Postmenopausal women who took hormone replacement therapy (HRT) had fewer cardiovascular risk factors to start with than women who do not, a Swedish longitudinal study has determined (BMJ 1999;319:890-3). This means that the lower rates of cardiovascular disease found in women taking HRT could be attributable to better cardiovascular health, not HRT. In a result that is sure to be controversial, the study's authors conclude that it is premature to recommend HRT for the prevention of cardiovascular disease.
The study followed 1201 women for 24 years, of whom 15% eventually used HRT. Those who used it had significantly lower blood pressure and were less likely to be obese. HRT users were also more physically active and had higher social status than nonusers.
Dr. Kerstin Rödström of Gothenburg, Sweden, the report's principal author, is critical of previous studies showing a cardioprotective effect of HRT-as much as 50% risk reduction in some studies. "HRT might have a protective effect, but we think this has been exaggerated. In previous observational studies, there might be a selection bias due to higher education, higher economic status and a healthier cohort in HRT users, which are associated with fewer risk factors for CVD."
The cohort of women studied in Sweden has been extensively studied, but Rödström says that there are too few hard end points yet to allow the researchers to find associations between cardiovascular disease in the cohort and risk factors.
What does this mean to physicians counselling patients about HRT? Rödström believes HRT still offers benefits in terms of osteoporosis prevention. "If a woman asks for HRT, look at the benefits and risks. If she doesn't have menopausal symptoms and only wants to have HRT as primary prevention for CVD, I would tell her that it is too early to recommend HRT for this."