Table 1.
Demographic and clinical characteristics of the study population, N = 6,130
| Characteristics | Normal Platelet Count, >150×109/L (n = 1,750) | Mild Thrombocytopenia, 100–150×109/L (n = 2,726) | Moderate/Severe Thrombocytopenia, <100×109/L (n = 1,654) | P value |
|---|---|---|---|---|
| Demographics | ||||
| Age categories, years | < 0.0001 | |||
| <55 | 517 (29.5) | 496 (18.2) | 212 (12.8) | |
| 55–64 | 593 (33.9) | 862 (31.6) | 464 (28.1) | |
| 65–74 | 465 (26.6) | 922 (33.8) | 578 (35.0) | |
| 75–84 | 165 (9.4) | 410 (15.0) | 360 (21.8) | |
| >84 | 10 (0.6) | 36 (1.3) | 40 (2.4) | |
| Race | 0.0223 | |||
| White | 1280 (73.1) | 2111 (77.4) | 1258 (76.0) | |
| African American | 364 (20.8) | 469 (17.2) | 298 (18.0) | |
| Other | 106 (6.1) | 146 (5.4) | 98 (5.9) | |
| Female sex | 496 (28.3) | 670 (24.6) | 527 (31.9) | < 0.0001 |
|
| ||||
| Medical history* | ||||
| EuroSCORE-related variables | ||||
| Chronic obstructive pulmonary disease | 268 (15.3) | 424 (15.6) | 254 (15.4) | 0.9720 |
| Peripheral vascular disease | 268 (15.3) | 482 (17.7) | 319 (19.3) | 0.0086 |
| Cerebrovascular accident | 151 (8.6) | 261 (9.6) | 177 (10.7) | 0.1217 |
| Previous cardiac surgery | 14 (0.8) | 40 (1.5) | 38 (2.3) | 0.0016 |
| Serum creatinine > 2 mg/dL | 80 (4.6) | 163 (6.0) | 126 (7.6) | 0.0009 |
| Critical preoperative state | 23 (1.3) | 36 (1.3) | 39 (2.4) | 0.0158 |
| Unstable angina pectoris | 311 (17.8) | 487 (17.9) | 288 (17.4) | 0.978 |
| Left ventricular function | < 0.0001 | |||
| Normal | 915 (52.3) | 1,375 (50.4) | 711 (43.0) | |
| Moderate dysfunction | 693 (39.6) | 1,099 (40.3) | 675 (40.8) | |
| Severe dysfunction | 142 (8.1) | 252 (9.2) | 268 (16.2) | |
| Recent myocardial infarction | 588 (33.6) | 713 (26.2) | 464 (28.1) | < 0.0001 |
| 52 (3.0) | 82 (3.0) | 59 (3.6) | 0.5203 | |
| Pulmonary hypertension | 737 (42.1) | 983 (36.1) | 633 (38.3) | 0.0003 |
| Diabetes mellitus | ||||
|
| ||||
| Laboratory tests results | ||||
| Preoperative: | ||||
| Platelet count, 109/L | 266.0 [230.0, 315.0] | 208.0 [179.0, 243.0] | 176 [147.0, 212.0] | < 0.0001 |
| Creatinine, mg/dL | 1.0 [0.9, 1.2] | 1.1 [0.9, 1.3] | 1.1 [0.9, 1.4] | < 0.0001 |
| Hemoglobin, g/dL | 12.9 [11.6, 14.2] | 13.3 [11.9, 14.5] | 13.0 [11.6, 14.3] | < 0.0001 |
| Postoperative | ||||
| † Nadir platelet count, 109/L | 177.0 [161.0, 201.0] | 123.0 [111.0, 135.0] | 82.0 [69.0, 92.0] | < 0.0001 |
| Maximum creatinine, mg/dL | 1.2 [1.0, 1.5] | 1.2 [1.0, 1.6] | 1.4 [1.1, 1.9] | < 0.0001 |
| † Nadir hemoglobin, g/dL | 8.9 [8.1, 9.7] | 8.8 [8.1, 9.6] | 8.7 [8.0, 9.4] | < 0.0001 |
|
| ||||
| Preoperative medications** | ||||
| Acetylsalicylic acid | 1124 (64.9) | 1768 (64.9) | 1067 (64.5) | 0.9382 |
| Alpha-receptor blockers | 75 (4.3) | 142 (5.2) | 96 (5.8) | 0.1246 |
| Angiotensin converting enzyme inhibitors | 680 (39.0) | 1036 (38.6) | 616 (37.7) | 0.6275 |
| Angiotensin II receptor antagonist | 153 (8.8) | 230 (8.5) | 138 (8.4) | 0.9038 |
| Beta-receptor blockers | 1027 (59.3) | 1590 (58.9) | 971 (59.1) | 0.9274 |
| Calcium-channel blockers | 341 (19.7) | 499 (18.5) | 293 (17.9) | 0.3905 |
| Clopidogrel | 228 (13.2) | 332 (12.3) | 199 (12.2) | 0.6123 |
