Background: Postmenopausal hormone therapy (HT) increases the risk of stroke. Here we evaluate whether leisure time physical activity (LTPA) can change stroke risk in women using HT, leveraging data from the California Teachers Study. Methods: Female California educators without a prior history of stroke (n = 118,294) were followed from 1995 through 2015 for stroke end points. Based on statewide hospitalization data, 4,437 women had ischemic (n = 3,162; International Classification of Diseases [ICD]-9 433, 434, 436) or hemorrhagic (n = 1,275; ICD-9 430-432, excluding 432.1) stroke. LTPA and HT use were evaluated at 2 time points (baseline [1995-1996] and 10-year follow-up [2005-2006]). LTPA was assessed using American Heart Association (AHA) recommendations (>150 min/week moderate or >75 min/week strenuous physical activity). Using multivariable Cox proportional hazards models, we estimated the hazard ratios (HRs) and 95% CIs for the associations between HT use and concurrent LTPA with incident stroke. Results: Compared to women who never used HT, stroke risk was highest among women who were current HT users and did not meet AHA recommendations for LTPA at the time of their HT use: HRbaseline 1.28 (95% CI 1.13-1.44); HR10-year follow-up 1.17 (95% CI 0.91-1.50). Based on the baseline questionnaire, current HT users who met AHA recommendations for LTPA in 1995-1996 still had elevated stroke risk in the 20-year follow-up (HR 1.22, 95% CI 1.08-1.37). However, among current HT users who met AHA recommendations for LTPA at the 2005-2006 follow-up questionnaire, stroke risk was not elevated (HR 1.01, 95% CI 0.80-1.29). Evaluation of the 2 time points in concert further demonstrated that meeting AHA recommendations for LTPA at the most recent follow-up time point was required to reduce HT-related stroke risk. Conclusion: Concurrent physical activity may attenuate the short-term increase in risk of stroke risk associated with HT use.
Bibliographical noteFunding Information:
This work was supported in part by federal funds from the National Institute of Neurological Diseases and Stroke under R21NS075608. The CTS and the research reported in this publication were supported by the National Cancer Institute of the National Institutes of Health under award number U01-CA199277; P30-CA033572; P30-CA023100; UM1-CA164917; and R01-CA077398. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Cancer Institute or the National Institutes of Health. The opinions, findings, and conclusions expressed herein are those of the author(s) and do not necessarily reflect the official views of the State of California, Department of Public Health, the National Cancer Institute, the National Institutes of Health, or their Contractors and Subcontractors, or the Regents of the University of California, or any of its programs.
- Hormone therapy
- Physical activity
- Stroke epidemiology