Differences in quality of care among patients hospitalized with atrial fibrillation as primary or secondary cause for admission

Objective. Several factors have been linked to the variation in the quality of care for patients with atrial fibrillation (AF). Whether hospitalization primarily for AF (primary diagnosis of AF) as opposed to another primary diagnosis but having concomitant AF (secondary diagnosis of AF) impacts quality of care for AF is not known. Accordingly, we sought to evaluate the differences in quality of care of Medicare patients admitted with primary diagnosis versus secondary diagnosis of AF. Design and setting. We studied a random sample of Medicare fee-for-service discharges from Michigan's acute care hospitals over a 1-year period with a primary or secondary diagnosis of AF (ICD-9-CM 427.31). Main outcome measure. Warfarin use at the time of discharge. Results. Of 5993 patients in the study, 772 had a primary diagnosis of AF and 5221 had a secondary diagnosis of AF. Patients with a secondary diagnosis of AF were older, more likely to be male, and less likely to be hypertensive. Patients with a secondary diagnosis of AF 'ideal' for anticoagulation (n = 1648) were less likely to receive warfarin compared with 'ideal' patients with primary diagnosis of AF (n = 363) (52.6% versus. 59.8%, P < 0.001). Adherence to test indicators was lower in patients with secondary diagnosis of AF. Conclusion. Secondary diagnosis of AF rather than AF as a primary diagnosis appears to account for most Medicare patients with AF admitted to hospitals. Whereas quality of care is lower in patients with secondary diagnosis of AF, opportunity for quality improvement exists for both groups of patients with AF.