Critically Appraised Topic:

Does the use of the pneumococcal vaccine prevent pneumonia

in middle aged and elderly people?

Date: March 2, 1998

Appraised by: Deb Bynum, MD

Clinical Bottom Lines:

1) Among middle aged and elderly patients (50-85 years of age) hospitalized for community aquired pneumonia (CAP), the pneumococcal vaccine given after discharge did not decrease the incidence of recurrent pneumonias (19% of the patients in the vaccine group and 16 % of the patients in the placebo group had developed a new pneumonia during follow-up).

2) Pneumococcal pneumonia was diagnosed (blood, sputum, pleural cultures or serology) in 16 (4.5%) patients in the placebo group and 19 (5.6%) of patients in the vaccine group -- again, no difference.

3)There was no difference in mortality in patients vaccinated compared to those who received placebo.

4) Only one patient in the vaccine group acquired a bacteremic pneumococcal pneumonia compared to five in the placebo group (however, this was not statistically significant). Of interest, all six bacteremic strains belonged to serotypes included the vaccine.

5) S. pneumoniae was the cause of pneumonia in over 60% of patients with an established etiological diagnosis.

6) The incidence of pneumonia increased significantly with age, but there was no difference within each age group between patients vaccinated or not (incidence per 100 person-years of 4.0 in the 50-65 age group, 5.4 in the 66-75 year group, and 11.6% in the 76-85 year group for patients in the placebo group compared to 5.0, 8.6, and 10.7 respectively for those in the vaccine group.

The Evidence:

Prospective, multicenter, double-blind, randomised, placebo-controlled trial: 691 non-immunocompromised patients aged 50-85 years treated for CAP were randomly assigned to receive either 23-valent pneumococcal vaccine or placebo. Primary endpoints were pneumonia and pneumococcal pneumonia and secondary endpoints included bacteremic pneumococcal pneumonia and overall mortality.

Comments:

1) Overall, 58% (894 patients) were excluded for multiple reasons including presumed "poor compliance" including mental impairment or severe alcoholism and immunocompromised states including malignancy, multiple myeloma, HIV, dialysis, or asplenia. These exclusions include the patients that are currently included in the list of those that we aim to vaccinate-- whether or not adding these patients to the study would actually strengthen the conclusions drawn in the paper is not clear.

2) Although the specific diagnosis of "pneumococcal pneumonia" was not often made, the clinical endpoints of recurrent pneumonia of any cause and mortality are more relevant for practice.

3) The observation that patients in older age groups are both more likely to develop CAP and less likely to respond to vaccination in a clinically significant way raises into serious question our current strategy with the recommendations to vaccinate only those who are older or chronically ill.

Reference: Ortqvist et al. Randomised trial of 23 valent pneumococcal capsular polysaccharide vaccine in prevention of pneumonia in middle-aged and elderly people. Lancet 1998; 351: 399-403