| Abstract: | Patients with diabetes have an increased risk of gastric cancer (1,2), and metformin may protect against gastric cancer (3). This study investigated whether metformin might protect against Helicobacter pylori infection, an important risk factor of gastric cancer.The reimbursement database of Taiwan ’ s National Health Insurance was used. Disease diagnoses were based on the ICD-9-CM. Diabetes was coded 250. XX, and H. pylori infection was de fi ned by a diagnostic code of 041.86 plus receiving H. pylori eradication therapy (4). A propensity score (PS)-matched cohort (based on the Greedy 8 → 1 digit match algorithm) (3) comprised 16,060 metformin ever users and 16,060 metformin never users with new-onset diabetes, who were enrolled during 1999 – 2005 and followed up until the end of 2011. Patients with type 1 diabetes, cancer diagnoses, or H. pylori infections at entry or within 6 months of diabetes diagnosis, aged , 25 or . 75 years at entry, or with a follow-up duration , 6 months were not included. PS was derived from covariates including age, sex, occupation, living region, hypertension, dyslipidemia, obesity, nephropathy, eye disease, stroke, ischemic heart disease, peripheral arterial disease, chronic obstructive pulmonary disease, tobacco abuse, alcohol-related diagnoses, heart failure, gingival and periodontal diseases, pneumonia, osteoporosis, tuberculosis infection, disease of pancreas, diseases of esophagus, stomach, and duodenum, Epstein Barr virus infection, hepatitis B virus infection, hepatitis C virus infection, and use of insulin, sulfonylureas, meglitinides, acarbose, rosiglitazone, pioglitazone, ACE inhibitors/ angiotensin receptor blockers, calcium channel blockers, statins, fi brates, and aspirin. Hazard ratios (HRs) were estimated by Cox regression incorporated with the inverse probability of treatment weighting using PS (3). Standardized difference was calculated for each covariate, and a cutoff . 10% may indicate potential confounding (5). |
