Irritable bowel syndrome (IBS) is one of the most common

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Costs of Care for Irritable Bowel Syndrome

in Managed Care

Jean-François Ricci, PharmD, MBA, Priti Jhingran, PhD, Trent McLaughlin, PhD, and Eric G. Carter, MD, PhD

• Objective: To measure the charges associated with the diagnosis and treatment of irritable bowel syndrome (IBS) and to compare them with charges associated with asthma care.

• Design: Retrospective cohort analysis.

• Patients: The study population was selected using the PharMetrics Integrated Outcomes medical and phar-macy claims database. Patients were required to have an index visit between 1 July 1996 and 30 September 1997, with a primary diagnosis of IBS as defined by ICD-9-CM code 564.1. Patients had to be eligible for a minimum of 6 months before and after the index visit. • Outcome measures: Demographic information, treat-ment patterns, overall charge data, and the most com-mon diagnostic and/or surgical procedures were col-lected for IBS patients.

• Results: A total of 2770 IBS patients and 2770 age- and gender-matched asthma patients were included in the study. Total charges for the 12-month study period were comparable between the IBS ($7547 per patient per year) and asthma ($7170 per patient per year) cohorts. However, trends observed in the 2 groups differed. Charges for asthma patients reflected the impact of an exacerbation of their asthma, whereas charges for IBS patients remained elevated throughout the 12-month period, peaking only slightly at the time of the diagno-sis. Among IBS patients, 20% of patients accounted for 66% of all charges. The most common gastrointestinal procedures were colonoscopy (15% of patients), endo-scopy (10%), and cholecystectomy (1.5%). The 20% of patients who accounted for the majority of charges were more likely to undergo a colonoscopy (P < 0.001), upper endoscopy (P < 0.001), or gallbladder removal (P < 0.001) than the remaining 80% of patients. • Conclusion: IBS represents a substantial cost burden

to managed care. Even after diagnosis is documented, patients continue to undergo a lengthy and costly diagnostic process. There is a need for more effective IBS diagnostic and pharmacologic management to decrease the cost burden of IBS, particularly in man-aged care settings.

I

rritable bowel syndrome (IBS) is one of the most com-mon gastrointestinal disorders encountered in primary care and gastroenterology practices [1,2]. The primary symptoms are chronic, recurrent abdominal pain and dis-comfort and alterations in bowel function, including diar-rhea and/or constipation [3]. Symptoms may increase or decrease over time [4]. Epidemiologic data indicate that prevalence of the disorder in the United States may be as high as 10% in men and 20% in women [5–7].

Although the pathophysiology of IBS is unknown, a hypothesis for the etiology of the syndrome includes dys-regulation of local and central neural control of gut function [8,9]. Diagnosis is made on the basis of positive clinical fea-tures and the exclusion of disorders that have similar mani-festations, such as food allergies, malabsorption, intestinal infections, inflammatory bowel disease, diverticulitis, and colon cancer [10]. It may take some time before the diagno-sis becomes apparent [11]. Treatment for IBS may include dietary modification, exercise, patient education, and phar-macotherapy directed at individual symptoms. A new drug shown to be clinically effective in managing the multiple symptoms of IBS, alosetron, was recently approved for the treatment of female IBS patients whose predominant bowel symptom is diarrhea [12–14].

Although IBS is not a life-threatening condition, the diffi-culty in diagnosis and lack of good treatment options pro-duce high social and medical costs [15,16]. The total annual direct costs of IBS in the United States have been estimated at $8 billion [17]. The actual health care costs associated with IBS are difficult to determine because there is no ICD-9-CM [18] code that is specific to IBS.

In this study, we use a medical and pharmacy claims database to assess the total health care utilization charges of

Jean-François Ricci, PharmD, MBA, Health Outcomes Scientist, Health Outcomes Department, U.S. Medical Affairs, Glaxo Wellcome Inc., Research Triangle Park, NC; Priti Jhingran, PhD, Principal Health Outcomes Scientist, Health Outcomes Department, U.S. Medical Affairs, Glaxo Wellcome Inc.; Trent McLaughlin, PhD, NDC Health Information Services, Phoenix, AZ; and Eric G. Carter, MD, PhD, International Therapeutics Director, U.S. Medical Affairs, Glaxo Wellcome Inc.

