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The BCG controversy. A methodological and statistical reappraisal.
JAMA
|May 6, 1983
Summary
BCG vaccination for tuberculosis shows high efficacy when trials have strong methodology and statistical power. Methodological flaws and insufficient statistical precision in some studies may explain conflicting results on BCG
Area of Science:
- Immunology
- Infectious Diseases
- Clinical Trials
Background:
- BCG vaccination against tuberculosis has been used for over 50 years.
- Conflicting results from eight major controlled trials have led to ongoing controversy regarding its efficacy.
Purpose of the Study:
- To investigate the methodological and statistical quality of major BCG vaccination trials.
- To resolve the controversy surrounding BCG vaccine efficacy against tuberculosis.
Main Methods:
- Systematic review and critical analysis of scientific and statistical quality of eight major controlled trials.
- Evaluation of bias in vaccine allocation and tuberculosis detection.
- Assessment of confidence intervals for protective efficacy.
Main Results:
- Adequate demonstration of unbiased tuberculosis detection was limited to trials reporting >=75% protective efficacy.
- Trials with low reported efficacy often had wide confidence intervals, not excluding high efficacy.
- Trials reporting high efficacy demonstrated narrow confidence intervals, excluding low efficacy.
- Higher methodological quality and statistical precision correlated with higher reported efficacy.
Conclusions:
- BCG vaccination likely confers a high degree of protection against tuberculosis.
- Methodological limitations and inadequate statistical power in some trials may explain conflicting efficacy data.
- High-quality trials suggest BCG is an effective tuberculosis vaccine.