Table 4.

Possible determinants of kidney function reserve capacity and filtration fraction in patients with ADPKD and healthy controls

VariablesKidney Function Reserve Capacity (%)Filtration Fraction (%)
UnivariableMultivariableMultivariable
Nβ [95% CI]P Valueβ [95% CI]P Valueβ [95% CI]P Valueβ [95% CI]P Value
ADPKD
 Men versus women150−1.5 [−4.7 to 1.7]0.34−0.8 [−4.6 to 3.1]0.70−0.7 [−2.1 to 0.7]0.31−1.1 [−2.7 to 0.5]0.17
 Measured GFR, per 10 ml/min per 1.73 m21501.0 [0.5 to 1.5]<0.0010.8 [0.05 to 1.6]0.040.6 [0.4 to 0.9]<0.0010.6 [0.3 to 0.9]<0.001
PKD2 versus PKD1 mutation124−0.4 [−4.6 to 3.7]0.84−0.4 [−4.8 to 4.0]0.860.1 [−1.8 to 2.0]0.95−0.2 [−2.0 to 1.6]0.85
 htTKV (per doubling)143−2.4 [−3.9 to −0.8]0.003−1.6 [−3.8 to 0.6]0.15−0.4 [−1.1 to 0.3]0.250.6 [−0.3 to 1.5]0.18
 RAAS inhibitor use (yes versus no)150−1.9 [−5.3 to 1.5]0.260.9 [−3.3 to 5.0]0.68−2.4 [−3.9 to −1.0]0.001−1.3 [−3.0 to 0.4]0.12
 BMI, per kg/m21500.1 [−0.3 to 0.4]0.720.2 [−0.2 to 0.6]0.250.1 [−0.1 to 0.2]0.470.0 [−0.1 to 0.2]0.42
 Protein intake, per 10 g/24 h1470.1 [−0.6 to 0.8]0.740.2 [−0.7 to 1.1]0.630.2 [−0.1 to 0.5]0.30−0.0 [−0.4 to 0.3]0.81
 Sodium intake, per 10 mmol/24 h1470.1 [−0.2 to 0.3]0.71−0.1 [−0.4 to 0.3]0.730.2 [0.1 to 0.3]<0.0010.1 [0.0 to 0.3]0.05
Healthy controls
 Men versus women150−0.1 [−2.9 to 2.7]0.96−0.2 [−3.2 to 2.8]0.890.1 [−1.1 to 1.4]0.830.1 [−1.3 to 1.5]0.91
 Measured GFR, per 10 ml/min per 1.73 m2150−1.5 [−2.3 to −0.6]0.001−1.5 [−2.4 to −0.6]0.0020.5 [0.1 to 0.9]0.020.5 [0.1 to 0.9]0.03
 RAAS inhibitor use (yes versus no)150−8.8 [−20.7 to 3.2]0.15−7.8 [−20.0 to 4.5]0.21−0.4 [−6.0 to 5.1]0.88−1.4 [−7.1 to 4.3]0.63
 BMI, per kg/m21500.2 [−0.3 to 0.6]0.470.03 [−0.4 to 0.5]0.910.0 [−0.2 to 0.2]0.840.1 [−0.1 to 0.3]0.42
 Protein intake, per 10 g/24 h1410.1 [−0.4 to 0.6]0.630.02 [−0.6 to 0.6]0.95−0.2 [−0.4 to 0.1]0.17−0.2 [−0.5 to 0.0]0.07
 Sodium intake, per 10 mmol/24 h1420.1 [−0.1 to 0.3]0.530.1 [−0.1 to 0.3]0.310.0 [−0.1 to 0.1]0.750.0 [−0.1 to 0.1]0.50
  • βs with 95% CIs and P values were calculated using linear regression analysis with pairwise exclusion of missing data. Dependent variable is kidney function reserve capacity or filtration fraction; independent variables are sex, measured GFR, PKD mutation, htTKV, use of RAAS inhibitors, BMI, protein intake, and sodium intake. ADPKD, autosomal dominant polycystic kidney disease; 95% CI, 95% confidence interval; PKD, polycystic kidney disease; htTKV, height-adjusted total kidney volume; RAAS, renin-angiotensin-aldosterone system; BMI, body mass index.