Table 3.

Multivariable‐Adjusted Hazard Ratios for Time‐Updated Serum Bicarbonate on Mortality in the CRIC Study Using Marginal Structural Models

	Marginal Structural Model Hazard Ratio (95% Confidence Interval)
Death*
Continuous serum bicarbonate	Per 1 mmol/L increase in mean bicarbonate over time*
	1.02 (0.98 to 1.06)
Categorical serum bicarbonate (reference 22 to 26 mmol/L)
Serum bicarbonate <22 mmol/L	1.26 (0.92 to 1.74)
Serum bicarbonate >26 mmol/L	1.36 (1.02 to 1.82)

Total of 3586 participants were included in the model. There were a total of 639 deaths. CRIC indicates Chronic Renal Insufficiency Cohort; eGFR, estimated glomerular filtration rate.

^*The 3 categories of serum bicarbonate, 22 to 26, <22 and >26 mmol/L, had the following distribution of CRIC participants: 2071, 610, and 905, with corresponding 358, 130, and 151 deaths in each group, respectively.

^*Results generated from a Marginal Structural Model with updated mean serum bicarbonate over time. All models are adjusted for age, gender, race/ethnicity, clinical center, eGFR, proteinuria, diabetes, hypertension, cardiovascular disease at baseline, chronic obstructive pulmonary disease, tobacco use, diuretic and alkali medication used, Low Density Lipoprotein, Fibroblast Growth Factor 23, High‐sensitivity C‐reactive protein. In order to evaluate the risk of events for participants with bicarbonate belonging to any category only a certain percent of time, the risk should be multiplied by that percent (ie, if a participant spends 50% of the time with bicarbonate >26 mmol/L, the risk of mortality is 36×0.5=18%).