Background: Guidelines suggest the use of the Khorana score to select patients with solid cancer receiving chemotherapy for thromboprophylaxis to prevent venous thromboembolism (VTE), but its performance in different types of cancers remains uncertain.
Methods: The present analysis includes individual patient data from seven randomized controlled trials that had compared prophylactic (ultra)-low-molecular-weight heparin (LMWH) with placebo or observation in patients with solid cancer. The analysis addresses the performance of the continuous and dichotomized Khorana score in predicting the 6-month risk of VTE in the trial control groups, overall and in types of cancer studies, as well as the efficacy and safety of LMWH among patients with a high-risk Khorana score. Random effects meta-analysis provided the basis for summary estimates.
Findings: In the 3,403 patients from the control groups included in the analyses, the mean age was 61 years, 59% were male, and 58% had lung cancer. During 6-months of follow-up, 188 patients (5.5%) developed VTE. Overall, the 6-month VTE incidence was 9.8% among high-risk Khorana score patients and 6.4% among low-to-intermediate risk patients (OR 1.6; 95%-CI 1.1-2.2). The dichotomous Khorana score performed differently in lung cancer patients (OR 1.1; 95%-CI, 0.72-1.7) than in those with other types of cancer (OR 4.4; 95%-CI, 2.7-7.3; P interaction=0.002). Among high-risk patients, LMWH decreased the risk of VTE by 64% compared to placebo or observation (OR 0.36; 95%-CI, 0.22-0.58). In the group of patients with types of cancer other than lung cancer and a high-risk Khorana score (N=619), the 6-month VTE incidence was 3.3% (95% CI, 1.4 to 7.7) among LMWH recipients and 13% (95% CI, 6.8 to 24) among those not receiving LMWH (OR 0.23, 95% CI, 0.11 to 0.46; P <0.001). There was no difference in major bleeding (OR 1.2, 95% CI, 0.56 to 2.5).
Interpretation: The Khorana score performs poorly in differentiating between those at high and low risk of VTE in patients with lung cancer, but is associated with a 4-fold increased risk of VTE in those with other types of cancer. Thromboprophylaxis is effective and safe in patients with a high-risk Khorana score.
Funding: Canadian Institutes of Health Research knowledge synthesis grant, KRS 126594
Registration: International Prospective Register for Systematic Reviews (PROSPERO), CRD42013003526.
Van Es: Pfizer: Employment, Other: Comment: Dr. van Es reports personal fees from Pfizer as a member of their advisory board. These fees are unrelated to this project.. Crowther: Alexion: Speakers Bureau; Bayer: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Boehringer Ingelheim: Speakers Bureau; Leo Pharma: Research Funding; Pfizer: Honoraria; Portola: Consultancy; Shinogi: Consultancy. Macbeth: Cancer Research UK: Research Funding; Pfizer: Other: Provision of Dalteparin for FRAGMATIC trial. Griffiths: Pfizer: Consultancy, Other: Comment: I run an academic clinical trials unit, have received educational/investigator intiated research grants from companies that make these heparin agents. As consultant > 3 years ago, advised Pfizer on clinical trial designs unrelated to this study., Research Funding. Streiff: Roche: Research Funding; Portola: Research Funding; Janssen Scientific Affairs, LLC: Consultancy, Research Funding; CSL Behring: Consultancy, Research Funding. Ageno: Daiichi Sankyo: Consultancy, Honoraria; Bayer AG: Consultancy, Honoraria, Research Funding; BMS-Pfizer: Consultancy, Honoraria; Boehringer Ingelheim: Consultancy, Honoraria. Bozas: PharmaMar: Honoraria. Maraveyas: Bayer: Other: Personal fees and conference attendance; Bristol-Myers Squibb: Other: Grants and personal fees; Leo Pharma: Other: Grants, personal fees and conference attendance; Pfizer: Other: Personal fees. Loprinzi: Bristol Myers: Other: Grant - unrelated to this project; Janssen: Other: Grant - unrelated to this project. McBane: Bristol Myers Squibb: Other: Research grant for cancer associated VTE. Schünemann: Canadian Institutes of Health Research: Research Funding.
Asterisk with author names denotes non-ASH members.