Table 1—

Comparison of paired culture results obtained by alternative sputum collection methods among 78 patients with culture-proven pulmonary tuberculosis

Method 1Method 2Both negativeBoth positivePositive in method 1 onlyPositive in method 2 only% difference between paired proportions (95% CI)
First unsupervised sputumSecond unsupervised sputum361818 (23.1)6 (7.7)15.4 (3.1–27.7)
Induced sputumSupervised sputum83824 (30.8)8 (10.3)20.5 (6.3–34.7)
Two unsupervised and one supervised sputaTwo unsupervised sputa184218 (23.1)0 (0)23.1(12.4–33.7)
Two unsupervised, one supervised and one induced sputaTwo unsupervised and one supervised sputa16017 (21.8)0 (0)21.8 (11.4–32.2)
Two unsupervised, one supervised and one induced sputaTwo unsupervised sputa14235 (44.9)0 (0)44.9 (30.0–59.7)
  • Data are presented as n or n (%), unless otherwise stated, where n refers to frequency of paired results and % is calculated based on 78 pairs and is shown in brackets for unmatched results only. CI: confidence interval. The second unsupervised sputum was significantly inferior to the first unsupervised. Induced sputum significantly outperformed supervised sputum. Adding one specimen each of supervised and induced sputum to two unsupervised specimens increased culture yield significantly.