TABLE I.

MODEL VARIABLES: BASELINE VALUES AND RANGES USED IN SENSITIVITY ANALYSIS

Variable	Base case	Range	Reference
H. pylori and precancerous lesions prevalence
H. pylori seroprevalence (%)	70	30–80	26, 27
Baseline prevalence at age 20 (%)
Gastritis	65	–	28
Atrophy	18	–	28
Intestinal metaplasia	12	–	28
Dysplasia	5	–	28
Clinical
Invasive cancer to symptomatic cancer1	0.25	0.2–0.3	2
Five-year gastric cancer survival rate (%)	20	18–23	29–31
Monthly all-cause mortality rate	0.0001–0.04693	–	32
Screening and treatment
H. pylori diagnostic test characteristics (%)
Serology test
Sensitivity	90	85–95	33–35
Specificity	90	79–98	33–35
C13 urea breath test
Sensitivity	95	92–98	35
Specificity	95	94–99	35
Treatment effectiveness4
Relative risk of progression to atrophy	0.1–0.7	5	8, 18, 36
Relative risk of regression to gastritis	2.0–2.4	5	8, 18, 36
Direct medical costs, US $ (2005)6
Outpatient visit	1.8	0.9–3.5	37
H. pylori serology test	1.6	0.7–3.8	33, 37–40
H. pylori C13 urea breath test	8.0	3.2–14.5	37, 39
Antibiotic treatment for H. pylori	4.3	2.0–12.0	8, 36, 41, 42
Gastric cancer treatment	2615	250–5230	33, 37, 43, 44
Program costs (%)7	25.0	12.5–50.0	2
Quality of life, weights
Normal gastric mucosa	0.566–0.945	3	45
Gastritis	0.566–0.945	3	45
Atrophy	0.566–0.945	3	45
Intestinal metaplasia	0.566–0.945	3	45
Dysplasia	0.566–0.945	3	45
Symptomatic gastric cancer	0.49	0.17–0.79	46

¹Monthly probability.

²Based on expert opinion.

³Values are age- and sex-specific.

⁴Values are sex-specific and vary by natural history parameter set.

⁵For sensitivity analysis, base case estimate was varied ±25%.

⁶Unit costs, except where noted. See Supplementary Appendix for details on upper and lower bound estimations.

⁷Percent of initial outpatient visit and serology test costs.