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Letters to the Editor
Table 1. Demographic and clinical characteristics of the study patients, separately in the ‘stockings’ and ‘non-stockings’ groups.
Characteristics
Age, years,
mean ± SD median (range)
Males, n(%)
Obesity, n(%) Unprovoked DVT, n(%) Previous VTE, n(%) Symptoms of PE, n(%) DVT location, n(%)
common femoral vein ± popliteal vein
popliteal vein only
Vein abnormalities, n(%)
RVT (alone or combined with PVR)
PVR (alone or combined with RVT) Recurrent DVT and/or PE, n(%)
overall
ipsilateral DVT
Deaths, n(%)
Duration of treatment, months
Non-ECS group (N=350)
62.4 ± 16.5 62 (15-91) 163 (46.6) 48 (13.7) 180 (51.4) 52 (14.9) 59 (16.9)
166 (47.4) 184 (52.6)
176 (50.3) 108 (30.9)
53 (15.1) 14 (4.0) 21 (6.0)
ECS group (N=511)
58.1 ± 18.3 65.5 (18-89) 252 (49.3) 56 (11.0) 258 (50.5) 51 (10.0) 67 (13.1)
261 (51.1) 250 (48.9)
248 (48.5) 132 (25.8)
74 (14.5) 35 (6.8) 36 (7.0)
P
0.001
-
0.429 0.223 0.787 0.030 0.127
0.293
-
0.613 0.106
0.788 0.098 0.545
0.207
-
0.670
-
mean±SD 5.1±4.0 5.4±4.1
median (range) 3 (1-24) 3 (3-24) Duration of follow-up, months
mean±SD 34.0±6.3 34.2±5.9 median (range) 36 (6-36) 36 (6-36)
ECS:elasticcompressionstockings;SD:standarddeviation; DVT:deepveinthrombosis;VTE:venousthromboembolism;PE:pulmonaryembolism;RVT:residualveinthrom- bosis; PVR: popliteal valve reflux; Numbers in parentheses indicate percentages unless otherwise specified.
with and without RVT and/or PVR was estimated using the proportional hazard Cox regression model. Interaction terms were defined between RVT and ECS, and between PVR and ECS. A minimal significant model was achieved by a likelihood ratio-guided forward step- wise variable selection method. In each of the four sub- groups of patients with or without RVT and/or PVR in the ‘stockings’ or ‘non stockings’ group, the cumulative incidence of PTS was estimated by the Kaplan-Meier method, tested by the log-rank test, and graphically rep- resented by product-limit survival estimates by the final minimal significant model.
Of the 861 patients, 511 (59.3%) belonged to the ‘stockings’ group, and the remaining 350 (40.7%) to the ‘non-stockings’ group. The two groups had substantially comparable demographic and clinical characteristics (Table 1). RVT and/or PVR was detected in 539 patients (62.6%). Of these, RVT alone was found in 299 (55.5%), PVR alone in 115 (21.3%) patients, and the combination of RVT with PVR in 125 (23.2%).
PTS developed in 249 of the 539 patients (46.2%; severe in 35, 6.5%) with RVT and/or PVR, and in 90 of the 322 (28.0%; severe in 11, 3.4%) without RVT and/or PVR (HR=2.18; 95% confidence interval [95% CI], 1.73- 2.74). PTS developed in 162 of the 511 patients (31.7%; severe in 19, 3.7%) in the ‘stockings’ group, and in 177 of the 350 (50.6%; severe in 25, 7.1%) in the ‘non-stock- ings’ group (HR=0.64; 95% CI: 0.51-0.79; P<0.001).
In patients with RVT and/or PVR, PTS developed in 114 of the 328 (34.8%) in the ‘stockings’ group (severe in
14, 4.3%), and in 135 of the 211 (64.0%) in the ‘non- stockings’ group (severe in 19, 9.0%), for hazard ratios of all and severe PTS of 0.52 (95% CI: 0.41-0.66; P<0.001) and 0.41 (95% CI: 0.21-0.83; P=0.013), respectively. In patients without RVT and/or PVR, PTS developed in 48 of the 183 (26.2%) patients in the ‘stockings’ group (severe in 5, 2.7%), and 42 of the 139 (30.2%) patients in the ‘non-stockings’ group (severe in 6, 4.3%), for hazard ratios of all and severe PTS of 0.95 (95% CI: 0.62-1.44; P=0.80) and 0.59 (95% CI: 0.18-1.95; P=0.59), respective- ly (Table 2). In patients with RVT and/or PVR, the 36- month PTS-free survival figures were 35.2% (95% CI: 28.7-41.7) in the ‘non-stockings’ group, and 64.0% (95% CI: 58.7-69.3) in the ‘stockings’ group (P<0.001). In patients without RVT and/or PVR, the respective figures were 69.3% (95% CI: 61.5-77.1) and 73.5% (95% CI: 67.0-78.0), respectively (P=0.43) (Figure 1).
Of utmost importance, while the interaction term for the use of ECS and presence of RVT was highly signifi- cant (P=0.037), the term for the use of ECS and presence of PVR was not (P=0.46).
Our study strongly suggests that in patients with prox- imal DVT, adequate use of ECS provides a clinically important reduction in any and severe PTS in patients with ultrasound evidence of RVT (with or without PVR) at 3 months, whereas in patients without RVT such an effect is absent. In a clinical context dominated by per- sistent uncertainty on the necessity for compression ther- apy to prevent PTS, our study has the potential to revive a stalled discussion.
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haematologica | 2022; 107(1)