Page 280 - Haematologica May 2020

A. Delluc et al.
the high-risk category with a pooled 6-month recurrence rate of VTE of 18.6% (95%CI: 13.9-23.9) (I2=64%, P=0.04) (Figure 2A). Of the remaining 795 patients (classified in the low-risk category), the pooled 6-month rate of recur- rent VTE was 7.4% (95%CI: 3.4-12.5) (I2=81%, P<0.01) (Figure 2B). The estimated pooled sensitivity, specificity, and Area Under the Receiver Operating Characteristic curve (AUROC) of the original score to identify high-risk patients were 0.7 (95%CI: 0.6-0.8), 0.5 (95%CI: 0.5-0.6), and 0.7 (0.6-0.8), respectively.
The modified score was derived in one and validated in four studies.9,13,16-18 The pooled 6-month rate of recurrent VTE in the 13,419 studied patients was 7.85% (95%CI: 4.79-11.57) (I2=95%, P<0.01). The modified score classi- fied 5,307 (39.5%) patients in the high-risk category, in which the pooled 6-month rate of recurrent VTE was 10.2% (95%CI: 6.4-14.6) (I2=89%, P<0.01) (Figure 3A). A total of 2,653 patients (19.8%) were classified in the low- risk category with a pooled 6-month rate of recurrent VTE of 2.2% (95%CI: 1.6-2.9) (I2=0%, P=0.51) (Figure 3B). For the remaining 5,459 patients in the intermediate-risk cate- gory, the pooled 6-month rate of recurrent VTE was 7.1% (3.8-11.3) (I2=90%, P<0.01) (Figure 3C).
The estimated pooled sensitivity, specificity, and AUROC of the modified score to identify high-risk patients were 0.5 (95%CI: 0.5-0.6), 0.6 (95%CI: 0.5-0.7), and 0.5 (95%CI: 0.5-0.6), respectively. For the identifica- tion of low-risk patients these characteristics were 0.9 (95%CI: 0.8-1.0), 0.2 (95%CI: 0.1-0.2), and 0.5 (95%CI: 0.5-0.7), respectively.
Pooled incidences of recurrent VTE for each point cate-
gory using the original and the modified Ottawa scores are reported in Online Supplementary Appendix 3. The rates of recurrent VTE ranged from 0 to 37.1% (95%CI: 12.7- 64.7) with a dose-effect association in studies applying the original score and ranged from 0 to 9.1% (95%CI: 0.2- 24.7) in studies applying the modified score with a step- wise association.
Discussion
This systematic review and meta-analysis of nine studies involving a total of 14,963 patients with cancer-associated VTE, confirms that the Ottawa score is an accurate tool to stratify the risk for recurrent VTE within the first six months of anticoagulation. The original Ottawa score can reliably identify patients with cancer-associated VTE at high risk of recurrent events, whereas the modified score is best suitable for identifying cancer patients with low risk of VTE recurrence. The original score classified 49.3% of the patients into the high-risk group with a sensitivity of 71% and the modified score classified 19.8% of the patients into the low-risk group with a sensitivity of 92%.
The Ottawa scores (original and modified) are the only tools available to stratify the risk for recurrence of cancer- associated VTE. The scores can help identify patients with a rate of recurrent VTE >10%. This has been suggested as clinically relevant and considered as a “high-risk” category.20 The Ottawa scores have better accuracy than the reported sensitivity, specificity or AUROC values, which were calculated based on crude rates of recurrent
AB
C
Figure 3. Pooled recurrence rates of venous thromboembolism for the modified Ottawa score. (A) Pooled recurrence rates of venous throm- boembolism for the modified Ottawa score in high-risk patients (B) Pooled recurrence rates of venous thromboembolism for the modified Ottawa score in intermediate-risk patients. (C) Pooled recurrence rates of venous thromboembolism for the modified Ottawa score in low-risk patients.
1440
haematologica | 2020; 105(5)