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Table 2 Patients with complete and incomplete follow-up data stratified for CKD onset; values are numbers (%) unless indicated otherwise

From: An external validation of models to predict the onset of chronic kidney disease using population-based electronic health records from Salford, UK

Parameters

No CKD

CKD

Patients with complete follow-up

Patients with incomplete follow-up

 

Missing

 

Missing

 

Missing

Included patients

156,615

None

172,361

None

6038

None

Died before developing CKD

719 (0.5)

None

6941 (4)

None

/

None

Follow-up (mean, SD)

5.6 (0.2)

None

5.4 (0.7)

None

2.6 (1.7)

None

Age (mean, SD)

42.1 (16.7)

None

42.7 (17.3)

None

70.3 (12.5)

None

Female sex

82,883 (52.9)

None

89,389 (51.9)

None

3452 (57.2)

None

Townsend index (mean, SD)e

1.6 (3.5)

2900 (1.9)

1.6 (3.4)

3244 (1.9)

1.4 (3.4)

47 (0.8)

Ethnicity

Not recorded

55,586 (35.6)

Not applicabled

61,220 (35.6)

Not applicabled

2014 (33.4)

Not applicabled

White

90,443 (57.8)

99,243 (57.7)

3889 (64.5)

Other

10,586 (6.8)

11,898 (6.9)

135 (2.2)

Smokinge

Non-smoker

66,769 (48.8)

19,901 (12.7)

72,137 (48.4)

23,296 (13.5)

2167 (37.7)

292 (4.8)

Ex-smoker

29,980 (21.9)

33,097 (22.2)

2475 (43.1)

Light smoker (1–9 cg/day)

11,072 (8.1)

12,128 (8.1)

344 (6)

Moderate smoker (10–19 cg/day)

16,951 (12.4)

18,472 (12.4)

413 (7.2)

Heavy smoker (≥ 20 cg/day)

11,942 (8.7)

13,231 (8.9)

347 (6)

BMI, kg/m2 (mean, SD)e

26.6 (6)

33,717 (21.5)

28 (6.1)

38,628 (22.4)

28.4 (6)

518 (8.6)

Diastolic blood pressure, mmHg (mean, SD)e

76.9 (9.8)

75,616 (48.3)

78.9 (10.2)

85,075 (49.4)

75.8 (10.2)

1164 (19.3)

Systolic blood pressure, mmHg (mean, SD)e

128.2 (15.8)

75,602 (48.3)

130.5 (16.7)

85,058 (49.3)

136.3 (16.7)

1166 (19.3)

eGFR, mL/min/1.73 m2 (mean, SD)

83.7 (9.4)

118,912 (75.9)

82.5 (9.4)

131,103 (76.1)

69.4 (11.3)

1828 (30.3)

Hb, g/dLe

13.9 (1.6)

110,723 (70.7)

13.8 (1.6)

122,430 (71)

13.4 (1.7)

2530 (41.9)

Proteinuriaa,b

751 (0.5)

149,234 (95.3)

18 (0.2)

164,097 (95.2)

236 (3.9)

4665 (77.3)

Quantitative albuminuriab,c

129 (0.1)

152,266 (97.2)

4 (0)

167,482 (97.2)

62 (1)

5167 (85.6)

HDL cholesterol levelb, mg/dL (mean, SD)

25.9 (7.9)

122,477 (78.2)

26.7 (7.9)

135,066 (78.4)

25.7 (7.8)

2413 (40)

  1. BMI, body mass index; cg, cigarettes; CKD, chronic kidney disease; eGFR, estimated glomerular filtration rate; HDL, high-density lipoprotein; MDRD, modification of diet in renal disease; SD, standard deviation
  2. aAlbumin:creatinine ratio >30 mg/mmol or albumin concentration >200 mg/L, or diagnostic code
  3. bVariable excluded as predictor from external validation due to >70 % missing values
  4. cAlbumin:creatinine ratio >30 mg/mmol
  5. dPatients without recorded ethnicity were considered as white (see Methodssection)
  6. eMultiple imputation applied to missing values
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