Study Title:

Antacids Increase Pneumonia Risk by 30%

Study Abstract

Context The use of acid-suppressive medication has been steadily increasing, particularly in the inpatient setting, despite lack of an accepted indication in the majority of these patients.

Objective To examine the association between acid-suppressive medication and hospital-acquired pneumonia.

Design, Setting, and Patients Prospective pharmacoepidemiologic cohort study. All patients who were admitted to a large, urban, academic medical center in Boston, Massachusetts, from January 2004 through December 2007; at least 18 years of age; and hospitalized for 3 or more days were eligible for inclusion. Admissions with time spent in the intensive care unit were excluded. Acid-suppressive medication use was defined as any order for a proton-pump inhibitor or histamine2 receptor antagonist. Traditional and propensity-matched multivariable logistic regression were used to control for confounders.

Main Outcome Measure Incidence of hospital-acquired pneumonia, defined via codes from the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM), in patients exposed and unexposed to acid-suppressive medication.

Results The final cohort comprised 63 878 admissions. Acid-suppressive medication was ordered in 52% of admissions and hospital-acquired pneumonia occurred in 2219 admissions (3.5%). The unadjusted incidence of hospital-acquired pneumonia was higher in the group exposed to acid-suppressive medication than in the unexposed group (4.9% vs 2.0%; odds ratio [OR], 2.6; 95% confidence interval [CI], 2.3-2.8). Using multivariable logistic regression, the adjusted OR of hospital-acquired pneumonia in the group exposed to acid-suppressive medication was 1.3 (95% CI, 1.1-1.4). The matched propensity-score analyses yielded identical results. The association was significant for proton-pump inhibitors (OR, 1.3; 95% CI, 1.1-1.4) but not for histamine2 receptor antagonists (OR, 1.2; 95% CI, 0.98-1.4).

Conclusions In this large, hospital-based pharmacoepidemiologic cohort, acid-suppressive medication use was associated with 30% increased odds of hospital-acquired pneumonia. In subset analyses, statistically significant risk was demonstrated only for proton-pump inhibitor use.

From press release:

Hospitalized patients who receive acid-suppressive medications such as a proton-pump inhibitor have a 30 percent increased odds of developing pneumonia while in the hospital, according to a new study.

With the introduction of proton-pump inhibitors, used primarily in the treatment of ulcers and gastroesophageal reflux disease, the use of acid-suppressive medications has increased significantly over the last several years, with estimates that between 40 percent and 70 percent of hospitalized patients receive some form of them. But this high use in the inpatient setting has been of concern for several reasons, including use for indications that are not supported by research and data suggesting an increased risk for community-acquired pneumonia with use in outpatient settings, according to background information in the article.

Shoshana J. Herzig, M.D., of Beth Israel Deaconess Medical Center, Boston, and colleagues examined the association between acid-suppressive medication use and hospital-acquired pneumonia. The study included data on patients who were admitted to a large, urban, academic medical center from January 2004 through December 2007, including patients who were at least 18 years of age, hospitalized for 3 or more days, and not admitted to the intensive care unit. Acid-suppressive medication use was defined as any order for a proton-pump inhibitor or histamine2 receptor antagonist. The study included data on 63,878 hospital admissions.

Overall, acid-suppressive medication was ordered in 32,922 admissions (52 percent). Of the group who received these medications, 27,236 (83 percent) received proton-pump inhibitors and 7,548 (23 percent) received histamine2 receptor antagonists, with some exposed to both. The majority of these medications were ordered within 48 hours of admission (89 percent).

Hospital-acquired pneumonia occurred in 2,219 admissions (3.5 percent). The unadjusted incidence of hospital-acquired pneumonia was higher in the group exposed to acid-suppressive medication relative to the unexposed group (4.9 percent vs. 2.0 percent). After further analysis and adjusting for potential factors that could influence the outcomes, receiving acid-suppressive medications was associated with a 30 percent increased odds of hospital-acquired pneumonia. The association was significant for proton-pump inhibitors but not for histamine2 receptor antagonists.

The researchers write that acid-suppressive medications have been thought to increase the risk of pneumonia via modification of upper gastrointestinal bacteria, and, as a result, respiratory bacteria.

"These results occur in the context of an increasing body of literature suggesting an association between acid-suppressive medication and pneumonia. Further scrutiny is warranted regarding inpatient prescribing practices of these medications," the authors conclude.



Study Information

Shoshana J. Herzig, Michael D. Howell, Long H. Ngo, Edward R. Marcantonio.
Acid-Suppressive Medication Use and the Risk for Hospital-Acquired Pneumonia.
JAMA.
2009 May
Beth Israel Deaconess Medical Center, Boston.

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