7. Optimal information size calculation (minimal clinically relevant difference) for GRADE‐relevant continuous outcomes.
|
EE [95% CI], P value, I2, n |
OIS_minimal clinically relevant difference1 | |||||
| mean1 | mean2 | SDlargest | OIS | evidence | ||
| 1.1 Satisfaction with pain relief | 2.11 [0.72, 3.49], 0.003, 93%, 216 |
7 | 6 | 2.22 | 208 | evidence of effect (intervention) |
| best low risk of bias study: Ng 2011 | ||||||
| 1.11 Pain intensity 'early' | ‐1.58 [‐2.69, ‐0.48], 0.005, 89%, 180 |
25.6 | 35.6 | 26.6 | 298 | absence of evidence |
| best low risk of bias study: Ng 2011 | ||||||
| 2.13 Pain intensity 'early' | ‐0.51 [‐1.01, ‐0.00], 0.05, 52%, 215 | 5.282 | 6.282 | 2.414 | 246 | absence of evidence |
| best low risk of bias study: Douma 2010 | ||||||
| 3.1 Satisfaction with pain relief | ‐0.22 [‐0.40, ‐0.04], 0.02, 52%, 2135 |
8.1 | 9.1 | 1.5 | 96 | evidence of effect (control) |
| best study (high risk): Stocki 2014 | ||||||
| 3.16 Pain intensity 'early' | 0.57 [0.31, 0.84], < 0.0001, 0%, 235 |
3.3 | 2.3 | 3.3 | 458 | absence of evidence |
| best study (high risk): Stocki 2014 | ||||||
The summary statistics for the GRADE‐relevant continuous outcomes was SMD (standardised mean difference). The TSA software (version 0.9 Beta) did not support trial sequential analysis of SMD. Therefore, we conducted OIS (optimal information size) calculations (http://stat.ubc.ca/˜rollin/stats/ssize/n2.html) which corresponds to a sample size calculation for an individual trial with the following general assumptions on α = 0.05 and ß = 0.10 (power = 90%).
1The assumed minimal clinically relevant difference was 1.0 cm (10 mm) on a VAS 0 to 10 cm (0 to 100 mm) scale. The mean2 was derived from the control group (low risk of bias (best) trial).
Abbreviations:
EE [95% CI]: estimated effect with 95% confidence interval; mean1: intervention group; mean2: control group; n: number of participants; SDlargest: largest standard deviation of the pooled studies was assumed