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IBS patients in a managed care environment. To put these findings into context, we compare charges associated with IBS with those associated with asthma. Asthma is a chronic, prevalent, and well-studied condition associated with a sig-nificant burden of illness in managed care [19,20].

Methods Data Source

Patient-level clinical and charge data were abstracted from the PharMetrics Integrated Outcomes medical and pharma-cy claims database [21]. The database contains claims for 1.6 million covered lives from over 20 managed care health plans across the United States, allowing for the longitudinal retrospective examination of resources consumed by contin-uously enrolled member populations. Data accuracy is checked at the source by the individual health plans and at PharMetrics before integration into a single database. PharMetrics uses Symmetry Health Data Systems’ Episode Treatment Groups illness classification software [22] to create its episode-based database. The software captures clinically relevant services provided during a patient’s treatment and organizes the data into “episodes of care.”

Patients

Patients presenting with a primary diagnosis of irritable colon (ICD-9-CM code 564.1) between 1 July 1996 and 30 September 1997 were identified in the database. Although no ICD-9-CM code is specific to IBS, IBS is a main identifier of code 564.1. The date of first claim with a primary diagno-sis code of 564.1 was termed the index date. Patients needed to have at least 6 months of continuous enrollment preceding and following the index date and had to be free of any claim with a 564.1 diagnosis code during the 6 months preceding the index date to be eligible for the study. To better under-stand the relative impact of IBS on total cost of care, an age-and gender-matched comparison cohort of asthma patients was identified in the database using the primary diagnosis ICD-9-CM code 493.XX. Patients presenting with a diagnosis of chronic obstructive pulmonary disease (491.XX and 493.2) or cystic fibrosis (277.XX) or with 2 or more prescriptions for ipratropium bromide within the 12-month period were excluded.

Data Analysis

Integrated claims data were analyzed by NDC Health Information Services (Phoenix, AZ) to assess patient demo-graphics and medical and pharmaceutical utilization. Total monthly medical and pharmaceutical charges were assessed for the 12-month study period. Charges and utilization incurred at the index date were included in the post-index period. Diagnostic, evaluative, and surgical procedures were identified using Current Procedural Terminology (CPT)

codes [23]. Facility charges, as identified by Symmetry’s Grouper as associated with a length of stay equal to or greater than 1 day were considered indicators of hospitalizations (inpatient charges). The Uniform System of Classification (USC) was used to determine the presence of specific pre-scription medications [24]. All analyses were performed using SAS software, version 7.0 [25]. Student t tests adjusted for multiple comparisons were used to investigate differences in charges between the 2 groups; alpha level was set at 0.05. Time-series analyses with corrections for first-order autore-gressive errors were conducted to assess the temporal impact of the diagnosis on total charges.

Results

A total of 17,366 patients presented with a primary diagno-sis classified as 564.1 between 1 July 1996 and 30 September 1997; 2770 met the inclusion criteria. Demographic charac-teristics of the IBS and asthma cohorts are presented in

Table 1. The mean age of IBS patients was 51.9 years, and 77% were female.

Among IBS patients, anti-infectives were the most commonly prescribed medication class, with 47% of patients receiving at least 1 prescription (Table 2). The majority of these patients (965/1294, 75%) initiated anti-infective thera-py prior to their index date. Anxiolytics were also widely prescribed; 29% of all IBS subjects received at least 1 anxi-olytic prescription. In general, IBS patients were more likely to start therapy with IBS-related medications before receiv-ing an IBS diagnosis rather than after diagnosis. For exam-ple, 309 (70%) of the 443 subjects receiving a prescription for dicyclomine began therapy prior to diagnosis. Younger patients were more likely to receive an IBS medication than were older patients. Approximately 39% of patients under 55 years of age received an IBS medication, compared with 27% of patients over 55 years.

The most common gastrointestinal (GI) procedures in IBS patients were colonoscopy (15% of patients), endoscopy (10%), and cholecystectomy (1.5%). Endoscopy was more likely to be performed prior to the index date, whereas colonoscopy and cholecystectomy were more likely to be performed following diagnosis. Genitourinary (GU) proce-dures (eg, hysterectomy, tubal ligation) were performed on approximately 2% of all female IBS patients.

