BOSTON (FRONTLINE MEDICAL NEWS) – Hospital-acquired respiratory viral infections may be a significant and underappreciated cause of morbidity and mortality among hospitalized patients.

According to a multisite, retrospective chart review of 44 patients with hospital-acquired respiratory viral illnesses (HA-RVIs), 17 patients (39%) died in-hospital. Further, of the 27 who survived, 18 (66.6%) were discharged to an advanced care setting rather than to home, though just 11/44 (25%) had been living in an advanced care setting before admission.

For the hospitalizations complicated by HA-RVI, the average length of stay was 30.4 days, with a positive respiratory virus panel (RVP) result occurring at a mean 18 days after admission.

“HA-RVIs are an underappreciated event and appear to target the sickest patients in the hospital,” said coauthor Dr. Matthew Sims , director of infectious diseases research at Beaumont Hospital, Rochester, Mich., at a poster session of the annual meeting of the American Society of Microbiology.

First author Dr. Adam K. Skrzynski , also of Beaumont Health, and his coauthors performed the analysis of 4,065 patients with a positive RVP result during hospitalization at a regional hospital system in the September 2011-May 2015 study period; the 1.1% of patients with positive results who formed the study cohort had to have symptoms of a respiratory infection occurring after more than 5 days of hospitalization. Mortality data were collected for the first 33 days of hospitalization.

Positive RVP results for those included in the study came primarily from nasopharyngeal swab (n = 32), with the remainder from bronchoalveolar lavage (n = 11) and sputum (n = 1). Most patients were female (29/44, 66%), and elderly, with an average age of 73.8 years. In an interview, Dr. Sims said that many patients were smokers, and that chronic obstructive pulmonary disease and obesity were common comorbidities.

The prognosis was particularly grim for the 12 patients (27.3%) who were admitted to the ICU: 10 (83.3%) died after an average 9.6 days in the ICU. Advanced interventions did not seem to make a difference, either. “Intubation didn’t help these patients,” said Dr. Sims. Nine patients (20.5%) were intubated within 7 days of their positive RVP results. Intubation lasted an average 7.6 days, and all nine of these patients died.

The RVP came into use in 2011 and made it possible to identify whether a respiratory virus was causing symptoms – and which virus was the culprit – said Dr. Sims. For the studied population, 13 of 44 patients had influenza; 11 of those had influenza A and 2 had influenza B. The next most common pathogen was parainfluenza, with 10 positive RVP results.

Dr. Sims said he and his coinvestigators were surprised to find that, although influenza A was the most common pathogen, only 18.8% of the patients with influenza A died during the study period. “While it is possible that the high frequency of influenza infection in our study may be due to poor vaccine-strain matching for the years in question, the lower mortality rate seen in influenza A infection may be due to our hospital’s mandatory influenza vaccination policy and subsequent protection against mortality,” Dr. Skrzynski and his coauthors wrote.

There were seasonal trends in mortality, with 70.6% of mortality occurring in the spring (April-June) and an additional 23.3% happening in the winter (January-March). Parainfluenza infection peaked in the spring, and influenza peaked in the winter months.

Dr. Sims said the study underlines the importance of encouraging ill hospital staff members to stay home, and family members with respiratory symptoms should not be visiting fragile patients. Dr. Skrzynski and his coauthors also wrote that “immunization of healthcare personnel against influenza should be mandatory.”

Still to be answered, said Dr. Sims, is the association between comorbidities and the potentially lethal effects of HA-RVIs. They are currently performing a matched case-control study to tease out these relationships.

Dr. Skrzynski reported no outside funding source, and the study authors had no financial disclosures.

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