[aladoc99]

Looking at the article in BMJ Open, I don't see that they controlled for obesity, either by BMI or any other measure. This is a huge confounder, making reflux symptoms worse and being an independent predictor of mortality. If I'm right, this is a huge oversight on their part.

[jawilson2]

"External adjustment to estimate the impact of three unmeasured confounders, including obesity, smoking and use of therapeutics including anticoagulants, antiplatelet agents and non-steroidal anti-inflammatory drugs, shows a net confounding bias of 9.66% (see online supplementary figure 5). The total bias could move a null association between PPI and death from HR 1.00 to HR 1.10 (reflecting the net positive bias of 9.66% rounded up to 10.0%). The association we observed between PPI and death was 1.25>1.10, which cannot be fully due to bias of unmeasured confounding."

"Covariates included age, race, gender, eGFR, number of outpatient serum creatinine measurements, number of hospitalisations, diabetes mellitus, hypertension, cardiovascular disease, peripheral artery disease, cerebrovascular disease, chronic lung disease, cancer, hepatitis C, HIV, dementia and diseases associated with acid suppression therapy use such as gastro-oesophageal reflux disease (GERD), upper gastrointestinal (GI) tract bleeding, ulcer disease, Helicobacter pylori infection, Barrett’s oesophagus, achalasia, stricture and oesophageal adenocarcinoma.25–28 eGFR was calculated using the abbreviated four-variable CKD epidemiology collaboration equation based on age, sex, race and outpatient serum creatinine.29 Race/ethnicity was categorised as white, black or other (Latino, Asian, Native American or other racial/ethnic minority groups). Comorbidities except for hepatitis C and HIV were assigned on the basis of relevant ICD-9-CM (the International Classification of Diseases, Ninth Revision, Clinical Modification) diagnostic and procedure codes and Current Procedural Terminology (CPT) codes in the VA Medical SAS data sets.2 30–33 Hepatitis C and HIV were assigned based on laboratory results."

http://bmjopen.bmj.com/content/7/6/e015735

That all said, this journal doesn't have a great impact factor (2.37), so this definitely falls under "huh, this warrants further study."