MIAMI BEACH — Acid-suppressive medication is associated with a 30% increased risk of hospital-acquired pneumonia compared with nonexposure, according to a recent report.
“These medications are potentially responsible for 180,000 excess cases of hospital-acquired pneumonia annually,” lead investigator Dr. Shoshana J. Herzig commented at the annual meeting of the Society of General Internal Medicine. “We believe these should be used more judiciously” than they are currently used in the non-ICU population.
Proton pump inhibitors were significantly associated with an increased risk of pneumonia, but histamine2 receptor blockers were not.
In U.S. hospitals, an estimated 40%-70% of inpatients receive acid-suppressive medication (ASM). In about half the cases, ASM therapy is prescribed for the first time while the patient is in the hospital (Ann. Pharmacother. 2006;40:1261-6; Am. J. Gastroenterol. 2000;95:3118–22). Prophylaxis of stress ulcers in low-risk patients is a common reason these agents are ordered (Am. J. Gastroenterol. 2006;101:2200–5).
In the current study, up to 70% of the indications for ASMs were not well investigated or supported by the literature, Dr. Herzig and her associates reported (JAMA 2009;301:2120–8).
Other studies have suggested that the risk of community-acquired pneumonia is increased among people taking ASMs in an outpatient setting (Ann. Intern. Med. 2008;149:391–8; Arch. Intern. Med. 2007;167:950–5).
Dr. Herzig and her associates found that more than half of 63,787 non-ICU admissions to Beth Israel Deaconess Medical Center in Boston from January 2004 to December 2007 had an order for a proton-pump inhibitor (PPI) and/or a histamine2 receptor blocker. Of these admissions, 2,219 (3.5%) later had an ICD-9 code for bacterial pneumonia as a secondary discharge diagnosis, said Dr. Herzig, chief medical resident and general medicine fellow at the hospital.
Inpatients who received an ASM had a higher rate of hospital-acquired pneumonia, 4.9%, compared with 2.0% of unexposed patients (unadjusted odds ratio, 2.6). The adjusted odds ratio was 1.3, indicating a 30% higher risk associated with this practice, based on a multivariable analysis that controlled for 50 possible confounders and comorbidities.
“We found PPIs, in particular, were associated with increased risk,” Dr. Herzig said. This association was significant (OR, 1.3), but an order for a histamine2 receptor blocker was not (OR, 1.1).
Why ASM agents, and especially PPIs, are associated with a higher risk of pneumonia is unknown. Dr. Herzig and her coworkers hypothesized that impairment of white blood cell function might play a role.
The mean age of the study population was 54 years; men comprised 37% of the cohort. Inpatients prescribed an ASM were more likely to be male, to be older, and to have heart disease or diabetes. Taking these factors into account, Dr. Herzig and her associates did a validation study and found the same higher risk of hospital-acquired pneumonia (adjusted OR, 1.3) in 16,396 patients with an ASM order, compared with 16,396 demographically similar unexposed patients.
The generalizability of the findings may be limited by the fact that the study was conducted at a single large urban medical center. Results should be validated at other institutions, she said.
Dr. Herzig and her associates did not disclose any conflicts of interest. The study was funded through a grant from the Department of Health and Human Services that supports the Fellowship in General Medicine and Primary Care at Harvard Medical School.