Further analysis revealed that the relative risks or protection hormone therapy conferred depended on how long after menopause women started treatment.
Mortality was reduced 30% and coronary heart disease was reduced 48% in women who began hormone therapy less than 10 years after menopause (RR 0.70 and RR 0.52, respectively); these women still faced a 74% increased risk of venous thromboembolism, but no increased risk of stroke.
Meanwhile, women who started hormone therapy more than 10 years after menopause had a 21% increased risk of stroke and a 96% increased risk of venous thromboembolism, but no reduced risk on overall death or coronary heart disease.
“It is worth noting that the benefit seen in survival and coronary heart disease for the group starting treatment less than 10 years after the menopause is from combining five trials all performed in primary prevention populations and all with quite long follow-up, ranging from 3.4 to 10.1 years,” the authors wrote.
These results may reflect the possibility of a time interaction, with coronary heart disease events occurring earlier in predisposed women, making it impossible to say whether short duration therapy is beneficial in this population or not, the researchers wrote .
Eighteen of the 19 trials included in the analysis reported the funding source. One study was exclusively funded by Wyeth-Ayerst. Two studies received partial funding from Novo-Nordisk Pharmaceutical, and one study was funded by the National Institutes of Health with support from Wyeth-Ayerst, Hoffman-LaRoche, Pharmacia, and Upjohn. Eight other studies used medication provided by various pharmaceutical companies.