78,006,220 43.8%
Tegaserod 487,989 9.1 62,696,997 35.2
Lactulose 1,234,865 23.1 29,190,969 16.4
Docusate® 1,087,397 20.3 7,481,476 4.2
Methylcellulose 13,221 0.2 219,099 0.1
Magnesium Hydroxide 40,991 0.8 176,097 0.1
Psyllium 10,634 0.2 172,225 0.1
Senna® 4,085 0.1 139,618 0.1
Bisacodyl 10,271 0.2 57,569 0.0
Malt Extract 535 0.0 37,774 0.0
Other 3,432 0.0 66,635 0.0
TOTAL 5,356,293 100.0% $178,244,679 100.0%

Table 4. Irritable Bowel Syndrome: Number and Age-Adjusted Rates of Ambulatory Care Visits and Hospital Discharges With First-Listed and All-Listed Diagnoses by Age, Race, and Sex in the United States, 2004

Source: National Ambulatory Medical Care Survey (NAMCS) and National Hospital Ambulatory Medical Care Survey (NHAMCS) (3-year average, 2003–2005), and Healthcare Cost and Utilization Project Nationwide Inpatient Sample (HCUP NIS)

Demographic Characteristics Ambulatory Care Visits First-Listed Diagnosis Number in Thousands Ambulatory Care Visits First-Listed Diagnosis Rate per 100,000 Ambulatory Care Visits All-Listed Diagnosis Number in Thousands Ambulatory Care Visits All-Listed Diagnosis Rate per 100,000 Hospital Discharges First-Listed Diagnosis Number in Thousands Hospital Discharges First-Listed Diagnosis Rate per 100,000 Hospital Discharges All-Listed Diagnosis Number in Thousands Hospital Discharges All-Listed Diagnosis Rate per 100,000
AGE (Years)
Under 15
0 1 1 2
AGE (Years)
15–44
724 575 1,169 929 8 6 61 48
AGE (Years)
45–64
363 514 979 1,384 5 7 73 103
AGE (Years)
65+
469 1,290 792 2,179 4 11 77 213
Race
White
1,459 593 2,803 1,138 15 6 180 72
Race
Black
212 534 1 4 12 36
Sex
Female
1,322 867 2,531 1,649 14 9 177 112
Sex
Male
283 201 523 373 4 2 35 26
Total 1,605 547 3,054 1,040 18 6 212 72

Figure 3. Irritable Bowel Syndrome: Age-Adjusted Rates of Ambulatory Care Visits and Hospital Discharges With All–Listed Diagnoses in the United States, 1979–2004

The rate of ambulatory care visits over time (age-adjusted to the 2000 U.S. population) is shown by 3-year periods (except for the first period which is 2 years), between 1992 and 2005 (beginning with 1992–1993 and ending with 2003–2005). Ambulatory care visits per 100,000 fell from 1,240 in 1992-1993 to 1,032 in 2003-2005. In contrast, rates of hospital discharges fell in the mid-1980s, leveled off through the mid-1990s, and then increased between 1999 and 2004. The hospitalization rate per 100,000 was 91.2 in 1979 and remained stable through 1983, after which it decreased to 31.6 in 1990 and remained stable until 1999, and from there it increased to 54.8 in 2004.
Source: National Ambulatory Medical Care Survey (NAMCS) and National Hospital Ambulatory Medical Care Survey (NHAMCS) (averages 1992–1993, 1994–1996, 1997–1999, 2000–2002, 2003–2005), and National Hospital Discharge Survey (NHDS)

Table 5. Irritable Bowel Syndrome: Number and Age-Adjusted Rates of Deaths and Years of Potential Life Lost (to Age 75) by Age, Race, and Sex in the United States, 2004

Source: Vital Statistics of the United States

Demographic Characteristics Underlying Cause Number of Deaths Underlying Cause Rate per 100,000 Underlying Cause Years of Potential Life Lost in Thousands Underlying or Other Cause Number of Deaths Underlying or Other Cause Rate per 100,000
AGE (Years)
Under 15
AGE (Years)
15–44
7 0.0
AGE (Years)
45–64
1 0.0 0.0 21 0.0
AGE (Years)
65+
19 0.1 0.0 188 0.5
Race
White
19 0.0 0.0 210 0.1
Race
Black
1 0.0 0.0 5 0.0
Sex
Female
16 0.0 0.0 164 0.1
Sex
Male
4 0.0 0.0 52 0.0
Total 20 0.0 0.0 216 0.1

Figure 4. Irritable Bowel Syndrome: Age-Adjusted Rates of Death in the United States, 1979–2004

IBS as underlying or contributing cause of death was exceedingly rare and trend data were not meaningful.
Source: Vital Statistics of the United States

Table 6. Irritable Bowel Syndrome: Costliest Prescriptions

Source: Verispan

DRUG Prescription (#) Prescription Retail Cost Cost
Tegaserod 1,101,880 18.6% $171,155,138 58.1%
Hyoscyamine 1,574,929 26.5 34,810,797 11.8
Dicyclomine 1,317,179 22.2 20,669,937 7.0
Glycopyrrolate 222,748 3.8 19,877,577 6.7
Clidinium/Chlordiazepoxide 731,965 12.3 11,525,984 3.9
Diphenoxylate 372,133 6.3 7,711,178 2.6
Pantoprazole 45,496 0.8 7,384,419 2.5
Omeprazole 76,680 1.3 5,384,300 1.8
Esomeprazole 38,526 0.6 4,546,806 1.5
Methscopolamine 70,911 1.2 4,393,505 1.5
Other 383,137 6.3 7,201,054 2.4
TOTAL 5,935,584 100.0% $294,660,695 100.0%

