PURPOSE: JAK-inhibitors (JAK-i) might be associated with venous (VTE) and arterial thromboembolic events (ATE). To evaluate the association between JAK-i and the risk of VTE and ATE. METHODS: A self-controlled case series was performed using data from the nationwide French healthcare insurance system database SNDS. We included all patients treated with JAK-i (baricitinib or tofacitinib), and having presented at least one VTE or ATE between November 1, 2017 and June 30, 2019. Associations were estimated using the incident rate ratio (IRR). Two post-exposure periods (until day 30 and until day 60) were individualized. RESULTS: Among 5870 patients with JAK-i dispensing, 92 had an incident VTE or ATE within the study period. Their median age at JAK-i initiation was 65.7 years [IQR: 56.1-75.8] and 65.2% were female (n = 60). Before event incidence, 65.2% (n = 60) received baricitinib, 32.6% (n = 30) tofacitinib and 2.2% (n = 2) had both medications. Moreover, 41.3% (n = 38) presented a VTE and 58.7% (n = 54) an ATE. The median time-to-onset after JAK-i initiation was 4.6 months [IQR: 2.5-9.2] for VTE and 6.1 months [IQR: 3.0-8.5] for ATE. An IRR of 8.27 (95% CI 3.41-20.04) for VTE was detected during JAK-i treatment and remained increased over the 30-day period of post-exposure (6.52 [2.02-21.11]). An IRR of 9.27 (3.68-23.34) was also found for ATE, which remained increased over the 30-day period of post-exposure (10.12 [3.27-31.37]). No increased risk was detected during long-term post-exposure for either VTE or ATE. CONCLUSIONS: This study shows evidence of an increased risk of VTE and ATE associated with the use of baricitinib and tofacitinib.< Réduire