Observational cohort study of the safety of digoxin use in women with heart failure

• Published in: BMJ open 2012-01, Vol.2 (2), p.e000888-e000888
• Main Authors: Flory, James H, Ky, Bonnie, Haynes, Kevin, M Brunelli, Steve, Munson, Jeffrey, Rowan, Christopher, Strom, Brian L, Hennessy, Sean
• Format: Article
• Language: English
• Subjects: Bias; Cardiovascular Medicine; Drug dosages; Heart failure; Hypotheses; Mortality; Population; Sexes; Studies; Women
• ISSN: 2044-6055; 2044-6055
• DOI: 10.1136/bmjopen-2012-000888

ObjectivesThis study aims to assess whether digoxin has a different effect on mortality risk for women than it does for men in patients with heart failure (HF).DesignThis study uses the UK-based The Health Information Network population database in a cohort study of the impact of digoxin exposure on mortality for men and women who carry the diagnosis of HF. Digoxin exposure was assessed based on prescribing data. Multivariable Cox proportional hazards models were used to assess whether there was an interaction between sex and digoxin affecting mortality hazard.SettingThe setting was primary care outpatient practices.ParticipantsThe study cohort consisted of 17 707 men and 19 227 women with the diagnosis of HF who contributed only time without digoxin exposure and 9487 men and 10 808 women with the diagnosis of HF who contributed time with digoxin exposure.Main outcome measuresThe main outcome measure was all-cause mortality.ResultsThe primary outcome of this study was the absence of a large interaction between digoxin use and sex affecting mortality. For men, digoxin use was associated with a HR for mortality of 1.00, while for women, the HR was also 1.00 (p value for interaction 0.65). The results of sensitivity analyses were consistent with those of the primary analysis.ConclusionObservational data do not support the concern that there is a substantial increased risk of mortality due to the use of digoxin in women. This finding is consistent with previous observational studies but discordant with results from a post hoc analysis of a randomised controlled trial of digoxin versus placebo.