Chapter 17: Appendicitis

The Burden of Digestive Diseases in the United States

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

Being an acute surgical condition, appendicitis was not especially common at ambulatory care visits, but did account for an estimated 600,000 first-listed ambulatory care visits (Table 1), which was as frequent as those for ulcerative colitis or pancreatitis. Visit rates were nearly equal across age groups up to age 65. Rates were higher among blacks and males. Hospital discharges more accurately reflected disease occurrence. In 2004, there were an estimated 325,000 hospitalizations with a diagnosis of appendicitis, of which 91.7 percent were first-listed diagnosis. This proportion of first-listed diagnoses was higher than that of any other digestive disease and changed little over 20 years.¹² Discharge rates did not differ markedly by age. The rate among whites was twice that of blacks, while the rate for males was 20 percent greater than that for females.

Rates of ambulatory care visits increased from 1992–1993 to 2003–2005, but the more significant trends were for hospital discharges (Figure 1). Hospitalizations with a diagnosis of appendicitis declined from 1979 through 1995, continuing a decline that began at least in 1965, if not earlier.¹³ Between 1995 and 2004, the trend reversed, such that there was a 34 percent increase in the rate of hospital discharges with a diagnosis of appendicitis.

Deaths from appendicitis were uncommon in 2004, with the large majority occurring at age 65 years and older, indicating a high case-fatality rate among older persons (Table 2). Mortality rates from appendicitis continued a many-year decline until 1991 (Figure 2). From 1991 onward, rates remained stable.

Because appendicitis is a surgical condition requiring hospitalization, prescriptions filled at retail pharmacies captured through the Verispan database (Appendix 2) were not frequent nor necessarily representative of the medications used in this condition. In 2004, there were an estimated 315,000 such medications prescribed, at a retail cost of $5.6 million. More than 98 percent of these medications were for pain relievers, with the rest for antimicrobial agents.

References

Table 1. Appendicitis: 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	106	174	163	267	61	101	63	103
AGE (Years) 15–44	358	284	458	364	156	124	169	134
AGE (Years) 45–64	133	188	150	212	58	83	65	93
AGE (Years) 65+	—	—	—	—	21	59	26	72
Race White	469	200	607	260	232	99	253	107
Race Black	—	—	139	355	18	45	21	53
Sex Female	260	179	372	258	126	86	144	98
Sex Male	341	232	410	279	164	112	172	118
Total	601	205	782	266	298	101	325	111

Figure 1. Appendicitis: 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 increased from 189 in 1992–1993 to 269 in 2003–2005. Hospitalizations per 100,000 declined from 129 in 1979 to 87.5 in 1995. Between 1995 and 2004, the trend reversed such that the rate increased to 117 in 2004.

Table 2. Appendicitis: 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	21	0.0	1.4	33	0.1
AGE (Years) 15–44	31	0.0	1.4	45	0.0
AGE (Years) 45–64	97	0.1	1.9	168	0.2
AGE (Years) 65+	304	0.8	0.3	516	1.4
Race White	378	0.1	3.7	646	0.2
Race Black	59	0.2	1.0	90	0.3
Sex Female	200	0.1	1.4	341	0.2
Sex Male	253	0.2	3.6	421	0.3
Total	453	0.2	5.0	762	0.3

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

Mortality rates declined until 1991, after which they remained stable. Underlying-cause mortality per 100,000 decreased from 0.35 in 1979 to 0.16 in 1991 and was 0.15 in 2004. All-cause mortality per 100,000 decreased from 0.63 in 1979 to 0.32 in 1991, and was 0.25 in 2004.

Last Reviewed January 2008

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