Table 5. Validation of risk factors adopted by Caprini RAM in the study population, with adjusted OR of VTE.
| Risk factor in Caprini RAM | Relative | Cases | Controls | Crude | Adjusted ORa | Adjusteda |
|---|---|---|---|---|---|---|
| Risk Score | (n = 902) | (n = 902) | P value | (95% CI) | P value | |
| Age, 41–60 | 1 | 285 (31.6) | 315 (34.9) | 0.134 | - | - |
| Age, 61–74 | 2 | 276 (30.6) | 285 (31.6) | 0.647 | - | - |
| Age, 75+ | 3 | 210 (23.3) | 142 (15.7) | < 0.001 | 1.20 (0.90–1.60) | 0.226 |
| Acute myocardial infarction | 1 | 8 (0.9) | 6 (0.7) | 0.592 | - | - |
| Heart failure | 1 | 60 (6.7) | 22 (2.4) | < 0.001 | 2.07 (1.14–3.76) | 0.017 |
| Varicose veins | 1 | 33 (3.7) | 10 (1.1) | < 0.001 | 1.97 (0.84–4.63) | 0.122 |
| Obesity (BMI > 25)b | 1 | 152 (26.1) | 83 (18.5) | 0.004 | 2.00 (1.37–2.91) | < 0.001 |
| Inflammatory bowel disease | 1 | 3 (0.3) | 5 (0.6) | 0.723 | - | - |
| Sepsis (< 1 mo) | 1 | 16 (1.8) | 13 (1.4) | 0.574 | - | - |
| COPD or abnormal pulmonary function | 1 | 138 (15.3) | 135 (15.0) | 0.844 | - | - |
| Severe lung disease, including pneumonia (< 1 mo) | 1 | 456 (50.6) | 325 (36.0) | < 0.001 | 2.10 (1.67–2.64) | < 0.001 |
| Oral contraceptives or hormone replacement therapy | 1 | 12 (1.3) | 20 (2.2) | 0.154 | - | - |
| Pregnancy or postpartum (< 1 mo) | 1 | 37 (4.1) | 1 (0.1) | < 0.001 | 40.78 (5.36–310.45) | < 0.001 |
| History of unexpected stillborn infant, recurrent spontaneous abortion (≥ 3), premature birth with toxemia or growth-restricted infant | 1 | 1 (0.1) | 2 (0.2) | 0.625 | - | - |
| Medical patient currently at bed rest | 1 | 96 (10.6) | 78 (8.6) | 0.151 | - | - |
| Minor surgery planned | 1 | 22(2.4) | 36(4.0) | 0.061 | - | - |
| History of prior major surgery(< 1 mo) | 1 | 37 (4.1) | 4 (0.4) | < 0.001 | 5.21 (1.61–16.86) | 0.006 |
| Swollen legs (current) | 1 | 321 (35.6) | 106 (11.8) | < 0.001 | 3.95 (3.00–5.21) | < 0.001 |
| Central venous access | 2 | 40 (4.4) | 32 (3.5) | 0.336 | - | - |
| Arthroscopic surgery | 2 | 0 (0.0) | 0 (0.0) | - | - | - |
| Major surgery (> 45 min) | 2 | 0 (0.0) | 0 (0.0) | - | - | - |
| Malignancy (present or previous) | 2 | 168 (18.6) | 192 (21.3) | 0.157 | - | - |
| Laparoscopic procedure > 45 min | 2 | 0 (0.0) | 0 (0.0) | - | - | - |
| Patient confined to bed (> 72 h) | 2 | 286 (31.7) | 44 (4.9) | < 0.001 | 9.20 (6.40–13.22) | < 0.001 |
| Immobilizing plaster cast (< 1 mo) | 2 | 4 (0.4) | 0 (0.0) | 0.133 | - | - |
| History of DVT/PE | 3 | 146 (16.2) | 4 (0.4) | < 0.001 | 38.75 (13.79–108.86) | < 0.001 |
| Positive Factor V Leiden; positive prothrombin G20210A; elevated serum homocysteinec | 3 | - | - | - | - | - |
| Positive Lupus anticoagulantc | 3 | - | - | - | - | - |
| Heparin-induced thrombocytopenia (HIT) | 3 | 4 (0.4) | 0 (0.0) | 0.133 | - | - |
| Family history of VTE | 3 | 7 (0.8) | 1 (0.1) | 0.068 | - | - |
| Elevated anticardiolipin antibodies | 3 | 18 (2.0) | 1 (0.1) | < 0.001 | 19.80 (2.45–160.27) | 0.005 |
| Stroke (< 1 mo) | 5 | 48 (5.3) | 5 (0.6) | < 0.001 | 8.71 (3.20–23.71) | < 0.001 |
| Multiple trauma (< 1 mo) | 5 | 7 (0.8) | 0 (0.0) | 0.023 | - | - |
| Elective major lower extremity arthroplasty | 5 | 1 (0.1) | 0 (0.0) | 0.317 | - | - |
| Hip, pelvis, or leg fracture (< 1 mo) | 5 | 14 (1.6) | 3 (0.3) | 0.007 | 4.42 (1.07–18.25) | 0.40 |
| Acute spinal cord injury (paralysis) (< 1 mo) | 5 | 6 (0.7) | 1 (0.1) | 0.130 | - | - |
| VTE prophylaxis | - | 37 (4.1) | 55 (6.1) | 0.054 | 0.49 (0.28–0.85) | 0.012 |
RAM = risk assessment model, OR = odds ratio, VTE = venous thromboembolism, CI = confidence interval, BMI = body mass index, mo = month
a
Variables that had a P-value < 0.05 in univariable crude analysis were selected for inclusion in the final multivariable model and VTE prophylaxis was also included.
b
Available in 583 cases, 449 controls.
c
These risk factors cannot be tested in the hospital.