Table 4.

Univariate associations between baseline factors prior to or at CKD stage and time to entry into subsequent CKD stage

	Patient characteristic	Patients (N)	Events (N)	HR	Lower 95% CI	Upper 95% CI	P
Stage 2 (eGFR<90)	Male, n(%)	81	43	0.80	0.44	1.47	0.5
	Age at PH dx (per 10 years)	81	43	1.11	0.88	1.39	0.4
	Difference b/t Symptom Onset and PH dx (per year)	70	40	1.02	0.98	1.05	0.3
	Age at 1st entry into CKD stage (per decade)	81	43	1.10	0.87	1.40	0.4
	eGFR at 1st entry into CKD stage (per 10 mL/min/1.73 m2)	81	43	0.42	0.27	0.64	<.001
	Nephrocalcinosis, n(%)	81	43	1.21	0.59	2.50	0.6
	Plasma oxalate† (per 1 μmol/L)	20	11	0.96	0.79	1.16	0.7
	BSA adjusted urine oxalate†(per 0.1 mmol/1.73 m2/24 h)	54	31	1.02	0.98	1.05	0.4
Stage 3a (eGFR<60)	Male, n(%)	54	32	0.70	0.34	1.45	0.3
	Age at PH dx (per 10 years)	54	32	1.37	1.07	1.75	0.01
	Difference b/t Symptom Onset and PH dx (years)	52	31	1.05	1.01	1.09	0.01
	Age at 1st entry into CKD stage (per decade)	54	32	1.32	1.08	1.61	0.01
	eGFR at 1st entry into CKD stage (per 10 mL/min/1.73 m2)	54	32	0.75	0.34	1.64	0.5
	Nephrocalcinosis, n(%)	54	32	1.23	0.61	2.47	0.6
	Plasma oxalate† (per 1 μmol/L)	17	7	1.00	0.79	1.27	0.9
	BSA adjusted urine oxalate†(per 0.1 mmol/1.73 m2/24 h)	37	21	0.99	0.97	1.03	0.9
Stage 3b (eGFR<45)	Male, n(%)	32	26	1.20	0.54	2.67	0.7
	Age at PH dx (per 10 years)	32	26	1.23	0.95	1.58	0.1
	Difference b/t Symptom Onset and PH dx (years)	28	23	1.01	0.98	1.05	0.4
	Age at 1st entry into CKD stage (per decade)	32	26	1.29	1.03	1.61	0.03
	eGFR at 1st entry into CKD stage (per 10 mL/min/1.73 m2)	32	26	0.56	0.17	1.85	0.3
	Nephrocalcinosis, n(%)	32	26	0.45	0.19	1.05	0.07
	Plasma oxalate† (per 1 μmol/L)	13	11	1.12	0.99	1.25	0.07
	BSA adjusted urine oxalate†(per 0.1 mmol/1.73 m2/24 h)	21	17	1.03	0.99	1.08	0.1
Stage 4 (eGFR<30)	Male, n(%)	14	11	1.34	0.39	4.64	0.6
	Age at PH dx (per 10 years)	14	11	1.06	0.75	1.49	0.7
	Difference b/t Symptom Onset and PH dx (years)	13	11	0.99	0.94	1.04	0.8
	Age at 1st entry into CKD stage (per decade)	14	11	1.16	0.86	1.57	0.3
	eGFR at 1st entry into CKD stage (per 10 mL/min/1.73 m2)	14	11	0.75	0.21	2.73	0.7
	Nephrocalcinosis, n(%)	14	11	5.30	1.07	26.28	0.04
	Plasma oxalate† (per 1 μmol/L)	8	6	1.062	0.95	1.09	0.6
	BSA adjusted urine oxalate†(per 0.1 mmol/1.73 m2/24 h)	11	9	1.03	0.96	1.12	0.4

Models are fit separately for different CKD stages.

^†Lab values at baseline were defined as occurring between 1 year prior to and up to 1 week after entry into CKD

P-values in bold denote statistical significance at the 0.05 alpha level.

N=number of patients or number of events.

Results were calculated using cox proportional hazards regression.