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Supplements Economic Impact of Irritable Bowel Syndrome: What Does the Future Hold?
Economic Impact of Irritable Bowel Syndrome: What Does the Future Hold?
Brooks Cash, MD, FACP
Tegaserod Treatment for IBS: A Model of Indirect Costs
Dean G. Smith, PhD; Victoria Barghout, MSPH; and Kristijan H. Kahler, SM
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Effectiveness of Tegaserod Therapy on GI-related Resource Utilization in a Managed Care Population
Judith J. Stephenson, SM; Victoria Barghout, MSPH; Kristijan H. Kahler, SM; Joaquim Fernandes, BA; Jane F. Beaulieu, MSN; Samuel Joo, MS; and Stephen J. Boccuzzi, PhD
Budget Impact of Tegaserod on a Managed Care Organization Formulary
Michael A. Bloom, BA; Victoria Barghout, MSPH; Kristijan H. Kahler, SM; Judith Bentkover, PhD; Hannah Kurth, BA; Ian M. Gralnek, MD, MSHS; and Brennan M. R. Spiegel, MD, MSHS
Impairment in Work Productivity and Health-related Quality of Life in Patients With IBS
Bonnie B. Dean, PhD; Daniel Aguilar, MPH; Victoria Barghout, MSPH; Kristijan H. Kahler, SM; Feride Frech, MPH; David Groves, PhD; and Joshua J. Ofman, MD
Participating Faculty

Effectiveness of Tegaserod Therapy on GI-related Resource Utilization in a Managed Care Population

Judith J. Stephenson, SM; Victoria Barghout, MSPH; Kristijan H. Kahler, SM; Joaquim Fernandes, BA; Jane F. Beaulieu, MSN; Samuel Joo, MS; and Stephen J. Boccuzzi, PhD

This study sought to determine the real-world effectiveness of tegaserod therapy on gastrointestinal (GI)-related resource utilization in a managed care population with a retrospective, longitudinal pre-/post-parallel cohort study of tegaserod users and a matched reference cohort of tegaserod nonusers through medical and pharmacy claims data from a large, geographically diverse, managed care organization. Continuously enrolled benefit-eligible patients newly initiated on tegaserod therapy (index prescription) were identified between August 1, 2002, and June 30, 2003, and were categorized (using International Statistical Classification of Diseases, 9th Revision, Clinical Modification codes) as having irritable bowel syndrome (IBS) or another GI-related disorder (eg, gastroesophageal reflux disease). GI-related resource utilization (office visits, hospitalizations, emergency department visits, endoscopic and nonendoscopic procedures, and GI drug prescriptions) was determined for the 6-month period before and after the index prescription date for tegaserod users and nonusers. The study population consisted of 3365 tegaserod users and 3364 matched nonusers. Within-cohort differences before and after therapy were tested using the Wilcoxon signed rank test. The mean age of 3365 tegaserod users and 3364 matched nonusers was 47 years (+15 years); 92% were women, 47% had an index diagnosis of IBS, and 53% had an index diagnosis of another GI-related disorder. Within-cohort GI resource utilization comparisons before and after therapy initiation showed significant decreases (P < .01) in all utilization categories, except GI drug prescriptions, for tegaserod users; these decreases were not consistently observed for matched nonusers. Tegaserod use appeared to be associated with consistent decreases in GI-related resource utilization after 6 months of therapy; similarly consistent reductions were not observed in tegaserod nonusers. These early findings suggest that tegaserod may provide important clinical and economic benefits.

(Am J Manag Care. 2005;11:S35-S42)

Although the cause of irritable bowel syndrome (IBS) has eluded researchers for many years, recent advances in clinical research have implicated the role of serotonin (5-hydroxytryptamine [5-HT]) in gastrointestinal (GI) motility disorders. Three main physiologic manifestations of IBS lead to varied GI symptoms, including impaired GI motility, altered intestinal secretion, and increased visceral sensitivity.1 More than one of these mechanisms may account for a patient's symptoms, but no single factor has been shown to fully explain the pathophysiology of IBS.

