Background: Early cardiology involvement within 90 days of atrial fibrillation (AF) diagnosis is associated with greater likelihood of oral anticoagulant use and a reduced risk of stroke. Due to variation in cardiovascular care for patients with cancer, it is possible that a similar association does not exist for AF patients with cancer.
Methods: We examined the association of early cardiology involvement with oral anticoagulation use among non-valvular AF patients with history of cancer (past or active), using data from 388,045 patients (mean age=68±15 years; 59% male) from the MarketScan database (2009-2014). ICD-9 codes in any position were used to identify cancer diagnosis prior to AF diagnosis. Provider specialty and filled anticoagulant prescriptions 3 months prior to and 6 months after AF diagnosis were obtained. Poisson regression models were used to compute the probability of an oral anticoagulant prescription fill and Cox regression was used to estimate the risk of stroke and major bleeding.
Results: A total of 64,016 (17%) AF patients had a prior history of cancer. Cardiology involvement was less likely to occur among patients with history of cancer than those without (relative risk=0.92, 95% confidence interval (0.91, 0.93)). Similar differences were observed for cancers of the colon (0.90 (0.88, 0.92)), lung (0.76 (0.74, 0.78)), pancreas (0.74 (0.69, 0.80)), and hematologic system (0.88 (0.87, 0.90)), while no differences were observed for breast or prostate cancers. Patients with cancer were less likely to fill prescriptions for anticoagulants (0.89 (0.88, 0.90)) than those without cancer, and similar results were observed for cancers of the colon, lung, prostate, pancreas, and hematologic system. However, patients with cancer were more likely to fill prescriptions for anticoagulants (1.48 (1.45, 1.52)) if seen by a cardiology provider, regardless of cancer type. A reduced risk of stroke (hazard ratio=0.89 (0.81, 0.99)) was observed among all cancer patients who were seen by a cardiology provider than among those who were not, without an increased risk of bleeding (1.04 (0.95, 1.13)).
Conclusion: AF patients with cancer were less likely to see a cardiologist, and less likely to fill an anticoagulant prescription than AF patients without cancer. However, cardiology involvement was associated with increased anticoagulant prescription fills and reduced risk of stroke, suggesting a beneficial role for cardiology providers to improve outcomes in AF patients with history of cancer.