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Table 1 Comparison of conventional smears and smears prepared from bleach-sedimented sputum

From: Evaluation of bleach-sedimentation for sterilising and concentrating Mycobacterium tuberculosis in sputum specimens

  Conventional smears Smears prepared from bleach-sedimented sputum * p-value
Acid-fast bacilli counts per 100 microscopy fields, geometric mean (95% CI) 346 (139-862) 166 (68-406) 0.02
Slide-reading time, arithmetic mean minutes (standard error of the mean) 11.2 (0.92) 9.6 (0.69) 0.03
Inter-observer agreement, correlation coefficient (r) 0.991 0.997 -
Correlation between concentrating effect of bleach-sedimentation and acid-fast bacilli counts, correlation coefficient (r) -0.46 0.02
Correlation between concentrating effect of bleach-sedimentation and volume of the sputum specimen, correlation coefficient (r) -0.13 0.7
Concentrating effect of bleach-sedimentation comparing salivary versus mucoid sputum specimens - 0.3
Concentrating effect of bleach-sedimentation comparing moderately versus very experienced microscopists - 0.6
  1. * False-negative (zero) microscopy readings by a single microscopist for 3 strongly positive smears prepared from bleach-sedimented specimens were excluded when calculating these data (see text and Figure 5).