Although there is no cure for IBS, treatments typically aimed at the relief of individual symptoms include diet modification, changes in lifestyle, pharmacotherapeutic agents, and psychotherapy alone and in combination.2,3 In addition, none of the currently available pharmacologic agents used to treat the individual symptoms of IBS, including antispasmodics, antidepressants, and laxatives, have been successful in managing IBS long term.4,5

One recently approved drug that targets multiple IBS symptoms is tegaserod maleate, a highly selective serotonin type 4 (5-HT4) receptor agonist that has been approved in the United States for short-term use (≤12 weeks) for women with IBS with constipation (IBS-C) and, more recently, for men and women younger than 65 years old with chronic idiopathic constipation.6

Interestingly, the treatment gap related to IBS remains a significant issue. A survey of the American Gastroenterology Association membership indicated that IBS accounts for 12% of diagnoses made by primary care physicians and 28% of diagnoses made by gastroenterologists.7 In addition, among gastroenterologists, IBS was found to be the most common diagnosis.8 According to another study, in 1998 IBS was responsible for approximately 3.65 million office visits, 500 000 hospital inpatient stays, 150 000 hospital outpatient visits, and 87 000 emergency department visits.9

This increased utilization of healthcare resources is also associated with a significant economic burden. At a national level, the estimated annual direct medical costs associated with IBS in the United States have been estimated to be as high as $10 billion.10-12 Included in these costs are primary care and specialist physician visits, outpatient and inpatient care, and diagnostic testing, but not prescription or nonprescription medication costs.9,12,13 A study of Medicaid recipients found that expenditures were approximately 48% to 58% higher in patients with IBS than in matched controls.11 A similar pattern of increased healthcare utilization was also observed in a study of all adult members who had undergone flexible sigmoidoscopy and who were surveyed regarding IBS symptoms in a managed care setting. This study found that IBS patients had more outpatient visits, were admitted to the hospital more often, and filled more total outpatient prescriptions than non-IBS patients and that their total costs were 51% higher.12

IBS has also been found to have a considerable impact on indirect costs, including decreased work and academic productivity and reduced quality of life (QOL).2 Leong and colleagues10 found that the costs of medically related work absenteeism were significantly higher for employees with IBS than for employees without IBS. Absenteeism (days missed from work) and presenteeism (decreased productivity at work) rates were reduced 20% among bank employees with IBS and 6% among those without IBS.14,15 Furthermore, other studies have shown that the decrease in work productivity associated with IBS was greater than that associated with many other long-term episodic diseases, including asthma16 and migraine,17 and was comparable with that associated with the long-term persistent conditions of hypertension18 and congestive heart failure.19 Patients with IBS have been shown to experience significant impairment in QOL, including the performance of daily activities, 20,21 and have reported that IBS symptoms negatively affect their social lives, sexual and physical relationships,22 and school attendance.23

Although it has been shown that tegaserod is efficacious in providing global relief of the multiple symptoms of IBS and that it significantly improves patient QOL compared with placebo,20,24 no effectiveness studies have been conducted regarding the benefits of tegaserod from a managed care perspective. In this study, we investigated whether tegaserod therapy was associated with a decrease in GI-related healthcare resource utilization for a cohort of tegaserod users and a matched cohort of tegaserod nonusers. We compared GI-related healthcare utilization rates for the 6-month periods before and after the actual tegaserod index date or an assigned index date based on user status and cohort matching criteria.

Subjects and Methods

This study was a retrospective, longitudinal, pre-/post-parallel cohort study of tegaserod users and a matched reference cohort of tegaserod nonusers. The study included medical and pharmacy claims data from the data warehouse of a large, geographically diverse, managed care organization (MCO). The data warehouse contains administrative claims for more than 14 million members. Four years of current and historical longitudinal member-level administrative claims data are maintained in the warehouse. In addition to medical and pharmacy claims data, the data warehouse includes such information as member demographic data, provider data, product information, and laboratory test results. The prestudy and poststudy design was chosen to minimize confounding and selection bias. A similar analysis in a matched cohort of nonusers was conducted to investigate possible regression to the mean.

