Vaccination Cuts Risk of Severe Flu in Hospitalized Patients With COPD

A large national study from Canada showed influenza vaccination is effective in reducing flu-related hospitalizations among patients with chronic obstructive pulmonary disease (COPD). Hospitalized patients who tested positive for the flu and had COPD and were unvaccinated had worse death rates and more severe illness than those who were vaccinated.

Despite recommendations to get flu shots, patients with COPD have a low uptake of the vaccination—about 50% to 60%. The researchers said initiatives to increase vaccination rates as well as early antiviral use among patients with COPD could reduce flu-related hospitalization, severe illness, and lower healthcare costs.

Previous research inferring poor outcomes in this population of patients with COPD comes from studies of elderly patients with a mix of chronic lung diseases, according to the study, which was published in the journal CHEST.

Forty-six hospitals across 5 Canadian provinces participated in this study. Patients with COPD, hospitalized with any acute respiratory illness or exacerbation, were studied between 2011 to 2015 and were included if their flu vaccination status was known. All patients received nasopharyngeal swabs with polymerase chain reaction (PCR) testing for influenza. The primary outcome was an influenza-related hospitalization.

Among 4755 hospitalized COPD patients, 4198 (88.3%) patients with known vaccination status were analyzed. The adjusted analysis demonstrated a 38% reduction in influenza-related hospitalizations in vaccinated versus unvaccinated individuals.

Compared with hospitalized patients without the flu, patients with influenza (1490/4198, 35.5%) were older (age >75 years; 50.8% vs 47.6%), more likely to be smoking (34.2% vs 26.9%), more likely to reside in long-term care (9.2% vs 7%), and less likely to be vaccinated during the season of hospitalization (58.9% vs 70.6%).

Influenza positive patients (n = 1833, 38.5%) experienced higher crude mortality (9.7% vs 7.9%, P = .047), and critical illness (17.2% vs 12.1%, P <.001) compared with influenza-negative patients. However, in the adjusted analysis, vaccination wasn’t associated with significant mortality reduction (odds ratio [OR], 0.9; 95% CI 0.6-1.4).

Patients with the flu also needed mechanical ventilation more than patients without the flu. Risk factors for mechanical ventilation included diabetes (OR, 1.7; 95% CI, 1.1-2.6) and current smoking (OR, 3.2; 95% CI, 1.5-7.2).

Risk factors for mortality in flu-positive patients included aged >75 years (OR 3.7; 95% CI, 0.4-30.3), cardiac comorbidity (OR, 2; 95% CI, 1.3-3.2), residence in long-term care (OR, 2.6; 95% CI, 1.5-4.5), and home oxygen use (OR, 2.9; 95% CI, 1.6-5.1).

Care gaps were identified, including low influenza vaccination rates and delayed start of antiviral therapy in this study of patients with COPD, where 34% of hospitalized patients were not vaccinated at the time of hospitalization. The vaccination rate was not statistically different between oxygen-dependent and non-dependent patients (50.8% vs 47.6%).

Reference

Mulpuru S, Ye L, Hatchette T, et al. Effectiveness of influenza vaccination on hospitalizations and risk factors for severe outcomes in hospitalized patients with chronic obstructive pulmonary disease (COPD). CHEST. 2019;155(1):69-78. doi: 10.1016/j.chest.2018.10.044.