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Comparison of different methods for adjusting for confounding in a Cox regression using simulated data in stata

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Simulation of Different Methods of Adjusting for confounders in a Cox Regression

Stata files each produce 10000 simulated datasets (N=3605) containing:

  • confounder 1 (binary)
  • confounder 2 (continuous)
  • confounder 3 (binary)
  • exposure group 1 (true hazards ratio: 1.5; N=463)
  • exposure group 2 (true hazards ratio: 1.5; N=322)
  • outcome variable (binary)

1_simulate_data_unconfounded.do produces unconfounded datasets, where confounders 1-3 are not associated with exposure groups.

In each do file, a cox model is run to obtain estimated coefficients for each of the 10000 simulated models. A different method of controlling for confounding is implemented for each:

  • 2_weighted_yoshida.do - the weighting method described in this paper: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5378668/pdf/nihms845429.pdf
  • 3_simulation_control_in_model.do - adjusting for all 3 confounders
  • 4_simulation_pair_wise_matchingl.do - separate models are run to compare exposure group 1 vs controls, exposure group 2 vs controls. Exposure propensity scores are estimated using logistic regression with the dependent variables as confounder 1-3. Exposed are matched to unexposed controls 1:2 using nearest neighbour matching without replacement.
  • 5_simulation_pair_wise_andcontrol - same as previous, except confounders are also controlled for in Cox model.

Plotting results

density_plots_estimates.R imports the outputs from do files 2, 3 and 4 are imported and plotted

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Comparison of different methods for adjusting for confounding in a Cox regression using simulated data in stata

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