Cohort Identification. Adults 18 years and older were identified as tegaserod users if they had at least 1 pharmacy claim for tegaserod between August 1, 2002, and June 30, 2003. The date of the first tegaserod prescription became the index prescription date. Benefit eligibility and continuous enrollment criteria of 6 months before and after the index prescription date were applied. Tegaserod users were assigned an index diagnostic category of IBS or GI-related based on International Statistical Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) codes on the medical claim for an office, outpatient, or emergency department visit or an inpatient hospitalization closest (+15 days) to the index prescription date. The patient was assigned the index diagnostic category of IBS if the medical claim had an ICD-9-CM code of IBS. If there was no IBS code but there was at least 1 ICD-9-CM code for another GI-related disorder (eg, esophageal disorders, gastritis/dyspepsia, gastroenteritis, gastroesophageal reflux disease, abdominal pain), the patient was assigned the diagnostic category of GI-related. The date of the medical claim was defined as the index diagnostic date.

Tegaserod nonusers were adults 18 years of age and older with 1 or more medical claims for office visits, outpatient visits, emergency department visits, and inpatient hospitalizations between July 15, 2002, and July 15, 2003. Benefit eligibility and continuous enrollment criteria during the study period were applied. Medical claims were classified as IBS or as GI-related using the methodology that was developed for the tegaserod cohort. If there was an ICD-9-CM code for IBS on the medical claim, it became classified as IBS; if there was no IBS code but there was at least 1 code for a GI-related disorder, the medical claim was classified as GI-related. Dates of IBS/GI-related medical claims were identified as index diagnostic dates. Nonusers without at least 1 IBS or GI-related medical claim were deleted from the analysis.

Tegaserod users were matched with nonusers 1:1 for sex, age, index diagnostic category, and index diagnostic date. The matching procedure identified exact matches on sex and index diagnostic category and then selected the nearest possible nonuser match based on age and index diagnostic date. After matching, tegaserod nonusers were assigned the index prescription date of their user match. The baseline evaluation period was defined as the 6-month period before the actual index prescription date for the tegaserod user cohort and the "assigned" index prescription date for the nonuser cohort, and the follow-up evaluation period was defined as the 6 months including and after the actual or assigned index prescription date.

Outcome Measures and Statistical Analysis. The primary outcome measure was GI-related resource utilization by category of service (ie, office visits, hospital stays, emergency department visits, endoscopic and nonendoscopic procedures, and GI medications), as determined by the number of claims during the 6-month period before and after the index date. Each person served as his or her own control in assessing change before and after the actual or assigned index prescription date.

The significance of before and after differences for tegaserod users and nonusers was determined by means of the Wilcoxon signed rank test. SAS version 8.2 (SAS Institute, Cary, NC) was used to extract and prepare the data files, and SPSS version 11.0 (SPSS, Chicago, Ill) was used to generate descriptive analytic tables and to perform statistical calculations.

Results

Demographic and Clinical Characteristics. The study initiation period was tied to the US Food and Drug Administration (FDA) approval of tegaserod in July 2002. We identified 5023 tegaserod users with at least 1 prescription for tegaserod between August 1, 2002, and June 30, 2003. After applying benefit eligibility and continuous enrollment criteria, 3365 (67%) tegaserod users remained. Matching resulted in 3364 matched pairs of tegaserod users and nonusers; 1 tegaserod user had no reference group match. Thus, the study population consisted of 3365 tegaserod users and 3364 matched tegaserod nonusers.

Demographic characteristics of the 2 cohorts are summarized in Table 1. The mean age of participants in each cohort was 47 years + 15 years. Most (54%) patients were between 41 and 64 years of age, and 11% were 65 years or older. Ninety-two percent of participants in each cohort were women. In terms of the index diagnostic category, 47.3% of participants in each cohort were categorized as having a documented IBS claim, and 52.7% were categorized as having a GI-related diagnostic claim. However, within the GI-related diagnostic category, tegaserod users had more medical claims with ICD-9-CM codes for intestinal disorders than nonusers (40.8% vs 21.5%), whereas nonusers had more claims for GI and digestive disorders (39.3% vs 28.6%).

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