Surya Achamma, Eapen (2009) Use of Pneumococcal Vaccine in a Tertiary Care Centre in India. Masters thesis, Christian Medical College, Vellore.
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Abstract
INTRODUCTION : Pneumonias are a major cause of morbidity and mortality among all ages of people. The leading cause for community acquired pneumonia requiring hospitalization in about 36% of the adult population is Streptococcus pneumoniae. This organism also causes other invasive and life threatening conditions such as bacterial meningitis and streptococcal bacteraemia. It is estimated that nearly 400,000 children under the age of 5 years and an equal number of adults, die of pneumonia each year in India. Although young children have the highest rates of pneumococcal disease, elderly persons and adults with certain chronic illnesses are also at high risk for invasive pneumococcal diseases. Invasive pneumococcal disease has a mean mortality of about 10% among normal individuals and this increase within the susceptible population. The increased burden of Pneumococcal disease emphasizes the need for preventive measures, namely vaccination. The efficacy of Pneumococcal vaccine in preventing invasive pneumococcal infections has been found to be about 75%. There is very little data on the use of Pneumococcal vaccine in India. Since invasive pneumococcal infections remain a major killer, it becomes necessary to study the use of Pneumococcal vaccine, including vaccination coverage and protective efficacy among the susceptible Indian population. AIMS AND OBJECTIVES : PRIMARY OBJECTIVE: 1. To determine the protective efficacy of Pneumococcal vaccine in a cohort of susceptible population in the Medical OPD followed up for a period of six months to one year. SECONDARY OBJECTIVES: 2. To determine the rate of Pneumococcal vaccination among adult subjects who visit the Medical OPD and fulfill the criteria for vaccination. 3. To describe the current prescribing practices among physicians in the Medical OPD. 4. To identify the determinants of non vaccination among patients presenting to the Medical OPD. MATERIALS AND METHODS : DESIGN: A nested case control design to determine the protective efficacy of pneumococcal vaccine among the susceptible adult population presenting to the Medical OPD. LOCATION: The study was conducted in the Out patient Clinics of the 3 Medical Units, Christian Medical College and Hospital, Vellore. DURATION: The study was conducted between a period of time from 01.07.2007 till 31.07.2008. Inclusion criteria: 1) All adults above the age of 60 years at the time of recruitment. 2) Adults between 18 and 59 years with any of the following co morbidities i. Chronic pulmonary condition like Chronic Obstructive Pulmonary Disease, Interstitial Lung Disease or Bronchiectasis. ii. Chronic cardiac condition like Coronary Artery Disease or Congestive Cardiac Failure, iii. Chronic Renal Failure, iv. Chronic Liver Disease, v. Immunocompromised conditions like Human Immuno Virus Infections or chronic steroid abuse, vi. Haematological conditions like Leukaemia, Lymphoma or Multiple Myeloma, vii. Diabetes Mellitus. LIMITATIONS : The study design was a nested case control study and not a randomized controlled trial. Subject allocation was not blinded. The subjects were recruited from OPD and later on assessed for development of outcomes by a single examiner, who was aware of the patient allocation. Therefore, the bias involved due to open assessment of outcomes cannot be excluded. An RCT gives the strongest empirical evidence of a treatment’s efficacy. Randomization of participants to the test and control arms and concealment of their allocation ensures that allocation bias and confounding of unknown variables are minimized. Nested case control studies can however provide valid and precise estimates of associations and is a cost-effective alternative for full-cohort analysis. Secondly, the rate of vaccination could have a wide error with regard to true measure of the number of subjects being vaccinated as the seasonal variation and other factors contributing to subjects’ OPD visits have not been taken into account. The number of eligible subjects presenting to Medical OPD was taken only for a particular length of time and not for the entire one year. Thirdly, there was a large number of subjects lost to follow up. About 15% of the study population has been lost to follow up. The number of subjects lost to follow up is not equally distributed among the cases and controls, most of the subjects who are lost to follow up belong to the non vaccinated group. The study used clinical criteria alone as outcomes. This was not substantiated by laboratory criteria. Hence the presence of invasive pneumococcal disease in subjects with outcomes has not been proved. lxiv There were no validated criteria for admission to the hospital. Hospitalization was not always decided by the investigating examiner. However, there may have been a bias in deciding which patient should have been hospitalized. CONCLUSIONS : 1. The percentage of eligible adult population presenting to Medical OPD who receive Pneumococcal vaccination is very low, currently1.03% [CI (0.93-1.13%)].There is need to increase awareness among practicing physicians to prescribe the correct dose to eligible groups of people. 2. The odds ratio for a patient with outcome (any one of the following- respiratory symptoms, exacerbation of COPD, hospitalization, death) being vaccinated is 0.11 [CI (0.05-0.25)]. This means that Pneumococcal vaccination confers an 89% protective effect against development of total outcomes (p < 0.001). 3. The odds ratio for a patient with symptoms of fever, cough and yellow sputum occurring during the study period being vaccinated is 0.14 [CI (0.06-0.32)] ie. Pneumococcal vaccination gives an 86% protective effect against symptoms of fever, cough and yellow sputum (p < 0.001). 4. The odds ratio for a patient with acute exacerbation of COPD occurring during the study period being vaccinated is 0.19 [CI (0.04-0.99)] showing a protective effect (p=0.04). However, when the patients who have been lost to follow up are also included in the analysis (sensitivity analysis), the protective effect becomes non significant. This tells us that exacerbations of COPD s influenced by multiple factors other than pneumococcal infection. 5. There were 7 hospitalized patients out of which one patient was vaccinated and 6 were not vaccinated. The odds ratio for patients who are hospitalized being vaccinated is 0.12 [CI (0.01-0.99)] which shows a statistically significant association between vaccination status and hospitalization (p= 0.04). 6. 3 vaccinated and 3 non vaccinated patients died during the study period. There was no protective association between Pneumococcal vaccination and death. 7. The main reason for subjects declining vaccination was the cost of the vaccine. 5 out of 77 patients (72%) [CI (61.3-81.5%)] considered cost as the leading reason for non vaccination. The other reasons were that at the time of recruitment, they were not symptomatic (10/77 patients =13%) [CI (5.5-20.5%)] or were not convinced (6/77 patients =8%)[CI(1.8-13.8%)] about the need for vaccination. In 5 out of 77 patients (6%) [CI (0.99-11.9%)], the reason for non vaccination could not be ascertained. 8. The main reasons for doctors’ not prescribing the vaccine were due to oversight and focusing on other medical problems. None of the doctors thought that there was a lack of evidence regarding the protective efficacy of the vaccine. 9. The main patient groups to whom the vaccine was being prescribed were the elderly and patients who had underlying lung diseases. 10. 6 out of 12 doctors (50%) [CI (21.7-78.2%)] were of the opinion that they occasionally prescribed the vaccine whereas 4 out of 12 doctors (33%) [CI (6.7-60%)] said they usually prescribed the vaccine. However, this is probably a misconception as only about 1 % of the eligible population is being vaccinated.
| Item Type: | Thesis (Masters) |
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| Uncontrolled Keywords: | Pneumococcal Vaccine ; Tertiary Care Centre ; India. |
| Subjects: | MEDICAL > General Medicine |
| Depositing User: | Subramani R |
| Date Deposited: | 16 Feb 2018 01:27 |
| Last Modified: | 16 Feb 2018 01:27 |
| URI: | http://repository-tnmgrmu.ac.in/id/eprint/5736 |
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