Table 3presents total medical charges for IBS and asthma subjects during the study period. The 1-year mean total charge for IBS patients was $7547, or $629 per IBS patient per month; the mean total charge for asthma patients was $7170, or $598 per asthma patient per month. Inpatient charges were comparable in the asthma and IBS cohorts and were the largest contributor to total charges. However, outpatient and ancillary charges were higher in the IBS cohort, whereas drug charges were higher in the asthma cohort. These differences

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were statistically significant, even after controlling for test multiplicity with a Bonferroni correction.

Twenty percent of the patients in the IBS cohort account-ed for 66% of all expenditures and 53% of all GI and GU pro-cedures. These patients were older (P < 0.001), presented with more comorbidities (P < 0.001), and were more likely to undergo a colonoscopy (P < 0.001), endoscopy (P < 0.001), or gallbladder removal (P < 0.001) than the remaining 80%.

The mean total charges per month for IBS and asthma patients over the 12-month study period are presented in the

Figure. For asthma patients, the month of the diagnosis (exac-erbation) of asthma is associated with a large increase in total charges. A temporary but smaller increase around the index date is observed in the IBS cohort, but this increase is observed as early as the month prior to the index date. IBS patients also exhibit higher baseline charges than asthma patients. Time-series analyses with corrections for first-order autoregressive errors were conducted to better reflect the temporal impact of a diagnosis of IBS or asthma on total health care charges. Analyses showed that the IBS cohort experienced a significant increase in run-in charges the month before the index date (+$287; P = 0.0026) and a significant shift in baseline charges post–index date (+$131; P = 0.0456). In the asthma cohort, there was a major increase in charges in the month of the index date (+$1014; P = 0.001) preceded by a smaller increase in run-in charges in the month prior to the index date (+$247;

P = 0.0161) and a significant shift in baseline charges post–

index date (+$271; P = 0.0119).

Discussion

IBS patients are high health care utilizers. IBS patients average 3.6 physician visits per year for GI and/or non-GI symptoms, translating to up to 3.5 million physician visits annually [26]. The economic impact of IBS is not limited to direct costs: it extends to lost productivity and other indirect costs [27].

Total health care charges over the 12-month study period for IBS patients were not different from those of the asthma cohort. Like asthma patients, IBS patients incur a large major-ity of health care utilization in hospital use (41% of all charges), which is reflected in IBS patients by high rates of GU and GI procedures (eg, colonoscopy, endoscopy, cholecystectomy). As is frequently observed, a small portion of patients (20%) was responsible for the majority of charges (66%).

IBS is known to be a chronic condition associated with periodic exacerbations of symptoms [4]. The trends observed in monthly expenditures (Figure) around the time of diagno-sis support the periodic nature of IBS. Total charges for IBS subjects increased around the time of the diagnosis but with a lesser amplitude (4 times less) than for asthma patients. The temporary increase observed around the time of diagnosis reflects the direct impact of an acute episode on health care resource utilization, a phenomenon observed in other dis-ease states with acute events, such as ischemic stroke [28]. Asthma patients experience a larger increase in charges around the time of diagnosis, whereas IBS patients are char-acterized by higher baseline charges. This sharp contrast in utilization patterns between the 2 cohorts may indicate that in IBS there exists a continued uncertainty surrounding the

Table 1.Characteristics of IBS and Age- and Gender-Matched Asthma Patients

IBS Cohort Asthma Cohort (n= 2770) (n= 2770) Female, n (%) 2131 (77%) 2131 (77%) Mean age (SD) 51.9 (19.6) 52.6 (18.0) Age, n (%) ≤35 yr 544 (20%) 544 (20%) 36–55 yr 1043 (38%) 1043 (38%) 56–64 yr 371 (13%) 371 (13%) ≥65 yr 812 (29%) 812 (29%)

IBS = irritable bowel syndrome; SD = standard deviation.

