Design: Systematic review and meta-analysis of randomised trials
Population: 139 trials, 292,027 patients with heart failure (28% women)
Primary outcome: Sex difference in treatment effect on the primary endpoint
Effect: Δ ln(relative effect) 0.00 (95% CI −0.04 to 0.03); I² 4%

This meta-analysis pooled 139 randomised trials of heart failure drugs with clinical event outcomes, covering 292,027 patients, of whom only 28% were women. Of these, 78 trials reported results by sex.

Treatment effects were essentially identical in women and men (difference in log relative effect 0.00, 95% CI −0.04 to 0.03), with almost no heterogeneity (I² 4%). The share of women enrolled in a trial did not change its results.

This matters because under-enrolment of women has been used as a reason, consciously or not, to hold back or under-dose guideline therapy in women. These data do not support that.

Prescribe guideline-directed heart failure therapy to women at the same doses as men.
Audit your clinic for women with reduced ejection fraction who are not on all four drug classes.
Titrate to target doses in women unless side effects or blood pressure limit it.
Keep encouraging women to join trials; sex balance still matters for safety signals.

Why it matters

Under-representation in trials is not a reason to under-treat women with heart failure.

The statistics, in plain English

A difference close to zero, with a narrow interval, means the trials found no gap between the sexes. An I² of 4% means the trials agreed with each other, which strengthens the conclusion.