Risk for Death From Pneumonia Rises Without Flu Vaccine

Ingrid Hein

October 21, 2019

When a patient with pneumonia is admitted to the hospital, a flu shot can reduce the risk for readmission and death, report investigators.

Pneumonia accounts for 50% of deaths during the flu season, but the influenza vaccine is underused, said Kam Sing Ho, MD, from Mount Sinai St. Luke's and Mount Sinai West in New York City.

"We already know the benefit of vaccination. It doesn't require weight loss, exercise, or medication, just a discussion," he told Medscape Medical News.

"We are missing out on a good opportunity to offer the flu vaccine," he explained at CHEST 2019 in New Orleans. "If someone is in the hospital for 5 or 6 days, we should be having the vaccine discussion at least once."

A national discussion about the role of the flu vaccine in the prevention of influenza and resulting complications, such as pneumonia, is ongoing.

Just last month, William Schaffner, MD, medical director of the National Foundation for Infectious Diseases, explained the preventative effects to the public in his promotion of the annual flu vaccine. "Vaccine is clearly the best way to protect yourself and your loved ones," he said during a news conference.

"We need to remember that even if you get influenza after having received the vaccine, you are likely to benefit by having a less severe and shorter illness. And more important, you're less likely to suffer the complications, including pneumonia, hospitalization, and dying," he continued.

If someone is in the hospital for 5 or 6 days, we should be having the vaccine discussion at least once.

In their retrospective study, Ho and his colleagues looked at 735,120 hospitalizations for community-acquired pneumonia in the Agency for Healthcare Research and Quality 2014 HCUP Nationwide Readmission Database.

Only 13,983 (1.9%) of these patients received a flu shot during admission. "That's not a lot," Ho pointed out. All-cause readmission within 30 days was 11.9%, but pneumonia was the reason for readmission in 81.0% of those cases.

To assess how effective that in-hospital flu shot was for reducing all-cause readmission and secondary outcomes, such as reason for readmission and readmission mortality and morbidity, and to identify independent risk factors for readmission, the researchers used the Cox proportional hazards model.

Patients were matched for hospital setting (urban or rural), hospital bed size, insurance, age, sex, and household income. "We really wanted to make sure we compared apples to apples," Ho told Medscape Medical News.

The researchers compared 9777 patients with community-acquired pneumonia who received the influenza vaccination with 9777 who did not.

Readmission rates were lower in patients who were vaccinated during their initial hospitalization than in those who were not (8.6% vs 11.0%). Death rates during readmission were significantly lower for vaccinated than unvaccinated patients (1.11% vs 2.96%; P < .001).

And mortality rates during a second hospital readmission were significantly lower in vaccinated than in unvaccinated patients (1.3% vs 5.5%; P < .001).

In-hospital vaccination reduced readmission by 6.5% (hazard ratio, 0.82; 95% confidence interval, 0.69 - 0.98; P < .028), and it is an independent predictor of readmission. Advanced age, Medicare insurance, comorbidities, atrial fibrillation, and acute respiratory failure are also independent predictors, the researchers note.

Influenza Vaccine Saves Lives and Money

In addition to health issues, there is a hefty financial burden related to not using measures to prevent hospital readmission. The cost of the 489,247 inpatient hospital days incurred by the readmission of unvaccinated patients amounts to $1 billion borne by the hospital and $3.67 billion borne by insurers, Ho said.

Since the introduction of the Medicare value-based purchasing program in 2012, which lowers payments to Inpatient Prospective Payment System (IPPS) hospitals with excess readmissions, it has become even more important to evaluate what causes readmission. "The American College of Physicians emphasizes prevention," he said. "And a flu vaccine is simple prevention."

The routine vaccination of patients hospitalized with pneumonia could have positive effects on readmissions rates and hospital funding. "All it would take to decrease rates of readmission is to take a moment before discharge," Ho said. "Ask yourself, can I do anything to prevent a readmission here? Let's talk about offering a vaccine."

CHEST 2019: American College of Chest Physicians Annual Meeting. Presented October 21, 2019.

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