Westerlind H, et al. – Researchers examined the possible mutual susceptibility between rheumatoid arthritis (RA) and acute coronary syndrome (ACS) via estimation of the risk of ACS among full siblings of patients with RA. The study sample consisted of 8,109 patients with incident RA and 11,562 full siblings of these patients. Compared with the general population, the HR of ACS in RA was 1.46 and 1.22 among their siblings. The investigators found that the elevated risks appeared to be confined to seropositive RA. Among siblings of patients with seronegative RA, no significant risk increase was observed. Overall, siblings of patients with RA were found to be at higher risk of ACS, indicating shared susceptibility between RA and ACS, and signifying the necessity for additional cardio-preventive measures in patients with RA and their siblings.