Table 2.
Univariate Analysis of Possible Risk Factors for POH After Elective Cardiac Surgery in the Training Set
| Characteristics |
Without POH n=2161 (%) |
With POH n=6799 (%) |
P value |
|---|---|---|---|
| Demographics | |||
| Men | 3719 (54.7) | 1103 (51.0) | 0.003 |
| Age, y | 51.81±13.13 | 50.58±13.08 | <0.001 |
| Body mass index, kg/m2 | 23.08±3.28 | 23.21±3.32 | 0.113 |
| Smoking history | 1660 (24.4) | 735 (34.0) | <0.001 |
| Drinking history | 1323 (19.5) | 489 (22.6) | 0.001 |
| Underlying conditions | |||
| Hypertension | 1501 (22.1) | 742 (34.3) | <0.001 |
| Diabetes | 483 (7.1) | 199 (9.2) | 0.001 |
| Chronic headache history | 600 (8.8) | 366 (16.9) | <0.001 |
| Chronic obstructive pulmonary disease | 708 (10.4) | 339 (15.7) | <0.001 |
| Cerebrovascular disease | 1206 (17.7) | 370 (17.1) | 0.512 |
| Peripheral vascular disease | 1513 (22.3) | 480 (22.2) | 0.968 |
| Renal insufficiency | 418 (6.1) | 234 (10.8) | <0.001 |
| Gastrointestinal tract disease | 592 (8.7) | 161 (7.5) | 0.067 |
| Atrial fibrillation | 1191 (17.5) | 527 (24.4) | <0.001 |
| Cardiac surgery history | 398 (5.9) | 228 (10.6) | <0.001 |
| General surgery history | 1928 (28.4) | 649 (30.0) | 0.134 |
| Pulmonary artery hypertension | 1946 (28.6) | 664 (30.7) | 0.061 |
| Pericardial effusion | 799 (11.8) | 347 (16.1) | <0.001 |
| NYHA class III or IV | 908 (13.4) | 601 (27.8) | <0.001 |
| LVEF, % | 63 (59–67) | 59 (54–63) | <0.001 |
| Laboratory values | |||
| White blood cell count, ×109/L | 5.64 (4.70–6.75) | 5.77 (4.78–6.85) | 0.009 |
| RBC count, ×1012/L | 4.31 (3.95–4.67) | 4.24 (3.88–4.62) | <0.001 |
| Hemoglobin, g/L | 130 (119–142) | 127 (116–139) | <0.001 |
| Red cell distribution width, % | 14.1 (11.6–15.7) | 14.3 (11.7–15.8) | 0.023 |
| Serum creatinine, μmol/L | 70.9 (60.7–83.3) | 71.3 (59.8–85.6) | 0.205 |
| Serum albumin, g/L | 40.7 (38.5–42.9) | 40.4 (38.0–42.7) | <0.001 |
| Serum globulin, g/L | 24.2 (21.6–27.0) | 24.4 (21.8–27.4) | 0.004 |
| Operative variables | |||
| Surgical types | <0.001 | ||
| Isolated valve surgery | 4358 (64.1) | 1240 (57.4) | |
| Isolated coronary artery bypass grafting | 612 (9.0) | 238 (11.0) | |
| Mixed valve and coronary surgery | 594 (8.7) | 398 (18.4) | |
| Other types | 1235 (18.2) | 285 (13.2) | |
| Cardiopulmonary bypass time, min | 94 (73–119) | 127 (104–156) | <0.001 |
| Aortic cross clamp time, min | 62 (44–82) | 85 (66–108) | <0.001 |
| Transfusion of RBCs, units | 1.0 (0–2.5) | 2.5 (1.0–4.5) | <0.001 |
LVEF indicates left ventricular ejection fraction; POH, postoperative headache; and RBC, red blood cell.