Risk of Venous Thromboembolism in Patients With Keratinocyte Carcinoma.

Importance: Although malignancy is an established risk factor for venous thromboembolism (VTE), the risk of VTE specifically in patients with keratinocyte carcinoma (KC) has not been previously studied.

Objective: To determine the risk of VTE in patients with KC compared with patients not diagnosed with cancer and with patients diagnosed with common malignant neoplasms associated with VTE.

Design, Setting, and Participants: Population-based retrospective analysis of patient insurance claims made between January 1, 2007, and December 31, 2014, from the Truven MarketScan Commercial and Medicare Supplemental Databases. Patients treated across the United States were divided into 3 cohorts: patients with KC, patients with pancreatic cancer or acute myelogenous leukemia who are thus at high risk for VTE, and patients without a history of common malignant neoplasms. Patients were excluded from the KC cohort if they had a history of another type of cancer. Data were analyzed between April 1, 2017, and January 15, 2018.

Main Outcomes and Measures: Diagnosis of VTE within 1 year following the index date (for the KC and high-risk cohorts, the date of the initial diagnosis of cancer; for the control cohort, the date following 365 days of continuous insurance enrollment). Logistic regression was used to assess the risk of VTE in the KC cohort compared with the high-risk and control cohorts before and after matching across patient characteristics and known risk factors for VTE.

Results: Of 5 753 613 potentially eligible patients, the final sample consisted of 740 246 patients (12.8%) across 3 cohorts. Of the 740 246 study participants, 417 839 were in the KC cohort (223 986 [53.6%] men, mean [SD] age, 64.2 [13.6] years); 314 736 were in the control cohort (135 203 [43.0%] men, 42.9 [15.2] years); and 7671 were in the high-risk cohort (3502 [45.7%] men, 59.4 [14.4] years) The risk of VTE in the KC cohort was lower compared with the high-risk cohort in univariable analysis (odds ratio [OR], 0.22; 95% CI, 0.20-0.23; P < .001), multivariable analysis (OR, 0.29; 95% CI, 0.26-0.32; P < .001), and after matching across patient characteristics and known risk factors (OR, 0.52; 95% CI, 0.35-0.78; P = .001). The risk of VTE in the KC cohort was higher in the univariable analysis (OR, 2.31; 95% CI, 2.23-2.41; P < .001), lower in the multivariable analysis (OR, 0.85; 95% CI, 0.80-0.90; P < .001), and not different after matching of patient characteristics and risk factors (OR, 0.95; 95% CI, 0.89-1.01; P = .08) than that of the control cohort.

Conclusions and Relevance: The results of this study provided no evidence supporting the increased risk of VTE in the KC cohort compared with the control cohort. Given the inherent risks of chemoprophylaxis, the need for prophylactic anticoagulation in patients with KC who are scheduled for surgery should be carefully considered.

Level of Evidence: NA.