Chronic obstructive pulmonary disease (COPD) is a common condition that has a significant negative impact on morbidity and mortality rates and health care costs. Approximately one third of acute exacerbations of COPD may be caused by viral infections. These infections can lead to increased rates of bacterial infections. To combat viral infections, current recommendations for management of COPD include annual influenza immunization. These recommendations are based on observational studies that have shown that influenza immunizations reduce the number of hospitalizations, decrease risk of pneumonia, and reduce mortality rates. Few data are available from randomized trials that evaluate influenza immunization in patients with COPD. Wongsurakiat and colleagues studied the effectiveness of influenza vaccination on influenza-related acute respiratory illness in patients with COPD.
The trial was a stratified, randomized, double-blind, placebo-controlled study of patients with COPD who regularly attended a university hospital’s COPD clinic. Patients were included if they met spirometry criteria for COPD. Participants were divided into mild, moderate, and severe categories based on the severity of their disease, and then randomly assigned to receive active influenza vaccination or placebo. The outcome measurements were the number and severity of total acute respiratory illnesses, based on outpatient treatment, hospitalization, and mechanical ventilation requirement; and the number of episodes and severity of influenza-related acute respiratory illnesses.
A total of 125 patients participated in the study. The incidence of influenza-related acute respiratory illness was 28.1 per 100 person-years in the placebo group and 6.8 per 100 person-years in the vaccination group. This difference was statistically significant and was found in all three severity groups. The vaccine effectiveness was 84 percent in patients with mild COPD, 45 percent in the moderate group, and 85 percent in the severe group. Bivariate analysis revealed that the effectiveness of the vaccine was no different based on severity of COPD, comorbid diseases, age, sex, or smoking status. Patients who received the vaccine were less likely to be hospitalized or placed on a ventilator secondary to influenza-related acute respiratory illness. When evaluating the total acute respiratory illness incidence and severity, no difference was noted between participants who received the vaccine and those who received placebo. The probability of acquiring an influenza-related respiratory illness was significantly less in the vaccine group compared with the placebo group.
The authors conclude that influenza vaccination is highly effective in preventing influenza-related acute respiratory illness in patients with COPD, regardless of the severity of their disease. They add that influenza vaccination should be recommended to all patients who have COPD.
editor’s note: Despite the recommendations for routine influenza immunization in various populations, a significant number of people fail to receive this vaccine. In a recent report1 from the Centers for Disease Control and Prevention (CDC), 66 percent of adults 65 years or older had received an influenza vaccination in the previous year. This is substantially below the 90 percent goal for 2010.1 The CDC recommends system-based approaches (e.g., standing orders) to improve the percentage of patients receiving the influenza immunization.—k.e.m.