Dog ownership and cardiovascular risk factors: a nationwide prospective register-based cohort study.

OBJECTIVE: To study the association between dog ownership and cardiovascular risk factors. DESIGN: A nationwide register-based cohort study and a cross-sectional study in a subset. SETTING: A cohort of 2 026 865 participants was identified from the Register of the Total Population and linked to national registers for information on dog ownership, prescribed medication, hospital admissions, education level, income and country of birth. Participants were followed from 1 October, 2006, to the end of the study on 31 December, 2012, assessing medication for a cardiovascular risk factor, emigration and death. Cross-sectional associations were further assessed in 10 110 individuals from the TwinGene study with additional adjustment for professional level, employment status, Charlson comorbidity index, disability and tobacco use. PARTICIPANTS: All Swedish residents aged 45-80 years on 1 October, 2006. MAIN OUTCOME MEASURES: Initiation of medication for hypertension, dyslipidaemia and diabetes mellitus. RESULTS: After adjustment for confounders, the results indicated slightly higher likelihood of initiating antihypertensive (HR, 1.02; 95% CI, 1.01 to 1.03) and lipid-lowering treatment (HR, 1.02; 95% CI, 1.01 to 1.04) in dog owners than in non-owners, particularly among those aged 45-60 years and in those owning mixed breed or companion/toy breed dogs. No association of dog ownership with initiation of treatment for diabetes was found in the overall analysis (HR, 0.98; 95% CI, 0.95 to 1.01). Sensitivity analyses in the TwinGene cohort indicated confounding of the association between dog ownership and prevalent treatment for hypertension, dyslipidaemia and diabetes mellitus, respectively, from factors not available in the national cohort, such as employment status and non cardiovascularchronic disease status. CONCLUSIONS: In this large cohort study, dog ownership was associated with a minimally higher risk of initiation of treatment for hypertension and dyslipidaemia implying that the previously reported lower risk of cardiovascular mortality among dog owners in this cohort is not explained by reduced hypertension and dyslipidaemia. These observations may suffer from residual confounding despite access to multiple important covariates, and future studies may add valuable information.

Clinical depression, antidepressant use and risk of future cardiovascular disease.

Many studies have shown that depression contributes to a higher risk of developing cardiovascular disease (CVD). Use of antidepressants and its association with CVD development has also been investigated previously but the results have been conflicting. Further, depression and use of antidepressants have been more widely studied in relation to coronary heart disease rather than stroke. A population-based cohort study consisting of 36,654 Swedish elderly twins was conducted with a follow-up of maximum 4 years. Information on exposures, outcomes and covariates were collected from the Swedish national patient registers, the Swedish prescribed drug registry and the Swedish twin registry. Depression and antidepressant use were both associated with CVD development. The risk was most pronounced among depressed patients who did not use antidepressants (HR 1. 48, CI 1.10-2.00). When assessing the two main CVD outcomes coronary heart disease and ischemic stroke separately, the predominant association was found for ischemic stroke while it was absent for coronary heart disease. The association between depression and stroke also remained significant when restricting to depression diagnoses occurring at least 10 years before baseline. The study supports that depression is a possible risk factor for development of CVD. Moreover, the hazard rate for CVD outcomes was highest among depressed patients who had not used antidepressants. The association with clinical depression is more marked in relation to stroke and disappears in relation to development of coronary heart disease.