Table 2. Commonly Prescribed Medications in IBS Patients (n = 2770)

Prescription Prescription Subjects Before On or After Receiving Index Date Index Date Medication

Medication No. of Patients (%)

All medications Anti-infectives 965 (35) 329 (12) 1294 (47) Antispasmodics 929 (34) 232 (8) 1161 (42) Laxatives 89 (3) 60 (2) 149 (5) Antidiarrheals 76 (3) 36 (1) 112 (4) Benzodiazepines 348 (13) 456 (16) 804 (29) Tricyclic antidepres- 238 (9) 104 (4) 342 (12) sants Other antidepressants 264 (10) 96 (3) 360 (13) IBS-related medications Dicyclomine 309 (11) 134 (5) 443 (16) Hyoscyamine 196 (7) 146 (5) 342 (12) Belladonna 39 (1) 32 (1) 71 (3) Chlordiazepoxide/ 11 (< 1) 6 (< 1) 17 (< 1) clidinium Alprazolam 154 (6) 66 (2) 220 (8) Lorazepam 137 (5) 77 (3) 214 (8)

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accuracy of a lengthy diagnosis process (leading to further testing). Also, the multiple symptoms that are characteristic of IBS have proven to be a hurdle in the management of the condition, and until recently, traditional pharmacologic treat-ment options have shown limited efficacy in addressing the multiple symptoms of IBS [6,29,30].

Approximately 75% of the IBS study cohort were female, reflecting current epidemiologic data on the distribution of IBS by gender [26]. Although the reasons for the gender dif-ferences are not known, women may have lower visceral pain thresholds than men and an increased tendency for dysregulation of the central and local neural pathways reg-ulating visceral pain perception and gut function [31–33]. The mean age in the IBS cohort was 52 years, which is some-what higher than previous estimates, although ranges are similar [6].

Several limitations of this study must be acknowledged. Identification of subjects in the IBS cohort was based on the presence of ICD-9-CM code 564.1. Although IBS is the major subcategory of this code, it is possible that some patients without IBS may have inadvertently been included in the study. Conversely, patients receiving a diagnosis code other than 564.1 were omitted from study whether or not they actually had IBS. This limitation is inherent to all database studies and will be difficult to correct until a universal code for IBS is defined. Also, expenditure (charge) data are based on the amount charged by a health professional for services rendered and may overestimate the true cost to the provider. This study contributes to our understanding of the cur-rent treatment and cost burden of IBS in managed care. Future research should focus on the refinement of algo-rithms to allow for better identification of IBS patients from secondary claims databases. This will help health service researchers better quantify health care utilization costs directly derived from IBS. In addition, as new therapeutic options for IBS become available, their impact on resource utilization will need to be evaluated.

The authors thank Patrice C. Ferriola, Glaxo Wellcome Inc., for writing and editing assistance.

Author addresses: Dr. Ricci: jfr56309@glaxowellcome.com. Dr. Jhingran: pj24628@glaxowellcome.com. Dr. Carter: 5 Moore Drive, PO Box 13398, Research Triangle Park, NC 27709. References

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Table 3. Total Charges for IBS and Age- and Gender-Matched Asthma Patients over 12 Months

IBS Cohort Asthma Cohort

(n= 2770) (n= 2770)

Type of Charges Mean (SD) % Total Mean (SD) % Total

Outpatient charges $2058* (3565) 27.3 $1760* (3602) 24.5

Pharmacy charges $607* (969) 8.0 $745* (1029) 10.4

Inpatient charges $3074*(10,521) 40.8 $3196*(10,004) 44.6

Ancillary charges $1808* (3584) 23.9 $1467* (13,802) 20.5

TOTAL CHARGES $7547*(14,255) 100.0 $7170*(13,802) 100.0

IBS = irritable bowel syndrome; SD = standard deviation. *P < 0.05 using Bonferroni correction.

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–6 –5 –4 –3 –2 –1 +1 +2 +3 +4 +5 +6

IBS charges Asthma charges

Mean monthly charges, $

1800 1500 1200 900 600 300 0

Months before and after index date

Figure.Mean total monthly charges for irritable bowel syndrome (IBS) and age- and gender-matched asthma patients before and after index date.

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This study was funded by Glaxo Wellcome Inc.

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