18 Jan

Test and treat strategies for Helicobacter: PATIENTS AND METHODS

Decision tree: The decision-analytic model was constructed using DATA software (TreeAge Software Inc, Williams- town, Massachusetts). A hypothetical cohort of 1000 pa­tients under the age of 50 years who had presented to their primary care practitioner with a new complaint of dyspepsia and did not use nonsteroidal anti-inflammatory drugs was used. Three initial management strategies were compared – empirical treatment with a four-week course of oral raniti- dine, H pylori testing using serology and H pylori testing using the 13C-UBT. Each strategy was evaluated with respect to costs and outcomes over a one-year period and from the viewpoint of a third-party payer for health care, considering only direct health care costs to the Ontario Ministry of Health. Health outcomes were quantified as the number of patients in whom H pylori-associated PUD was cured, in the sense that the ulcer was healed and the organism was eradi­cated.

In developing the path probabilities and management ap­proaches applied to the model, three simplifying assump­tions were made. First, it was assumed that gastric carcinoma would not develop in the hypothetical ‘low risk’ cohort. Sec­ond, it was assumed that endoscopy with antral biopsies for histology (including special stains for H pylori) and rapid urease testing was 100% accurate for the diagnosis of H pylori infection. Third, costs and outcomes up to and including only the first recurrence of symptoms were modelled, and the costs and consequences of subsequent episodes were not captured.

Within each arm, costs and consequences were modelled for six specific patient subgroups stratified by H pylori status (positive or negative) and underlying pathology (PUD, NUD or GERD). The model was designed to be entirely ‘symptom-driven’, with interventions determined by clinical response and/or recurrence rather than by endoscopic change. Thus, for example, no intervention was required for asymptomatic ulcer recurrences. Diagnoses also were not considered mutually exclusive, and patients who entered the model with PUD could develop NUD after cure of their ul­cer.

Figure 1) Schematic summary

Figure 1) Schematic summary of decision tree used for analysis. +ve Positive; -ve Negative; 13C UBT Carbon urea breath test; GERD Gastroesophageal reflux disease; HP Helicobacter pylori; NUD Nonulcer dyspepsia

The clinical management strategies followed in the model reflect recent Canadian consensus guidelines for the management of H pylori infection. Patients who ini­tially tested positive for H pylori using the C-UBT or serology were given empirically an H pylori eradication regimen (Figure 1). Patients who tested negative were prescribed a four-week course of oral ranitidine. Only if symptoms per­sisted or recurred was the patient referred to a gastroenterologist for consultation and endoscopy, which was assumed to include antral biopsies and rapid urease testing (RUT). In the ranitidine strategy, all patients whose symptoms per­sisted or recurred following the initial four-week course of ranitidine were referred for consultation and endoscopy. Medication you can afford 

In each arm of the model, endoscopically proven peptic ulcers were treated with eradication therapy if associated with H pylori infection. Peptic ulcers without evidence of H pylori infection were treated with a four-week course of oral omeprazole 20 mg bid. Patients who underwent endo- scopy and were found to have persistent H pylori infection without an ulcer were prescribed eradication therapy because it would not have been known whether they had an ulcer at entry into the model. Patients with isolated esoph- agitis at endoscopy were prescribed an eight-week course of oral omeprazole 20 mg bid, while those with normal mucosa and no H pylori received no new therapy.

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