Clinical Section

Gerontology 2003;49:246–250DOI: 10.1159/000070405

Impact of Pneumococcal Vaccinationon Morbidity and Mortality of GeriatricPatients: A Case-Controlled Study

Christian Wagnera Wolfgang Poppa Martin Poschb Clemens Vlasichc

Angelika Rosenberger-Spitzyd

a11. Medizinische Abteilung mit Lungenkrankheiten und Aufnahmestation, Geriatriezentrum am Wienerwald,bInstitute of Medical Statistics, University of Vienna, Vienna, cAventis Pasteur, Vienna, anddGeriatriezentrum am Wienerwald, Vienna, Austria

Received: December 14, 2001Accepted: September 25, 2002

Christian Wagner11. Medizinische Abteilung mit Lungenkrankheiten und AufnahmestationGeriatriezentrum am Wienerwald, Jagdschlossgasse 59A–1130 Vienna (Austria)Tel. +43 1 80110 3482, Fax +43 1 80110 3818, E-Mail wac@pul.gzw.magwien.gv.at

ABCFax + 41 61 306 12 34E-Mail karger@karger.chwww.karger.com

© 2003 S. Karger AG, Basel0304–324X/03/0494–0246$19.50/0

Accessible online at:www.karger.com/ger

Key WordsPneumococcal vaccination W Pneumonia W Elderly,vaccination

AbstractBackground: Infections due to Streptococcus pneumo-niae are the major cause of adult community-acquiredpneumonia, especially in elderly persons with chronicmedical conditions. Despite their well-documented effi-cacy against bacteraemic disease and deaths in theelderly population, pneumococcal polysaccharide vac-cines are still very much underused. Objective: A retro-spective, case-controlled study was performed to investi-gate the impact of vaccination with a polysaccharidepneumococcal vaccine, together with other risk factors,on the incidence of pneumonia and deaths in patients ina long-stay geriatric hospital. Methods: Subjects were1,077 residents in a long-stay geriatric hospital in Vienna,Austria, including 359 patients diagnosed as havingpneumonia during the period from July 1996 to October1998 and 718 control subjects. Two controls resident inthe hospital during the same time period were matchedfor each case according to demographic characteristics,chronic illness, and duration of stay in the geriatric ward.

The vaccination status was established for all subjects. Alogistic regression analysis was performed to assess theefficacy of vaccination and the impact of other cofactorson disease and death. Results: In cases and controls, 514(47.7%) had received a pneumococcal vaccine within 2years prior to the study. There were no differences indemographic characteristics, underlying medical condi-tions, or duration of stay in the hospital between vacci-nated and non-vaccinated patients. In patients diag-nosed with pneumonia, 66% were unvaccinated. Logisticregression analysis showed that vaccination significant-ly decreased the risk of pneumonia (odds ratio 0.279; p !0.0001). Of the cofactors tested, only gender (lower riskin males) and diabetes mellitus (higher risk) had anyimpact on disease risk and vaccine efficacy. There ap-peared to be a highly significant effect of vaccination,reducing the risk of all deaths (odds ratio 0.269; p !

0.0001) and deaths due to pneumonia (odds ratio 0.331;p ! 0.0001). Conclusion: This study showed that vaccina-tion with a polysaccharide pneumococcal vaccine iseffective in all groups of geriatric subjects and has a con-sequential value for health and well-being of elderlyinstitutionalized patients.

Copyright © 2003 S. Karger AG, Basel

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Pneumococcal Vaccination of the Elderly Gerontology 2003;49:246–250 247

Introduction

Pneumococcal infection is a major cause of morbidityand mortality throughout the world [1–3]. The elderly andthose with medical conditions such as chronic lung, heart,and kidney diseases, diabetes, or immunodeficiency are atincreased risk of infection and death [2]. Infections due toStreptococcus pneumoniae are the major cause of adultcommunity-acquired pneumonia requiring hospitaliza-tion; 30–50% of all pneumonia cases requiring hospital-ization being caused by S. pneumoniae [4]. This numberis very probably an underestimate due to difficulties indetermining the microbial cause of infections in patientswith pneumonia, many of whom are unable to provideadequate sputum samples. Furthermore, the routine pro-cessing of such samples for Gram staining and culture isvariable and often imprecise [5].

The efficacy of the 23-valent pneumococcal polysac-charide vaccine against bacteraemic diseases and deathsin an elderly population has been well documented [6, 7],but despite worldwide recognition of its clinical and eco-nomic value, this vaccine is still very much underused [7].While studies have demonstrated the effectiveness of vac-cination with pneumococcal vaccines in preventing inva-sive pneumococcal disease [6, 7], many results from themajor clinical trials designed to evaluate the efficacy ofthis vaccine in the elderly are inconclusive due to method-ological problems and the lack of specific and sensitivediagnostic tests for non-bacteraemic pneumococcal pneu-monia [8].

