A new study finds a lower incidence of AF in non-White races even though these groups have a higher risk of comorbidites that predispose to AF.
Over the past decade, racial differences in risk of developing cardiovascular disease and in some cases, differences in treatment efficacy, have continued to emerge and also to be better understood. In particular, racial differences in atrial fibrillation (AF) have been noted in multiple population-based observational studies that have demonstrated an increased incidence of AF in whites. It remains unclear whether white race confers additional AF risk or whether black race affords protection.
A study recently published in Circulation using data from the Healthcare Cost and Utilization Project studied almost 14 million participants seeking care in California between 2005 and 2009. The investigators used Cox proportional hazards models to elucidate the race-incident AF association during this period, in which there were 375,318 new diagnoses of AF. In a fully adjusted model, which controlled for demographic and known AF risk factors, there was significant heterogeneity in hazard for developing AF by race. Using whites as the comparator group, all other races demonstrated a lower adjusted hazard for developing AF (blacks HR = 0.84; Hispanics HR = 0.78; Asians HR = 0.78). These racial differences in rates of incident AF were higher in subjects with fewer cardiovascular comorbidities and were reduced with development of multiple cardiovascular comorbidities. Hispanics and Asians also had a lower adjusted risk of incident atrial flutter compared with whites, but the risk of developing flutter was significantly higher among blacks.
For reasons that are not completely understood, non-white races tended to have lower incident AF despite having a higher risk of comorbidities that increase risk for developing AF (such as an increased incidence of hypertension in blacks). These differences do not appear attributable to systematic bias or ascertainment bias, since the authors were able to prove no differences among races in rates of influenza or ventricular tachycardia. However, this was a database of inpatients only and it is possible that in a database that included outpatient visits, access to care for minorities may impact these results.
Regardless, it appears that there may be an independent relationship between white race and incident AF, especially in those with limited cardiovascular comorbidities. It is unclear whether this relationship is causal or whether race is just a marker for other underlying differences. For primary care providers, then, it is reasonable to consider white race as when assessing an individual’s risk for developing AF.
Dewland TA, Olgin JE, Vittinghoff E, Marcus GM. Incident atrial fibrillation among Asians, Hispanics, Blacks, and Whites. Circulation. 2013;128:2470-2477. (ABSTRACT)