Table 1 Clinical characteristics of the patients included in the development sample (DS) and in the temporary validation sample (TVS).

General characteristics

 Male, n (%)

256 (43.9)

34 (43.6)

0.957

 Age (years), \(\:\stackrel{-}{x}\) ± SD

M (Q₁-Q₃)

46.3 ± 14.4

45.9 (35.6–57)

48.7 ± 14.8

48 (38–59)

0.184

 Weight (Kg), \(\:\stackrel{-}{x}\) ± SD

M (Q₁-Q₃)

77.6 ± 20.5

76 (63–88)

77.8 ± 16

76.4 (66–89)

0.941

 Height (m), \(\:\stackrel{-}{x}\) ± SD

M (Q₁-Q₃)

1.66 ± 0.1

1.65 (1.58–1.73)

1.66 ± 0.1

1.66 (1.6–1.71)

0.836

 BMI (Kg/m²), \(\:\stackrel{-}{x}\) ± SD

M (Q₁-Q₃)

28.1 ± 6.7

26.7 (23.8–30.9)

28.4 ± 5.5

27.3 (24.6–32)

0.697

Comorbidities

 Obesity, n (%)

175 (30)

26 (37.1)

0.222

 High blood pressure, n (%)

204 (35.2)

20 (25.6)

0.095

 Diabetes, n (%)

58 (9.9)

7 (9)

0.786

 Single Kidney, n (%)

39 (6.7)

4 (5.1)

0.600

Drugs

 ACEI-ARBs, n (%)

173 (29.8)

17 (21.8)

0.142

Reason for requesting GFR measurement

 Candidate donation, n (%)

387 (66.4)

59 (75.6)

0.142

 Suspected CKD, n (%)

181 (31.1)

19 (24.4)

 Other, n (%)

15 (2.6)

0

Laboratory analysis

Creatinine (mg/dl), \(\:\stackrel{-}{x}\) ± SD

M (Q₁-Q₃)

1.08 ± 0.86

0.84 (0.68–1.09)

1.11 ± 0.58

0.93 (0.82–1.17)

0.709

 Urea (mg/dl), \(\:\stackrel{-}{x}\) ± SD

M (Q₁-Q₃)

39.6 ± 30.6

30.5 (23.5–41.3)

39.5 ± 30.9

29.9 (24.2–39.5)

0.972

 Albumin (g/dl), \(\:\stackrel{-}{x}\) ± SD

M (Q₁-Q₃)

4.20 ± 0.47

4.26 (3.99–4.49)

4.29 ± 0.52

4.36 (4.06–4.58)

0.193

 mGFR (ml/min/1.73 m²), \(\:\stackrel{-}{x}\) ± SD

M (Q₁-Q₃)

91.1 ± 36.2

95.5 (69.9-117.3)

86.2 ± 32.9

89.5 (72.4-116.2)

0.230

 Ranges of the mGFR, n (%)

0.135

  ≥ 90 ml/min/1.73 m²

336 (57.6)

36 (46.1)

  60–89 ml/min/1.73 m²

132 (22.6)

28 (35.9)

  30–59 ml/min/1.73 m²

66 (11.3)

7 (9)

  15–29 ml/min/1.73 m²

26 (4.5)

4 (5.1)

  < 15 ml/min/1.73 m²

23 (4)

3 (3.9)