Carrasquilla GD, et al. - Herein, the authors coveted an analysis of the correlation between hormone therapy (HT) and risk of stroke, with regard to the timing of initiation, route of administration, type, active ingredient, and duration of HT. Irrespective of the route of administration, type of HT, active ingredient, and duration, no link was found between HT with an increased risk of incident stroke when initiated early in relation to menopause onset. This was true for haemorrhagic stroke. The initiation of HT 0–5 years after menopause onset, as compared to never use, exhibited a connection with a decreased risk of stroke and haemorrhagic stroke. Late initiation correlated with elevated risks of stroke and haemorrhagic stroke when conjugated equine oestrogen was used as single therapy. An association was brought to light between late initiation of combined HT with haemorrhagic stroke risk.

Methods

• This research consisted of data on HT use reported by the participants in 5 population-based Swedish cohort studies, with baseline investigations, during 1987-2002.
• Researchers examined 88,914 postmenopausal women who reported data on HT use and had no previous cardiovascular disease diagnosis.
• With the aid of national population registers, incident events of stroke (ischaemic, haemorrhagic, or unspecified) and haemorrhagic stroke were determined.
• Laplace regression aided in examining the crude and multivariable-adjusted associations between HT and stroke risk by estimating percentile differences (PDs) with 95% confidence intervals (CIs).
• The fifth and first PDs were computed for stroke and haemorrhagic stroke, respectively.
• Herein, the crude models were adjusted for age at baseline only.
• Age at baseline, level of education, smoking status, body mass index, level of physical activity, and age at menopause onset served as the final adjusted models.
• The type of menopause, parity, use of oral contraceptives, alcohol consumption, hypertension, dyslipidaemia, diabetes, family history of cardiovascular disease, and cohort were included as the additional variables evaluated for potential confounding.

Results

• A total of 6,371 first-time stroke events were recorded during a median follow-up of 14.3 years.
• Among these, 1,080 were found to be haemorrhagic.
• Following multivariable adjustment, early initiation (<5 years since menopause onset) of HT exhibited a link with a longer stroke-free period than never use (fifth PD, 1.00 years; 95% CI 0.42 to 1.57).
• However, no prominent extension was noted to the time period free of haemorrhagic stroke (first PD, 1.52 years; 95% CI -0.32 to 3.37).
• The stroke-free and the haemorrhagic stroke-free periods were maximal if HT was initiated approximately 0-5 years from the onset of menopause, taking into account the timing as a continuous variable.
• During the usage of single conjugated equine oestrogen HT, late initiation of HT displayed a connection with a shorter stroke-free (fifth PD, -4.41 years; 95% CI -7.14 to -1.68) and haemorrhagic stroke-free (first PD, -9.51 years; 95% CI -12.77 to -6.24) period than never use.
• A notable correlation was brought to light between combined HT when initiated late with a shorter haemorrhagic stroke-free period (first PD, -1.97 years; 95% CI -3.81 to -0.13), but not with a shorter stroke-free period (fifth PD, -1.21 years; 95% CI -3.11 to 0.68) than never use.
• The possibility of uncontrolled confounding could not be excluded due to the observational nature of this study.
• Additionally, immortal time bias, associated with the observational design, could not be ruled out.