Alopecia areata does not increase the risk of venous thromboembolism: an All of Us case-control study

Alopecia areata (AA) is an autoimmune disease driven by cytokine dysregulation resulting in hair loss, and recent data suggests inflammation may be occurring systemically. This systemic increase in inflammatory cytokines may increase the incidence of thrombotic events, including deep vein thrombosis, stroke, myocardial infarction, and pulmonary embolism. As the use of JAK inhibitors for AA becomes more common, it is important to further investigate this potential relationship to prevent exacerbation of such events. The purpose of this case-control study was to determine if there is an increased association between thrombotic events and alopecia areata using the All of Us database. We matched 926 patients with AA 4:1 to controls without any alopecia, and we found that there was a statistically significant increase in the incidence of venous thromboembolism (VTE) in patients with AA (p = 0.009). Multivariable conditional logistic regression was then used to estimate the odds of AA in relation to VTE, controlling for common hypercoagulable factors (atrial fibrillation, estrogen replacement, obesity, malignancy, pregnancy, and smoking history). We found that after controlling for these risk factors, there was no significant difference in the incidence in VTE between those with and without AA (OR: 1.549, CR 95% (0.862, 2.783)). While recent reports have suggested alopecia areata to be significantly associated with venous thromboembolisms, we did not observe a significant association after controlling for hypercoagulable factors.