| Diuretics | 473 (27.3) | 663 (24.6) | 486 (29.7) | 0.0008 |
| Nitrates | 678 (39.2) | 997 (36.9) | 609 (37.3) | 0.2955 |
| Statins | 961 (55.5) | 1463 (54.2) | 873 (53.4) | 0.4518 |
| Warfarin | 32 (1.9) | 79 (2.9) | 71 (4.3) | 0.0001 |
|
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| Intraoperative characteristics | ||||
| Year of surgery | < 0.0001 | |||
| 2001 | 155 (8.9) | 349 (12.8) | 240 (15.0) | |
| 2002 | 159 (9.1) | 313 (11.5) | 210 (12.7) | |
| 2003 | 130 (7.4) | 251 (9.2) | 141 (8.5) | |
| 2004 | 135 (7.7) | 178 (6.5) | 99 (6.0) | |
| 2005 | 119 (6.8) | 166 (6.1) | 116 (7.0) | |
| 2006 | 115 (6.6) | 158 (5.8) | 118 (7.1) | |
| 2007 | 113 (6.4) | 162 (5.9) | 88 (5.3) | |
| 2008 | 99 (5.7) | 156 (5.7) | 91 (5.5) | |
| 2009 | 113 (6.5) | 177 (6.5) | 91 (5.5) | |
| 2010 | 123 (7.0) | 148 (5.4) | 93 (5.6) | |
| 2011 | 86 (4.9) | 136 (5.0) | 73 (4.4) | |
| 2012 | 85 (4.8) | 141 (5.2) | 63 (3.8) | |
| 2013 | 96 (5.5) | 142 (5.2 | 82 (5.0) | |
| 2014 | 133 (7.6) | 155 (5.7) | 84 (5.1) | |
| 2015 | 89 (5.1) | 94 (3.5) | 57 (3.5) | |
| Duration of cardiopulmonary bypass, minutes | 111.0 [91.0, 136.0] | 121.0 [98.0148.0] | 133.0 [106.0, 167.0] | < 0.0001 |
| Duration of aortic cross clamp, minutes | 64.0 [49.0, 83.0] | 70.0 [52.0, 88.0] | 75.0 [56.0, 95.0] | < 0.0001 |
| Intraoperative insertion of intra-aortic balloon pump | 88 (5.0) | 180 (6.6) | 248 (15.0) | < 0.0001 |
|
| ||||
| Intraoperative medications | ||||
| Aminocaproic acid | 1256 (71.8) | 1,959 (71.9) | 1,143 (69.1) | 0.1131 |
| Aprotinin | 182 (10.4) | 322 (11.8) | 250 (15.1) | 0.0001 |
| Epinephrine | 532 (30.4) | 907 (33.3) | 750 (45.3) | < 0.0001 |
| Norepinephrine | 68 (3.9) | 139 (5.1) | 152 (9.2) | < 0.0001 |
| Vasopressin | 459 (26.2) | 720 (26.4) | 458 (27.7) | 0.5647 |
| Nitroprusside | 484 (27.7) | 788 (28.9) | 490 (29.6) | 0.4335 |
| Nitroglycerin | 890 (50.9) | 1,546 (56.7) | 935 (56.5) | 0.0002 |
| Esmolol | 43 (2.5) | 63 (2.3) | 47 (2.8) | 0.5473 |
| Metoprolol | 1067 (61.0) | 1,698 (62.3) | 949 (57.4) | 0.0051 |
| Tranexamic acid | 251 (14.3) | 294 (10.8) | 176 (10.6) | 0.0004 |
|
| ||||
| Perioperative blood product use within 2 days | ||||
| Red blood cells, mL | 778 (44.5) | 1,567 (57.5) | 1,240 (75.0) | < 0.0001 |
| Fresh frozen plasma, mL | 193 (11.0) | 573 (21.0) | 576 (34.8) | < 0.0001 |
| Platelets, mL | 289 (16.5) | 755 (27.7) | 751 (45.4) | < 0.0001 |
| Cryoprecipitate, mL | 27 (1.5) | 100 (3.7) | 127 (7.7) | < 0.0001 |
Values are expressed as mean + standard deviation, median [interquartile range], or n (%).
*
The definitions of these risk factors were based on the definitions used by the European System for Cardiac Operative Risk Evaluation (EuroSCORE) scoring system.19
†
Postoperative nadir platelet counts and hemoglobin concentrations were defined as the lowest in-hospital values. In patients who experienced postoperative stroke, the lowest platelet value and hemoglobin value prior to stroke were used.
**
Due to missing data (1.03%), preoperative medication use was computed for n = 1,731 patients with normal platelets, for n = 2,701 patient with mild thrombocytopenia, and for n = 1,635 patients with moderate/severe thrombocytopenia.