Utilization Patterns and Net Direct Medical Cost to Medicaid of Irritable Bowel Syndrome

Bradley C. Martin; Rahul Ganguly; Sandhya Pannicker; Feride Frech; Victoria Barghout


Curr Med Res Opin. 2003;19(8) 

In This Article


This is the first study to assess the impact of IBS on Medicaid expenditures. Our results indicate that IBS imposes a significant economic burden on the Medicaid programs of California and North Carolina. In both states, IBS-related health care utilization rates and expenditures were significantly higher for patients than for matched controls for nearly all service categories, especially ambulatory care. Mean Medicaid expenditure PMPY for IBS cases were 48% and 59% higher than those for matched controls from California and North Carolina, respectively. These results are similar to those from a study by Levy et al.,[18] in which total direct costs for patients with IBS in a health maintenance organization were 49% higher than costs for population controls. As in the Levy[18] study, the greatest increases observed in the current study occurred for ambulatory care, with 70% or more of unadjusted net incremental expenditures attributable to spending on prescription drugs, physician visits, and outpatient visits.

Adjusted net incremental expenditure per IBS case in North Carolina ($1630) is greater than that for asthma, another chronic episodic condition, for which net expenditures were estimated at approximately $1300 per year in North Carolina Medicaid during a similar time frame.[23] Although the prevalence of treated IBS is lower than that of asthma in North Carolina Medicaid, the results of the current study demonstrate the significant economic burden that IBS poses on the health care system.

Patients among the IBS Medicaid cohorts received approximately three prescriptions per month (for IBS or comorbid conditions), representing a 50% increase over the rates observed for matched controls. A recent retrospective analysis of prescribing patterns for GI drugs used in IBS demonstrated that patients with IBS rely on polytherapy more often than continuous monotherapy for managing symptoms, thus driving up costs. Median outpatient and prescription costs for GI-related drugs were 49% and 113% higher among patients taking multiple medications (either switching between medications frequently or augmenting current therapy) than among patients taking continuous monotherapy.[24] Previous studies have shown that medications commonly prescribed for patients with IBS for the treatment of IBS symptoms include anxiolytics, antispasmodics, laxatives, and antidiarrheals.[2,10] The wide range of medications used by patients with IBS shows that traditional treatment options target individual symptoms but do not address the multiple symptoms of IBS.

On average, patients with IBS saw a physician more often than once a month in California, in addition to the 0.3 outpatient visits per month. Patients with IBS in North Carolina saw a physician nearly twice a month in addition to the 0.7 outpatient visit per month. These physician and outpatient utilization rates are approximately 100% higher than rates in matched controls. As has been reported for patients in a health maintenance organization,[17] inpatient utilization rates among IBS cases and controls were similar, suggesting that IBS is managed on an outpatient basis and has little impact on hospitalization rates. The frequency of physician and outpatient visits observed among IBS cases underscores that IBS is a chronic condition associated with periodic symptom exacerbations that may cause patients to seek medical care repeatedly.[25]

Despite differences between the Medicaid programs in California and North Carolina that likely influenced patient selection and fostered between-state differences (e.g. plan features in terms of prescription coverage), prescription expenditures and utilization rates for IBS observed within each state were approximately 1.5 times those of controls, suggesting that these results might be generalized to other Medicaid programs.

The utilization and expenditure findings observed in the original cohort also were seen among the probable IBS cases employed in the sensitivity analysis. In North Carolina, similar net unadjusted and adjusted expenditures were observed among definite and probable IBS cases. However, in California, net adjusted expenditures for probable IBS cases ($2025) were considerably higher than for definitive IBS cases in the final cohort ($838). This difference might have arisen from the inclusion criteria used to create this cohort, which might have selected a sicker population of patients with subsequently higher utilization rates. In comparison with California, baseline expenditures in North Carolina were relatively high, which may explain why large increases in health care utilization and expenditures were not observed in this state among probable IBS cases.

The rate of comorbidity was high for definitive IBS cases in California and North Carolina, especially those relating to mental health (depression and psychoses). Prevalence rates for depression were approximately 300% higher in IBS cases than in matched controls. These findings are consistent with previous observations that patients with IBS are approximately twice as likely as those without IBS (1) to be diagnosed with non-GI disorders (e.g. mental disorders, chronic fatigue syndrome, fibromyalgia, chronic pelvic pain) and (2) to visit physicians for non-GI-related complaints (three times as often).[26,27]

Many patients with IBS (42-94%), particularly those presenting to tertiary care centers, have psychological disturbances such as depression and generalized anxiety disorder.[26,28] However, a study evaluating psychosocial function among IBS consulters, presented as an abstract at the American College of Gastroenterology meeting in 2002, found that most IBS consulters have low levels of psychosocial distress.[29] Further, a definitive link between psychological conditions and specific IBS symptoms has not been established.[26]

The IBS cohort in the current study comprised patients who were predominantly middle-aged and female, characteristics that are similar to those previously described for patients with IBS.[26,27] Consistent with the predominance of IBS in the middle-aged population, the costs of care were greater for patients with IBS aged 41 to 65 than for younger or older patients.

Although our prevalence estimates of 1-2% are comparable with the treated prevalence rates, they are lower than those from population-based surveys, which report an IBS prevalence of 10-20% in the general population.[2,3,30,31] Several methodologic factors may account for this. First and foremost is the inability of a claims-based analysis to detect IBS cases that are not diagnosed or are misdiagnosed or miscoded. In addition, middle-aged persons (aged 41 to 65), who in this study had a greater prevalence of IBS compared with older and younger subjects, are under-represented in Medicaid programs.

The disparity between the treated prevalence rates and those in population-based surveys also highlights the lack of implementation or the inconsistent use in clinical practice of IBS diagnostic criteria (e.g. Rome), treatment guidelines,[32,23] or evidence- and consensus-based treatment algorithms.[34] This can lead to unnecessary resource utilization (e.g. excessive testing to rule out organic disease, visits to multiple health care providers) and, subsequently, increased expenditures. New diagnostic guidelines and treatment recommendations recently released by the American College of Gastroenterology present a practical, stepwise diagnostic approach and an evidence-based review of treatment options, including serotonin modulators (e.g. a 5-HT3 antagonist and a 5-HT4 agonist) that target the multiple symptoms of IBS.[35] Future research should be directed at assessing the impact these treatment guidelines have on the care of IBS patients in various systems of care. Also, health system managers would be interested in learning the impact of the newest IBS therapies on the cost of caring for IBS patients.


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