In the paper titled “Association between anemia and cerebral venous thrombosis (CVT): a case-control study”, Jonathan Coutinho and colleagues set out to evaluate the association of CVT and anemia. They evaluated 156 cases at their institution between 2006 and 2004 and compared their characteristics to 2916 controls, which were taken from the Dutch MEGA study (Multiple Environmental and Genetic Assessment of risk factors for venous thrombosis) from 1999 to 2004.
Mean hemoglobin concentration was lower in cases than in controls (8.06 vs. 8.68 mmol/l, p<0.001). Anemia was present in 27.0 % (41/152) of the cases, significantly more frequently than in controls (6.5%, 189/2916; absolute difference 20.5%, 95% CI 14 – 28%). Patients with CVT more often had been diagnosed with cancer (9.2 vs. 3.7%) compared to controls (table 1). Oral contraceptive use (69.7% vs. 21.1%) and pregnancy/puerperium (5.3 vs. 1.4%) were more frequent in female cases. After adjustment for potential confounders, anemia was significantly associated with CVT (adjusted OR 4.4, 95% CI 2.8-6.9). Exclusion of patients with a recent infection, neurosurgical intervention, or inflammatory bowel disease, did not change the results (adjusted OR 3.9, 95% CI 2.4-6.4). When they excluded patients with a history of malignancy, the association between anemia and CVT remained significant (adjusted OR 3.6, 95% CI 2.2- 5.9). They also found that anemia is a stronger risk factor for CVT in men than in women.
This study sheds light on the possible association between CVT and anemia, which have been reported in prior case reports and small case series. However any causal correlations are difficult to extrapolate from this data. None the less this important association may be useful in monitoring patients at higher risk for CVT.