Introduction
Methods
D-dimer interpretation strategy definitions
Age-adjusted strategy
Clinical probability-adjusted strategy
Outcome measures
Statistical analysis
Results
Parameter | No. (%) of patients | ||
---|---|---|---|
Low clinical probabilitya (N=163) | Intermediate clinical probabilityb (N=205) | Total (N=368) | |
Age ≥75 years | 63 (38.7) | 69 (33.7) | 132 (35.9) |
Sex | |||
Male | 124 (76.1) | 158 (77.1) | 282 (76.6) |
Female | 39 (23.9) | 47 (22.9) | 86 (23.4) |
Current smoker | 46 (28.2) | 72 (35.1) | 118 (32.1) |
Pack-years of smoking, mean (SD), no. | 58.2 (29.2) | 59.5 (25.8) | 59.0 (27.1) |
COPD exacerbations in the past 12 months, mean (SD), no. | 1.1 (1.6) | 1.5 (1.9) | 1.3 (1.8) |
Very severe COPD: <30% of the predicted normal FEV1 | 18 (11.0) | 37 (18.0) | 55 (14.9) |
Severe COPD: 30 to <50% of the predicted normal FEV1 | 70 (42.9) | 99 (48.3) | 169 (45.9) |
Moderate COPD: 50 to <80% of the predicted normal FEV1 | 56 (34.4) | 57 (27.8) | 113 (30.7) |
Mild COPD: ≥80% of the predicted normal FEV1 | 19 (11.7) | 12 (5.9) | 31 (8.4) |
Risk factors for VTE | |||
Immobilizationc | 1 (0.6) | 65 (31.7) | 66 (17.9) |
Cancerd | 6 (3.7) | 6 (2.9) | 12 (3.3) |
History of VTE | 0 (0) | 9 (4.4) | 9 (1.3) |
Surgerye | 0 (0) | 1 (0.5) | 1 (0.3) |
Obstructive sleep apnea | 36 (22.1) | 20 (9.8) | 56 (15.2) |
Congestive heart failure | 25 (15.3) | 23 (11.2) | 48 (13.0) |
Hormone therapy | 3 (1.8) | 2 (1.0) | 5 (1.4) |
Clinical symptoms and signs at presentation | |||
Dyspnea | 163 (100) | 203 (99.0) | 366 (99.5) |
Heart rate >100/min | 0 (0) | 127 (62.0) | 127 (34.5) |
Systolic blood pressure <100 mm Hg | 3 (1.8) | 8 (3.9) | 11 (16.2) |
Spo2 <90% (N=365) | 62 (38.3) | 83 (40.9) | 145 (39.7) |
Temperature ≥38°C | 0 (0) | 1 (0.5) | 1 (0.3) |
Increased sputum volume | 59 (36.2) | 69 (33.7) | 128 (34.8) |
Purulent sputum | 11 (6.7) | 13 (6.3) | 24 (6.5) |
Hemoptysis | 2 (1.2) | 1 (0.5) | 3 (0.8) |
Signs of DVT | 0 (0) | 0 (0) | 0 (0) |
Admission blood tests | |||
Creatinine >1.5 mg/dL | 4 (2.5) | 2 (1.0) | 6 (1.6) |
Hemoglobin, mean (SD), g/dL | 14.4 (1.9) | 14.1 (2.2) | 14.3 (2.1) |
Treatment for exacerbation | |||
Short-acting inhaled beta2-agonists | 159 (97.5) | 203 (99.0) | 362 (98.4) |
Short-acting inhaled anticholinergics | 163 (100) | 205 (100) | 368 (100) |
Systemic corticosteroids | 135 (82.8) | 165 (80.5) | 300 (81.5) |
Antibiotics | 113 (69.3) | 134 (65.4) | 247 (67.1) |
Pharmacological thromboprophylaxis (LMWH) | 163 (100) | 205 (100) | 368 (100) |
Comparison of the strategies
Parameter | Conventional strategy | Age-adjusted strategy | Wells-adjusted strategy | YEARS-adjusted strategy |
---|---|---|---|---|
Negative results | ||||
n/N | 182/368 | 233/368 | 237/368 | 368 |
% (95% CI) | 49.5 (44.2-54.7) | 63.3 (58.2-68.3) | 64.4 (59.3-69.3) | 71.5 (66.6-76.0) |
Sensitivity | ||||
n/N | 16/17 | 13/17 | 11/17 | 10/17 |
% (95% CI) | 94.1 (71.3-99.9) | 76.5 (50.1-93.2) | 64.7 (38.3-85.8) | 58.8 (32.9-81.6) |
Specificity | ||||
n/N | 181/351 | 229/351 | 231/351 | 256/351 |
% (95% CI) | 51.6 (46.2-56.9) | 65.2 (60.0-70.2) | 65.8 (60.6-70.8) | 72.9 (68.0-77.5) |
Negative predictive value | ||||
n/N | 181/182 | 229/233 | 231/237 | 256/263 |
% (95% CI) | 99.5 (97.0-100) | 98.3 (95.7-99.5) | 97.5 (94.6-99.1) | 97.3 (94.6-98.9) |
Negative likelihood ratio | 0.11 | 0.36 | 0.54 | 0.56 |
% (95% CI) | 1.66-2.29 | 0.15-0.85 | 0.28-1.03 | 0.32-1.00 |
Positive likelihood ratio | 1.95 | 2.20 | 1.89 | 2.17 |
% (95% CI) | 0.02-0.76 | 1.63-2.97 | 1.29-2.77 | 1.41-3.35 |
Age-adjusted strategy | ||||
D-dimer negative | D-dimer positive | Total | ||
Conventional strategy | D-dimer negative | 182 1 PE (0.5%) | 0 | 182 |
D-dimer positive | 51 3 PE (5.9%) | 135 13 PE (9.6%) | 186 | |
Total | 233 | 135 | 368 | |
Wells-adjusted strategy | ||||
D-dimer negative | D-dimer positive | Total | ||
Conventional strategy | D-dimer negative | 182 1 PE (0.5%) | 0 | 182 |
D-dimer positive | 55 5 PE (9.1%) | 131 11 PE (8.4%) | 186 | |
Total | 237 | 131 | 368 | |
YEARS-adjusted strategy | ||||
D-dimer negative | D-dimer positive | Total | ||
Conventional strategy | D-dimer negative | 182 1 PE (0.5%) | 0 | 182 |
D-dimer positive | 81 6 PE (7.4%) | 105 10 PE (9.5%) | 186 | |
Total | 263 | 105 | 368 |