Table 2.

Criteria for classifying trajectories of eGFR decline according to analytic approach

Classification of trajectory if criterion met	Criterion	Classification of trajectory if criterion not met
Spline regression method
Nonlinear	Linear model is rejected in favor of spline model at P < 0.05 with partial F test.	Linear
Clinically consequential nonlinearity	Linear model rejected and linear projection of time to reach eGFR = 10 mL/min/1.73 m2 misses the observed time of ESRD by 1 year or more.	Clinically inconsequential nonlinearity
Acceleration	Clinically consequential nonlinear trajectory and the slope of the second spline segment is steeper than the first.
Deceleration	Clinically consequential nonlinear trajectory and the slope of the first spline segment is steeper than the second.
Bayesian method
Nonlinear	Any eGFR difference between the smoothed trajectory and the line fitted to it is ≥15 mL/min/1.73 m2.	Linear
Bayesian method with criteria of linearity proposed in AASK study
Nonlinear	Mean slope for the half of the follow-up months with faster decline differs from the mean slope for the half with slower yearly decline >3 mL/min/1.73 m2.	Linear