Westerlind H, et al. - Researchers assessed 8,109 subjects with incident rheumatoid arthritis (RA) between 1996 and 2016 and 11,562 of their full siblings to assess the risk of acute coronary syndrome (ACS) among full siblings of RA cases. Using Cox regression, they measured the HR of ACS among RA cases and their siblings vs the general population, overall and stratified by RA serostatus. They found higher risks in siblings of those with seropositive RA. They did not observe any significant increase in risk among siblings of subjects with seronegative RA.