Table 2.

Associations of Baseline Fitness With Incident CKD^a in Full Sample and Fitness Groups

Association of fitness	Model 1	Model 2	Model 3	Model 4	Model 5
	HR (95% CI)	HR (95% CI)	HR (95% CI)	HR (95% CI)	HR (95% CI)
Duration with CKD
Fitness per 1 minute lower duration	1.13 (1.06,1.21)	1.17 (1.07, 1.27)	1.16 (1.06,1.26)	1.14 (1.04,1.25)	1.14 (1.04,1.25)
Groups with CKD
Low vs high fitness (ref)	3.76 (2.38, 5.94)	2.70 (1.65, 4.40)	2.57 (1.56, 4.24)	2.42 (1.40, 4.10)	2.44 (1.42, 4.20)
Low vs moderate fitness (ref)	2.35 (1.56, 3.53)	1.98 (1.31, 3.00)	1.93 (1.27, 2.93)	1.83 (1.18, 2.83)	1.83 (1.19, 2.85)
Moderate vs high fitness (ref)	1.60 (1.02, 2.52)	1.37 (0.86, 2.18)	1.33 (0.83, 2.13)	1.32 (0.82,2.10)	1.34 (0.83,2.13)

Notes: Boldface indicates statistical significance (p<0.05). Model 1: Unadjusted. Model 2: Model 1 + gender, race, age, maximal education throughout study, and field center. Model 3: Model 2 + time varying healthy eating index score, smoking status, alcohol intake. Model 4: Model 3 + time varying BMI, systolic BP, and fasting glucose. Model 5: Model 4+ baseline eGFR. Low fitness: bottom lowest gender-specific quintile (bottom 20%); Moderate fitness: quintiles 2–3 (middle 20%–60%); High fitness: quintiles 4–5 (top >60%).

^aChronic Kidney Disease (CKD) defined as eGFR <60 mL/min/1.73m².

HR, hazard ratio.