Table 2.

Predictors of future kidney function decline of patients with ADPKD participating in the water deprivation tests (n=28)

Predictors		Univariable		Multivariable
				Model 1		Model 2
		β	P Value	β	P Value	β	P Value
eGFR, per 10 ml/min per 1.73 m2		0.056	0.69	0.31	0.22
Age, per 10 yr				0.67	0.22
Sex, female versus male				−0.27	0.78
Maximal urine-concentrating capacity, per 10 mOsm/kg		0.041	0.13	0.068	0.03	0.09	0.04
Age, per 10 yr				0.54	0.14	0.30	0.59
Sex, female versus male				−0.25	0.78	−0.03	0.97
eGFR, per 10 ml/min per 1.73 m2						−0.19	0.57
Urine-to-plasma urea ratio, per 1 U		1.66	0.05	3.18	0.002	5.56	<0.001
Age, per 10 yr				0.83	0.03	0.12	0.81
Sex, female versus male				−0.79	0.36	−0.56	0.48
eGFR, per 10 ml/min per 1.73 m2						−0.71	0.04

Associations of baseline eGFR, measured maximal urine-concentrating capacity, and early morning fasting spot urine-to-plasma urea ratio with subsequent rate of kidney function decline were assessed with use of mixed-model analysis. Urine-to-plasma urea ratio was natural log-transformed to attain normal distribution. Maximal urine-concentrating capacity was defined as the plateau of highest urine osmolality that was reached after a prolonged water deprivation test. In these analyses, two patients were excluded because of V2 receptor antagonist (tolvaptan) use longer than 6 months during follow-up. ADPKD, autosomal dominant polycystic kidney disease.