Table 1.

Bias in Estimates of the Causal Direct Effect of Depression in Early, Mid-, and Late Life on Stroke Risk Under the Accumulation Model Using Conventional Regression Versus Inverse Probability Weighting in the Presence or Absence of Time-Varying Confounding by Alcohol Use Disorder^a

	Estimated Effect (Log RR) of Depression on Stroke Risk
	Conventional Regression						Inverse Probability Weighting
Type of Magnitude Change and Scenario No.	Early-Life Depression ( )	% Bias b	Midlife Depression ( )	% Bias	Late-Life Depression ( )	% Bias	Early-Life Depression ( )	% Bias	Midlife Depression ( )	% Bias	Late-Life Depression ( )	% Bias
Varying the magnitude of the effect of AUD on stroke
1. No confounding	0.69	0	0.69	0	0.69	0	0.69	0	0.69	0	0.69	0
2. Moderate positive confounding	0.58	−16	0.58	−16	0.69	0	0.69	0	0.69	0	0.69	0
3. Strong positive confounding	0.51	−26	0.51	−26	0.69	0	0.69	0	0.69	0	0.69	0
4. Negative confounding	0.81	17	0.81	17	0.69	0	0.69	0	0.69	0	0.69	0
5. Greater confounding earlier in life	0.51	−26	0.58	−16	0.69	0	0.69	0	0.69	0	0.69	0
6. Greater confounding later in life	0.58	−16	0.51	−26	0.69	0	0.69	0	0.69	0	0.69	0
Varying the magnitude of the effect of depression on AUD
7. No effect of depression on AUD	0.69	0	0.69	0	0.69	0	0.69	0	0.69	0	0.69	0
Unmeasured confounding of both AUD and stroke
8. Moderate positive unmeasured confounder of AUD and stroke	0.62	−10	0.58	−16	0.69	0	0.68	−1	0.69	0	0.69	0

Abbreviations: AUD, alcohol use disorder; RR, risk ratio.

^a Data were generated to mimic the effect of depression on stroke under the accumulation model: The true direct effect of depression at each time point doubled the odds of stroke, and depression increased the odds of depression at the subsequent time point by 50%. Data were generated with 10,000 replications and 100,000 people in each sample.

^b Percent bias = [(average of 10,000 estimated effect − true effect of 0.69)/true effect of 0.69] × 100.