TABLE 2.
Characteristics of study participants by clinical center
| Characteristic | Baltimore clinic | Houston clinic | Combined | P value1 |
| n2 | 120 | 185 | 305 | |
| Sex distribution [n (%)] | 0.086 | |||
| Men | 60 (50) | 74 (40) | 134 (44) | |
| Women | 60 (50) | 111 (60) | 171 (56) | |
| Racial distribution [n (%)] | <0.00013 | |||
| White | 89 (74) | 122 (66) | 211 (69) | |
| African American | 28 (23) | 29 (16) | 57 (19) | |
| Hispanic | 1 (1) | 23 (12) | 24 (8) | |
| Other | 2 (2) | 11 (6) | 13 (4) | |
| Age (y) | 61.9 ± 5.34 | 60.7 ± 5.5 | 61.1 ± 5.5 | 0.058 |
| Age distribution [n (%)] | 0.247 | |||
| 45–55 y | 13 (11) | 32 (17) | 45 (15) | |
| 56–65 y | 79 (66) | 118 (64) | 197 (65) | |
| 66–75 y | 28 (23) | 35 (19) | 63 (21) | |
| Systolic blood pressure (mm Hg) | 132 ± 15 | 135 ± 18 | 133 ± 17 | 0.127 |
| Diastolic blood pressure (mm Hg) | 73 ± 9 | 69 ± 9 | 71 ± 9 | 0.0001 |
| Weight (kg) | 103 (91, 116)5 | 102 (90, 116) | 102 (90,116) | 0.689 |
| Height (cm) | 171 ± 10 | 169 ± 10 | 170 ± 10 | 0.023 |
| BMI (kg/m2) | 35.7 ± 6.0 | 36.6 ± 6.5 | 36.3 ± 6.3 | 0.249 |
| Waist circumference (cm) | 114 ± 13 | 116 ± 14 | 115 ± 14 | 0.344 |
| Diabetes duration (y) | 6.8 ± 5.9 | 7.0 ± 6.6 | 6.9 ± 6.4 | 0.800 |
| Medications [n (%)] | ||||
| Insulin | 17 (14) | 38 (21) | 55 (18) | 0.157 |
| Oral hypoglycemic agent | 81 (68) | 148 (80) | 229 (75) | 0.014 |
| Statin | 64 (53) | 95 (51) | 159 (52) | 0.735 |
| Plasma and serum variables | ||||
| Plasma cholesterol (mmol/L) | 4.86 (4.32, 5.59) | 4.81 (4.06, 548) | 4.84 (4.16, 5.53) | 0.309 |
| LDL cholesterol (mmol/L) | 2.84 (2.35, 3.44) | 2.84 (2.25, 3.26) | 2.84 (2.30, 3.34) | 0.297 |
| HDL cholesterol (mmol/L) | 1.11 (0.96, 1.42) | 1.14 (0.96, 1.32) | 1.14 (0.96, 1.34) | 0.296 |
| non–HDL cholesterol (mmol/L) | 3.67 (3.15, 4.27) | 3.59 (3.03, 4.40) | 3.62 (3.05, 4.29) | 0.526 |
| Plasma:HDL-cholesterol ratio | 4.16 (3.40, 5.29) | 4.16 (3.52, 5.07) | 4.16 (3.48, 5.16) | 0.771 |
| Plasma triglycerides (mmol/L) | 1.54 (1.02, 2.21) | 1.75 (1.22, 2.37) | 1.69 (1.10, 2.31) | 0.119 |
| Fasting serum insulin (mIU/L) | 13.2 (9.0, 20.0) | 14.4 (10.3, 22.1) | 13.8 (9.6, 21.2) | 0.386 |
| Fasting plasma glucose (mmol/L) | 7.8 ± 2.3 | 8.2 ± 2.4 | 8.0 ± 2.4 | 0.136 |
| Glycosylated hemoglobin (%) | 7.1 ± 1.1 | 7.0 ± 1.1 | 7.1 ± 1.1 | 0.724 |
| Plasma trans fatty acids (mg/L) | 43 (28, 62) | 54 (38, 74) | 49 (35, 69) | 0.006 |
| Plasma SFAs (mg/L) | 957 (785, 1208) | 969 (834, 1208) | 965 (812, 1208) | 0.128 |
| Plasma cis-MUFAs (mg/L) | 807 (619, 1030) | 862 (701, 1090) | 847 (675, 1065) | 0.005 |
| Plasma PUFAs (mg/L) | 1543 (1311, 1702) | 1487 (1308, 1745) | 1503 (1308, 1732) | 0.666 |
| Plasma total fatty acids (mg/L) | 3316 (2790, 3958) | 3398 (2969, 4094) | 3359 (2900, 4031) | 0.107 |
| Daily activity (kcal) | 611 (407, 762) | 515 (398, 682) | 558 (404, 717) | 0.042 |
| Dietary variables | ||||
| Dietary trans fatty acids (g/d) | 4.5 (2.9, 7.0) | 4.9 (3.2, 7.6) | 4.7 (3.1, 7.4) | 0.124 |
| Dietary SFAs (g/d) | 24.1 (16.3, 38.3) | 25.8 (19.0, 41.6) | 25.6 (18.1, 41.0) | 0.169 |
| Dietary oleic acid (g/d) | 28.0 (19.4, 42.0) | 31.7 (22.5, 48.0) | 30.7 (21.4, 45.8) | 0.022 |
| Dietary PUFAs (g/d) | 13.9 (9.6, 19.0) | 15.4 (10.8, 21.7) | 15.0 (10.4, 21.1) | 0.081 |
| Dietary total fat (g/d) | 74.0 (52.5, 114.6) | 83.3 (58.9, 122.6) | 78.1 (55.9, 120.2) | 0.116 |
| Total energy intake (kcal/d) | 1666 (1220, 2247) | 1782 (1335, 2712) | 1738 (1289, 2506) | 0.126 |
| Dietary trans fatty acids (% of energy) | 2.4 (1.9, 2.9) | 2.4 (1.9, 3.1) | 2.4 (1.9, 3.0) | 0.447 |
P values for difference between clinical sites. Except as noted, frequencies were compared by chi-square test; normally distributed variables shown as means ± SDs were compared by t test. Variables shown as medians (IQR) could be normalized by log transformation, and log-transformed values were compared by t test.
Exceptions to these numbers are as follows: for whole-blood glycosylated hemoglobin, fasting plasma glucose, and plasma lipids and lipoproteins (Baltimore clinic: n = 116–118; Houston clinic: n = 164–165; total: n = 281–282); for serum insulin (Baltimore clinic: n = 120; Houston clinic: n = 181; total: n = 301); for dietary variables (Baltimore clinic: n = 95; Houston clinic: n = 178; total: n = 273); and for physical activity (Baltimore clinic: n = 101; Houston clinic: n = 156; total: n = 257).
Fisher's exact test.
Mean ± SD (all such values).
Median; IQR in parentheses (all such values).