The relation between age, sex, comorbidity, and pharmacotherapy and the risk of syncope: a Danish nationwide study

Aims Syncope is a common cause for hospitalization and may be related to comorbidity and concurrent medication. The objective of this study was to determine the incidence, comorbidity, and pharmacotherapy in a nationwide cohort of patients hospitalized with syncope. Methods and results An observational study including patients with the diagnosis of syncope identified from the Danish National Patient Register in the period 1997-2009. All patients were matched on sex and age with five controls from the Danish population. We estimated the incidence of syncope and the association with comorbidities and pharmacotherapy by conditional logistic regression analyses. We identified 127 508 patients with a first-time diagnosis of syncope [median age 65 years (interquartile range 49-81), 52.6% female]. The age distribution of the patients showed three peaks around 20, 60, and 80 years of age with the third peak occurring 5-7 years earlier in males. Cardiovascular disease and cardiovascular drug therapy was present in 28 and 48% of the patients, respectively. We found significant association between cardiovascular disease and the risk of admission for syncope increasing with younger age; age 0-29 years [odds ratio (OR) = 5.8, confidence interval (Cl): 5.2-6.4), age 30-49 (OR = 4.4, Cl: 4.2-4.6), age 50-79 (OR = 2.9, Cl: 2.8-3.0), and age above 80 (OR = 2.0, Cl: 1.9-2.0). Cardiovascular pharmacotherapy associated with age and risk of syncope was similar. Conclusion In a nationwide cohort of patients hospitalized for first syncope we found significant association between cardiovascular comorbidity and pharmacotherapy and the risk of syncope. The occurrence of syncope displayed an age distribution with important gender-specific differences and higher incidence rates than previously reported.