Effect on Postoperative Pain | Estimated Risk or Estimated Score/value with Placebo | Absolute Reduction in Risk or Reduction in Score/value with Dexamethasone | Relative Effect (95% CI) | Comments |
---|---|---|---|---|

Standardized mean difference (SMD) | The pain score in the dexamethasone groups was on average 0.79 SD (1.41 to 0.17) lower than in the placebo groups | — | As a rule to thumb, 0.2 SD represents a small difference, 0.5 a moderate, and 0.8 a large. | |

Natural units (converted from SD units) | Mean scores with placebo ranged from 43 to 54 | Mean scores in the dexamethasone groups was on average 8.1 (1.8 to 14.5) lower | — | The MID on the 0 to 100 pain scale is about 10. Two possible statistical approaches, one relying on the SMD and the other on direct conversion of all instruments to units of the most familiar instrument. |

Dichotomizing using “substantial postoperative pain” vs other | 20 per 100 | Difference in proportion achieving an important improvement is 0.15 (0.19 to 0.04) | RR = 0.25 (0.05 to 0.75) | Two possible statistical approaches, one going directly from SMD to risk difference and the other using the MID to calculate risk differences in individual studies and then pooling across studies. |

Ratio of means | 28.1 | 3.7 lower pain score (6.1 to 0.6) | ROM = 0.87 (0.78 to 0.98) | The ROM is the weighted average of the mean pain score in the treatment groups divided by the mean pain score in placebo. |

MID units | The pain score in the dexamethasone groups was on average 0.40 (0.74 to 0.07) MID units less than placebo | An effect of less than half the MID difference suggests a small or very small effect. |

MID: minimally important difference; RR: risk ratio.