Table 1.
Baseline Characteristics of the Study Participants and Reference Cohort.*
| Characteristic | Surgery Group (N = 2007) |
Control Group (N = 2040) |
Reference Cohort (N = 1135) |
|---|---|---|---|
| Age — yr | 47.2±5.9 | 48.7±6.3 | 49.5±7.0 |
| Male sex — no. (%) | 587 (29.2) | 593 (29.1) | 524 (46.2) |
| Body-mass index† | 42.4±4.5 | 40.1±4.7 | 25.2±3.8 |
| Waist:hip ratio | 0.992±0.078 | 0.978±0.074 | 0.881±0.082 |
| Cardiovascular disease before baseline — no. (%) | 46 (2.3) | 49 (2.4) | 22 (1.9) |
| Cancer before baseline — no. (%) | 25 (1.2) | 22 (1.1) | 24 (2.1) |
| Hypertension — no./total no. (%) | 1571/2004 (78.4) | 1301/2038 (63.8) | 312/1129 (27.6) |
| Glucose tolerance — no./total no. (%)‡ | |||
| Normal | 1355/2000 (67.8) | 1483/2036 (72.8) | 999/1132 (88.3) |
| Impaired | 301/2000 (15.0) | 290/2036 (14.2) | 95/1132 (8.4) |
| Type 2 diabetes | 344/2000 (17.2) | 263/2036 (12.9) | 38/1132 (3.4) |
| Insulin level — mU/liter | 21.5±13.7 | 18.0±11.4 | 8.6±5.1 |
| Total cholesterol level — mmol/liter | 5.9±1.1 | 5.6±1.1 | 5.5±1.0 |
| Daily smoking — no./total no. (%) | 518/2005 (25.8) | 422/2030 (20.8) | 235/1134 (20.7) |
| University education — no./total no. (%) | 257/2007 (12.8) | 431/2040 (21.1) | 375/1134 (33.1) |
| Married or living with a partner — no./total no. (%) | 1460/2002 (72.9) | 1527/2029 (75.3) | 911/1133 (80.4) |
| History of substance abuse — no. (%) | 58 (2.9) | 50 (2.5) | 10 (0.9) |
| Psychiatric care or medication before baseline — no. (%) | 355 (17.7) | 324 (15.9) | 83 (7.3) |
Plus-minus values are means ±SD. There were imbalances (P<0.05) between the surgery and control groups with respect to age, body-mass index, waist:hip ratio, hypertension, glucose tolerance, insulin level, total cholesterol level, smoking status, and university education, and between the reference cohort and the control group with respect to all variables except cardiovascular disease and smoking.
The body-mass index is the weight in kilograms divided by the square of the height in meters.
Glucose tolerance was classified as normal (fasting blood glucose level, <90 mg per deciliter [<5.0 mmol per liter]), impaired (≥90 to <110 mg per deciliter [≥5.0 to <6.0 mmol per liter]), or type 2 diabetes (≥110 mg per deciliter [≥6.1 mmol per liter]).