Table 4.
Additional analysis (patients who were lost to follow up (18 in total) were assumed not recovered at 7 days)
| Group | n | Odds ratio (95% CI) | NNT (benefit) (95%CI)a | NNT (harm)a (95%CI)b |
|---|---|---|---|---|
| All patients | 181 | 1.17 (0.64 to 2.13) | 25.85 (NNT[harm] 9.09 to∞ to NNT[benefit] 5.70) | – |
| Culture positive patients | 58b | 2.69 (0.91 to 7.98) | 4.15 (NNT[harm] 45.45 to∞ to NNT[benefit] 2.21) | – |
| Culture negative patients | 121b | 0.76 (0.36 to 1.59) | – | 14.78 (NNT[harm] 3.97 to∞ to NNT[benefit] 9.52) |
a
The odds ratios obtained from the regression analysis were converted into relative risks. The relative risks were converted into risk differences and numbers needed to treat using the clinical outcome rate in the placebo group as the background risk. The numbers needed to benefit and the numbers needed to harm and their 95% confidence intervals are presented as recommended by Altman.23
b
The culture results of two patients were missing. P-value of the interaction term is 0.05. NNT (benefit) = number needed to benefit. NNT (harm) = number needed to harm.