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Table 1 Comparison of patient characteristicsa

From: Selection bias and subject refusal in a cluster-randomized controlled trial

Characteristic

Intervention Sites

Control Sites

Enrolled in Intervention vs. Control

Declined in Intervention vs. Control

genmod model or mixed model

A:

B:

C:

D:

E:

F:

H:

I:

G:

Consented (n = 147)

Declined (n = 89)

P-value between A and B

Consented (n = 150)

Declined (n = 75)

P-value between D and E

P-value between A and D

P-value between B and E

Study group and consent as independent variables

Mean Age (±SD)

63.2 (±9.0) (n = 147)

65.2 (±8.9) b (n = 86)

0.099

63.8 (±8.0) (n = 150)

64.1 (±8.6) d (n = 73)

0.801

0.547

0.424

0.8963

0.1013

% Female

44.2% (65/147)

37.9% c (33/87)

0.346

53.3% (80/150)

42.7% (32/75)

0.131

0.116

0.540

0.1855

0.0338

% with uncontrolled diabetes

61.9% (91/147)

70.8% (63/89)

0.165

63.3% (95/150)

46.7% (35/75)

0.017

0.799

0.0017

0.6786

0.3105

Mean A1c

8.7 (±1.1) (n = 91)

9.1 (±1.5) (n = 63)

0.154

8.8 (±1.1) (n = 95)

8.9 (±1.3) (n = 35)

0.806

0.669

0.523

0.9187

0.1733

% with uncontrolled hyperlipidemia

35.4% (52/147)

40.5% (36/89)

0.435

48.7% (73/150)

42.7% (32/75)

0.395

0.020

0.774

0.1139

0.8094

Mean LDL (±SD)

145.0 (±35.2) (n = 52)

140.4 (±26.1) (n = 36)

0.502

144.8 (±26.9) (n = 73)

147.3 (±33.4) (n = 32)

0.686

0.970

0.342

0.7408

0.7349

% with uncontrolled hypertension

59.9% (88/147)

52.8% (47/89)

0.288

48.0% (72/150)

56.0% (42/75)

0.258

0.040

0.683

0.3855

0.8320

Mean Systolic BP (±SD)

152.1 (±15.9) (n = 88)

151.8 (±15.5) (n = 47)

0.918

149.0 (±10.7) (n = 72)

149.6 (±13.6) (n = 42)

0.818

0.146

0.470

0.3601

0.6283

Mean Diastolic BP (±SD)

83.4 (±11.8) (n = 88)

79.7 (±12.3) (n = 47)

0.084

84.2 (±11.1) (n = 72)

86.6 (±13.1) (n = 42)

0.297

0.689

0.012

0.2396

0.3901

% Current Smoker

29.3% (43/147)

20.2% (18/89)

0.125

22.7% (34/150)

25.3% (19/75)

0.657

0.195

0.436

0.4250

0.0805

  1. aMean values are shown as mean (± standard deviation). Percentage values are shown as percent of patients with characteristic out of total number of patients in subgroup
  2. bMissing age information for three subjects
  3. cMissing gender information for two subjects
  4. dMissing age information for two subjects
  5. Bolded value for females is the only significant value when controlling for random clinic effects