Table 4 Analysis of timing and site of swabs.
From: Antenatal screening for Group B Streptococcus: A diagnostic cohort study
Timing (36 v 32 weeks) | Site (Either Lower Vaginal or Perianal vs Lower Vaginal Swab alone) | |||||
|---|---|---|---|---|---|---|
Difference (36 – 32) | 95% Confidence Interval | p-value | Difference (Either vs LVS) | 95% Confidence Interval | p-value | |
Sensitivity | 8.8% | (1.2%, 16.3%) | 0.023* | 8.2% | (4.6%, 11.7%) | <0.001† |
Specificity | 0.6% | (-1.2%, 2.5%) | 0.493 | -1.8% | (-2.6%, -0.9%) | <0.001§/P > |
Negative Predictive Value | 2.3% | (0.3%, 4.3%) | 0.026* | 2.0% | (1.0%, 3.0%) | <0.001† |
Positive Predictive Value | 3.6% | (-2.8%, 9.9%) | 0.269 | -3.1% | (-5.8%, -0.5%) | 0.019§/P > |
Likelihood Ratio + | 1.62 | (-2.69, 5.92) | 0.462 | -1.59 | (-3.68, 0.49) | 0.134 |
Likelihood Ratio - | -0.09 | (-0.18, -0.01) | 0.021* | -0.08 | (-0.12, -0.04) | <0.001† |
Diagnostic Odds Ratio | 14.3 | (-8.06, 36.8) | 0.210 | 3.63 | (-4.99, 12.2) | 0.409 |