Table 7. All Functional Intestinal Disorders: Number and Age-Adjusted Rates of Ambulatory Care Visits and Hospital Discharges With First-Listed and All-Listed Diagnoses by Age, Race, and Sex in the United States, 2004

Source: National Ambulatory Medical Care Survey (NAMCS) and National Hospital Ambulatory Medical Care Survey (NHAMCS) (3-year average, 2003–2005), and Healthcare Cost and Utilization Project Nationwide Inpatient Sample (HCUP NIS)

Demographic Characteristics Ambulatory Care Visits First-Listed Diagnosis Number in Thousands Ambulatory Care Visits First-Listed Diagnosis Rate per 100,000 Ambulatory Care Visits All-Listed Diagnosis Number in Thousands Ambulatory Care Visits All-Listed Diagnosis Rate per 100,000 Hospital Discharges First-Listed Diagnosis Number in Thousands Hospital Discharges First-Listed Diagnosis Rate per 100,000 Hospital Discharges All-Listed Diagnosis Number in Thousands Hospital Discharges All-Listed Diagnosis Rate per 100,000
AGE (Years)
Under 15
1,347 2,215 2,384 3,921 10 17 48 79
AGE (Years)
15–44
1,710 1,359 3,256 2,588 29 23 248 197
AGE (Years)
45–64
1,127 1,594 2,700 3,820 30 42 341 483
AGE (Years)
65+
1,762 4,851 3,308 9,104 45 124 603 1,660
Race
White
5,039 2,057 9,690 3,980 86 35 944 373
Race
Black
633 1,513 1,391 3,702 16 54 169 546
Sex
Female
3,886 2,518 7,778 5,074 76 47 808 496
Sex
Male
2,059 1,484 3,871 2,815 39 29 432 328
Total 5,945 2,025 11,648 3,967 115 39 1,241 423

Figure 5. All Functional Intestinal Disorders: Age-Adjusted Rates of Ambulatory Care Visits and Hospital Discharges With All–Listed Diagnoses in the United States, 1979–2004

The rate of ambulatory care visits over time (age-adjusted to the 2000 U.S. population) is shown by 3-year periods (except for the first period which is 2 years), between 1992 and 2005 (beginning with 1992–1993 and ending with 2003–2005). Rates of both ambulatory care visits and hospitalizations have increased in recent years. Ambulatory care visits per 100,000 rose from 2,732 in 1992-1993 to 3,955 in 2003-2005. Hospitalizations per 100,000 decreased from 195 in 1979 to 131 in 1990 and then rose to 299 in 2004.
Source: National Ambulatory Medical Care Survey (NAMCS) and National Hospital Ambulatory Medical Care Survey (NHAMCS) (averages 1992–1993, 1994–1996, 1997–1999, 2000–2002, 2003–2005), and National Hospital Discharge Survey (NHDS)

Table 8. All Functional Intestinal Disorders: Number and Age-Adjusted Rates of Deaths and Years of Potential Life Lost (to Age 75) by Age, Race, and Sex in the United States, 2004

Source: Vital Statistics of the United States

Demographic Characteristics Underlying Cause Number of Deaths Underlying Cause Rate per 100,000 Underlying Cause Years of Potential Life Lost in Thousands Underlying or Other Cause Number of Deaths Underlying or Other Cause Rate per 100,000
AGE (Years)
Under 15
6 0.0 0.4 27 0.0
AGE (Years)
15–44
21 0.0 0.9 106 0.1
AGE (Years)
45–64
49 0.1 0.9 335 0.5
AGE (Years)
65+
347 1.0 0.2 1,721 4.7
Race
White
381 0.1 1.9 1,941 0.7
Race
Black
36 0.1 0.5 214 0.8
Sex
Female
266 0.1 0.9 1,297 0.7
Sex
Male
157 0.1 1.6 892 0.7
Total 423 0.1 2.5 2,189 0.7

Figure 6. All Functional Intestinal Disorders: Age-Adjusted Rates of Death in the United States, 1979–2004

The death rate was stable from 1979 to 1999, when the change to ICD-10 coding resulted in an increase. Underlying-cause mortality per 100,000 was 0.12 in 1979 and 0.14 in 2004. All-cause mortality per 100,000 was 0.53 in 1979 and 0.72 in 2004.
Source: Vital Statistics of the United States

Table 9. All Functional Intestinal Disorders: Costliest Prescriptions

Source: Verispan

DRUG Prescription (#) Prescription Retail Cost Cost
Tegaserod 1,618,699 11.6% $238,030,688 32.0%
Lansoprazole 695,616 5.0 85,935,464 11.6
Polyethylene glycol 3350 2,647,099 19.0 84,291,600 11.3
Esomeprazole 395,269 2.8 64,101,386 8.6
Pantoprazole 592,957 4.3 60,350,131 8.1
Hyoscyamine 1,787,325 12.8 40,443,459 5.4
Lactulose 1,278,184 9.2 30,168,691 4.1
Rabeprazole 303,450 2.2 29,843,464 4.0
Omeprazole 303,450 1.7 23,755,697 3.2
Glycopyrrolate 242,494 1.7 20,706,229 2.8
Other 4,114,833 29.6 65,854,357 8.9
Total 13,914,807 100.0% $743,481,166 100.0%
Last Reviewed January 2008