Non-Traumatic Subdural Hematoma and Cancer: A Cohort Study

Søren Hauge Okholm,1 Dávid Nagy,1 Dóra Körmendiné Farkas,1 Cecilia Hvitfeldt Fuglsang,1 Frederikke Schønfeldt Troelsen,1 Victor W Henderson,1,2 Henrik Toft Sørensen1 1Department of Clinical Epidemiology, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark; 2Departments of Epidemiology & Population Health and of Neurology & Neurological Sciences, Stanford University, Stanford, CA, USACorrespondence: Henrik Toft Sørensen, Department of Clinical Epidemiology, Aarhus University Hospital and Aarhus University, Olof Palmes Allé 43-45, Aarhus N, 8200, Denmark, Tel +45 87 16 82 15, Email hts@clin.au.dkIntroduction: Cancer may increase the risk of bleeding. However, whether subdural hematoma is a marker of occult cancer remains unknown. We examined the association between non-traumatic subdural hematoma and cancer risk in a cohort study.Materials and Methods: Using Danish nationwide health registries, we identified 2713 patients with non-traumatic subdural hematoma and no previous cancer diagnosis, who were hospitalized between April 1, 1996 and December 31, 2019. We computed age-, sex-, and calendar year-standardized incidence ratios (SIRs) as the ratio of the observed to expected number of patients with cancer by using national incidence rates as reference as a measure of relative risk.Results: We identified 77 cancer cases within the first year of follow-up and 272 cancer cases thereafter. The one-year risk of cancer was 2.8% (95% confidence interval: 2.2– 3.5), and the one-year SIR was 1.7 (95% confidence interval: 1.3– 2.1). During the subsequent years, the SIR was 1.0 (95% confidence interval: 0.9– 1.1). The relative risk was elevated for some hematological and liver cancers.Conclusion: The risk of a new cancer diagnosis was clearly increased in patients with non-traumatic subdural hematoma compared with the general population during the first year of follow-up. However, the absolute risk was low, thus limiting the clinical relevance of pursuing early cancer detection in these patients.Keywords: cancer, cohort study, epidemiology, non-traumatic subdural hematoma, population-based