97 (95% CI 1.03 to 3.78)).34 Explanations for this discrepancy are unclear sellectchem but may include more extensive control for confounding factors in the present study. The observed excess mortality related

to amiodarone use should be interpreted within the context that only 7.7% of patients with AF are users of this drug. In this study cohort, prescription of amiodarone may have been reserved for special circumstances, such as for patients with impaired left ventricular function who poorly tolerate drugs with negative inotrope properties. Even though we adjusted for diagnosed heart failure, the mortality difference between amiodarone users and non-users could be related to differences in cardiac performance because the data set did not include quantitative measures of heart failure severity. A well-described side effect of amiodarone treatment is the development of pulmonary fibrosis,36 which may have been a factor that contributed to the excess mortality observed among amiodarone users. The finding of increased mortality in patients with AF using digoxin was alarming. Since digoxin was the single most used AF drug in our cohort, it seems unlikely that digoxin

users represent a selected sample of patients with particularly severe AF. The effect of cardiac-acting calcium-channel blockers on the prognosis of acute disease has not been investigated. We found that there was a slightly increased 30-day mortality in patients with AF using calcium-channel blockers, but there were no mortality differences 1 year after admission. We found that compared with non-users, patients with AF treated with vitamin K antagonists had a markedly reduced mortality

rate and risk of arterial thromboembolism. The role of preadmission treatment with vitamin K antagonists has not been investigated previously in patients with pneumonia. However, severe and uncomplicated infections induce increased activity of the coagulation system and the degree of coagulation abnormality at hospital admission is correlated with the outcome of community-acquired pneumonia.37 38 Thus, we speculate that the beneficial effect of vitamin K antagonist treatment may be related to protection from Dacomitinib hypercoagulation induced by systemic inflammation. This may also explain the finding of favourable prognosis with preadmission use of vitamin K antagonists in patients without AF. We did not find that mortality of aspirin users was reduced in patients with pneumonia with AF. Furthermore, aspirin use by patients with AF was associated with only a modest risk reduction from arterial thromboembolisms. Our findings agree with the findings of clinical studies that indicate that aspirin use in patients with AF has little benefit for prevention of stroke.39 Of note, we found preadmission use of aspirin to be associated with reduced mortality in patients without AF, which is in line with a previous study.