Table 1.
Exploratory Evidence for Detecting Time-Dependent Confounding Among Explanatory Variables
| Criterion and Weighting (points assigned for criterion) | Pairs of MICU Treatments Being Examined for Time-Dependent Confounding | ||
|---|---|---|---|
| Fentanyl and Haloperidol | Fentanyl and Intubation | Haloperidol and Intubation | |
| Similar Trends in Plots In Either Temporal Direction? (1 point) | Yes | Yes | No |
| Significant Correlation ≥ 40%? (1 point) | Yes | Yes | Yes |
| Cross-Correlation Function Significant in Either Temporal Direction? (2 points) | No | No | No |
| Significant Association in GEE Regression of First Variable on Lag of Second? (3 points) | Yes | Yes | No |
| Significant Association in GEE Regression of Second Variable on Lag of First? (3 points) | No | Yes | No |
| Total Point Score where higher indicates greater evidence of time-dependent confounding (0 to 10 points) | 5 points | 8 points | 1 point |
| Qualitative Weight of Evidence for Time-Dependent Confounding | Moderate (4 – 5 points) | High (≥ 6 points) | Low (≤ 3 points) |
MICU = medical intensive care unit.
GEE = generalized estimating equations.