Fig 1.
Decision tree for hazard ratio extraction: Flow chart to determine which hazard ratio estimate to use based on data provided in manuscript.
Table 1.
Determination of reference group for hazard ratio: Table to assist extractors in identifying reference group, determining need to invert hazard ratios.
Fig 2.
Simulations to verify correct implementation of Guyot algorithm: Visual illustration of simulations explored for validation of Guyot algorithm.
Details can be found in S2 Appendix.
Table 2.
Comparison of hazard ratios Method 1 through 4.
Comparison showing information required for calculation of hazard ratio using various methods and resulting hazard ratio and 95% confidence interval.
Fig 3.
Kaplan-Meier curve worked example: Example data for Method 3 Guyot algorithm and worked example.
Panel A is a graph that might appear in a publication. Panel B shows the “digitized” version with time and KM points, and panel C shows the re-constructed individual patient data using the digitization and n at risk as input. See S1 Appendix for full R code.
Table 3.
Worked example using Method 2: Hazard ratio calculated using event counts.
HR = Hazard Ratio, CI = Confidence Interval, eq. = equation, est. = estimated, Vr is the inverse variance of the log hazard ratio for the robotic group, OTotal is the total number of events in the robotic plus the comparison group, “Ln” denotes the natural logarithm (loge), Φ-1 is the inverse of the standard normal distribution, and the p-value is assumed to be 2-sided and from the log-rank test if not otherwise stated. Because p-values were assumed to be two-sided, manual assignment of direction was adjusted by multiplying the term by -1 or 1 so that the result was negative when survival in the robotic group was higher/better and positive when survival in the robotic group was lower/worse.
Table 4.
Worked example using Method 4b: Hazard ratio calculated using median survival estimates.
HR = Hazard Ratio, CI = Confidence Interval, eq. = equation, “Ln” denotes the natural logarithm (loge).