It is now widely accepted that retrospective case-con-trolled studies can be beneficial in assessing a vaccinationprogram in a ‘real-world’ situation. There, in order to pro-vide further data to support the routine use of pneumo-coccal vaccine in elderly subjects, we performed a retro-spective case-controlled study of patients with pneumoniaresiding in a large geriatric hospital in Vienna, Austria.We assessed the effect of a polysaccharide pneumococcalvaccine on the incidence of pneumonia and death andalso investigated other cofactors for morbidity and mor-tality in this group of subjects.

Subjects and Methods

Cases and controls were selected from elderly subjects residing ina long-stay geriatric hospital in Vienna (Geriatriezentrum am Wie-nerwald). Subjects were identified for whom a diagnosis of pneumo-nia (ICD 481–486) was recorded at any time form July 1996 to Octo-ber 1998. The usual methods of good clinical practice were used toarrive at a diagnosis: evaluation of symptoms, clinical examination,

laboratory analysis, and X-ray. For each case, 2 control subjects wereselected, matched for age, sex, weight, body mass index, chronic ill-nesses including cardiovascular and respiratory diseases, diabetesmellitus, tumors and malignancies, and duration of stay in the geriat-ric ward. The pneumococcal vaccination history was established forboth cases and controls. At the time of examination, the physicianshad no knowledge of whether the individual patients had receivedpneumococcal vaccinations or not.

A logistic regression analysis with backward selection of variables(vaccination, age, duration of stay in the hospital, sex, weight, bodymass index, and presence of chronic illness) and their respectiveinteractions with vaccination was performed to investigate the im-pact of the vaccine on the incidence of pneumonia, all deaths, anddeaths due to pneumonia; the effects of other cofactors on the clinicalend points and vaccine efficacy were also analyzed.

Results

Study PopulationAccording to the hospital records, a diagnosis of pneu-

monia had been recorded for 359 patients during thestudy period; 718 matched control subjects were accord-ingly selected. The mean age of the total population was82.4 B 10 years. Vaccination had been performed within2 years prior to the study period in 518 of cases and con-trols (47.7%); all had received Pneumo 23® vaccine(Aventis Pasteur MSD, France), the only pneumococcalvaccine available in Austria at the time of the study, byintramuscular injection. Over 90% of the patient popula-tion were vaccinated against influenza. There were no sig-nificant differences between vaccinated and non-vacci-nated patients with regard to demographic variables, un-derlying chronic illness, or duration of stay in the geriatricward (table 1).

Impact of Vaccination on PneumoniaThe vaccination status of the cases and controls are

summarized in figure 1. Among the 359 patents with adiagnosis of pneumonia, 237 (66%) had not been vacci-nated. Of the pneumonia cases and controls, 122 of the514 vaccinated patients (23.7%) had pneumonia com-pared with 237 of the 562 non-vaccinated patients(42.1%). Logistic regression analysis of maximum likeli-hood estimates for pneumonia diagnosis revealed thatvaccination with the polysaccharide pneumococcal vac-cine resulted in a highly significant reduction in the risk ofpneumonia in the patients studied (odds ratio 0.279; p !0.0001). There was a significant effect of gender (oddsratio 0.679 for decreased risk in males; p = 0.0453) and aninteraction between vaccination and gender (odds ratio2.111; p = 0.0172), indicating that non-vaccinated men

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248 Gerontology 2003;49:246–250 Wagner/Popp/Posch/Vlasich/Rosenberger-Spitzy

Fig. 1. Study population.

Table 1. Demographic characteristics, underlying clinical disorders,and duration of hospital stay in 1,077 geriatric patients selected in acase-control study on the efficacy of the polysaccharide pneumococ-cal vaccine (mean B SD)

Vaccinatedpatients

Non-vaccinatedpatients

CharacteristicMean age, years 82.2B10.0 82.6B10.1n 514 562

Mean weight, kg 57.1B12.7 56.3B13.3n 493 521

Mean body mass index, kg/m2 21.7B4.2 24.7B43.3n 376 238

Underlying diseases, %n 514 563Tumours/malignancies 6.7 5.1

(ICD codes 140–239.7)Cardiovascular diseases 49.2 50.3

(ICD codes 390–459.2)Respiratory diseases 4.1 2.9

(ICD codes 460–519.8)Diabetes mellitus 8.7 11.3

(ICD codes 250–250.8)

Mean duration of stayin hospital, years

4.4B5.6 3.9B4.3

n 514 562

There were no significant differences between the two groups forany parameter.

have a lower risk of pneumonia than non-vaccinatedwomen. In addition, a significant interaction betweenpresence of diabetes mellitus and vaccination (odds ratio2.373; p = 0.0042) indicated that the pneumococcal vac-cine was less effective in diabetic patients. However, bear-ing in mind that only 10% of the patients in our studypopulation had diabetes, this result must be interpretedwith caution and requires further specific investigation.No other cofactor studied had a significant influence onthe risk of pneumonia.

Impact of Vaccination on the Incidence of DeathsIn the total population of 1,077 subjects, there were

658 deaths (61.1%) from all causes recorded, 149 of whichwere specifically attributed to pneumonia. There were424 deaths in the non-vaccinated group (75.3%) versus234 in the vaccinated group (45.5%). Logistic regressionanalysis confirmed that vaccination of the elderly with thepneumococcal vaccine has a significant effect, reducingthe risk of death from any cause in institutionalized geri-atric patients (odds ratio = 0.269; p ! 0.001). There wasno other significant effect of any cofactor studied on over-all mortality. Among deaths specifically due to pneumo-nia, a significant effect of vaccination was also observed(odds ratio 0.331; p ! 0.0001). We further analyzed thedata to investigate the effect of vaccination on deaths inthe 718 control subjects only (i.e., patients without apneumonia diagnosis). In this group, vaccination with thepneumococcal vaccine was also associated with a signifi-cant reduction in the risk of death from all causes. Amongthe 355 deaths recorded in this group, 220 were in 326non-vaccinated control subjects (67%) and 135 in 392vaccinated subjects (34%). This difference in death ratesbetween vaccinated and non-vaccinated control subjectswas highly significant (chi-square test, p ! 0.001).

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Pneumococcal Vaccination of the Elderly Gerontology 2003;49:246–250 249

Discussion

The elderly are at a higher risk than the general popula-tion of developing pneumococcal infections and mortalityfrom invasive pneumococcal infections, and their infec-tions are much more severe [2]. There is a 23-valent poly-saccharide vaccine available which protects against 85–90% of the serotypes isolated in invasive pneumococcalinfections and against 90% of the antibiotic-resistantstrains. The vaccine confers substantial protection againstsystemic pneumococcal infections in the elderly and inpatients with illnesses associated with a moderately in-creased risk of pneumococcal infections [7]. Moreover,pneumococcal vaccination of elderly people is one of thefew interventions which have been found to both improvehealth and save medical costs [9]. It appears to be morecost-effective than any other medical intervention com-monly used in the care of the elderly [1, 10]. For thesereasons, pneumococcal vaccination of the elderly is rec-ommended by the World Health Organization and theAdvisory Committee on Immunization Practices for theCenters for Disease Control in the United States and byhealth authorities in at least 14 other countries worldwide[9, 11].

Nevertheless, despite these worldwide recommenda-tions reflecting the clinical and economical value of pneu-mococcal vaccination, it is still very much underused.New data are still of value to further convince healthcareproviders and patients of the necessity and benefits ofpneumococcal vaccination in an elderly population and toenhance its use. For this reason, we performed a retro-spective case-controlled study in a population of institu-tionalized geriatric patients in Austria. Consistent withthe results of retrospective case-controlled studies fromthe United States demonstrating that the vaccine prevents50–70% of invasive pneumococcal disease in elderly im-munocompetent people [1, 12], our analyses also showedthat pneumococcal vaccination significantly decreasedthe risk of pneumonia in geriatric patients. Our analysesdid not attempt to identify the aetiological cause of thepneumonia or to distinguish pneumococcal cases fromthose due to other pathogens. Nevertheless, the substan-tial impact of pneumococcal vaccination on the incidenceof pneumonia due to all causes in geriatric patients strong-ly suggests that S. pneumoniae is an important cause ofpneumonia in such subjects and emphasizes the clinicalvalue of vaccination.

According to our analysis, vaccination was associatedwith a reduced risk of deaths from all causes and of thosedue to pneumonia in the elderly populations studied.

Even considering patients without a diagnosis of pneumo-nia, the death rate was significantly lower in vaccinatedsubjects. While it is plausible that pneumococcal vaccina-tion can reduce the overall risk of death due to worseningof chronic conditions, we cannot exclude the possibilitythat, in the hospital studied, patients with a poorer prog-nosis (and thus more likely to die) were, for some reason,not vaccinated with pneumococcal vaccine (thus posi-tively biasing the absolute risk of death in the non-vacci-nated group). However, no significant differences be-tween the vaccinated and non-vaccinated groups wereobserved in terms of demographic variables and underly-ing diseases. Moreover, within deaths due to pneumonia,the significant effect of vaccination was still observed. Itshould be mentioned that this type of relationship hasbeen observed also in other studies. Nichol et al. [13]reported a reduced risk of death (risk ratio 0.71; p = 0.08)associated with pneumococcal vaccination of elderly per-sons with chronic lung diseases. These authors suggestedthat pneumococcal disease may be either directly or indi-rectly responsible for a large percentage of deaths in thisgroup of patients. Similar results have also been reportedwith influenza vaccination of the elderly.

To conclude, our retrospective analysis of hospital rec-ords shows that pneumococcal vaccination is effective insignificantly reducing the incidence of pneumonia amonginstitutionalized geriatric patients and may reduce therisk of deaths due to pneumonia and other causes. Ourresults provide further evidence of the value, and shouldbe part of clinical practice for pneumococcal vaccinationin this age group.

Acknowledgment

Aventis Pasteur carried out both the literature search and thetranslation from German into English.

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