Table 2.
Summary of cohort studies
| Study | Objective | Country | Type of HRT | Sample size | Attrition | Method | Statistical results | Conclusion |
|---|---|---|---|---|---|---|---|---|
| Zandi et al (2002)8 | Reducing risk of Alzheimer's disease | USA | Oral oestrogen preparation | 5092 | 1846 (36.3%) | Current/former user or never used via history | Relative risk 0.34 (odds ratio 0.32 [95% CI 0.20–0.51]) | Duration of HRT use is associated with decreasing Alzheimer's disease risk |
| Yoo et al (2020)12 | Reducing risk of Alzheimer's disease | Korea | Not collecteda | 4 696 633 | 0% | Survey | Relative risk 0.52 (odds ratio 0.51 [95% CI 0.51–0.52]) | Use of HRT is associated with reduced Alzheimer's disease risk |
| Paganini-Hill and Henderson (1994)13 | Reducing risk of Alzheimer's disease | USA | Oral oestrogen (1.25 mg) | 688 | 7 (1.02%) | Survey | Relative risk 0.75 (odds ratio 0.67 [95% CI 0.38–1.17]) | No significant findings that oestrogen replacement therapy may be useful for preventing and delaying onset of Alzheimer's disease |
| Tang et al (1996)16 | Reducing risk of Alzheimer's disease | USA | Oral CEE | 1124 | 0% | Current/former user or never used via history | Relative risk 0.40 (odds ratio 0.31 [95% CI 0.16–0.63]) | History of oestrogen use during post-menopausal period delays onset of Alzheimer's disease and lowers risk of disease |
| Lord et al (2008)17 | Prevention of Alzheimer's disease (neuroprotective effects of oestrogen replacement therapy) | Canada | CEE or oestradiol therapy (oral or transdermal) | 56 | 0% | Telephone interviews and questionnaires | Not applicable | Oestrogen replacement therapy is neuroprotective |
| Kawas et al (1997)23 | Reducing risk of Alzheimer's disease | USA | Oral or transdermal oestrogen | 514 | 42 (8%) | Current/former user or never used via history | Relative risk 0.46 (odds ratio 0.42 [95% CI 0.20–0.92]) | Reduced risk of Alzheimer's disease for women who had reported the use of oestrogen |
| Baldereschi et al (1998)24 | Prevention of Alzheimer's disease | Italy | Not collecteda | 2727 | 1159 (42.5%) | Survey | Relative risk 0.25 (odds ratio 0.24 [95% CI 0.07–0.77]) | Oestrogen replacement therapy is associated with a reduced prevalence of Alzheimer's disease in post-menopausal women |
| Imtiaz et alb (2017)27 | Reducing risk of Alzheimer's disease | Finland | Oestrogen or combination therapy | 8195 | 0% | Questionnaires | Relative risk 0.98c | Long-term oestrogen replacement therapy use reduces risk of Alzheimer's disease |
| Mortel and Meyer (1995)33 | Reducing risk of Alzheimer's disease | USA | Not collecteda. | 306 | Undisclosed | Medical records, questionnaires, interviews | Relative risk 0.67 (odds ratio 0.55 [95% CI 0.26–1.16]) | Oestrogen replacement therapy reduces risk of Alzheimer's disease |
HRT, hormone replacement therapy; CEE, conjugated equine oestrogen.
a.
Unable to contact authors for further clarification.
b.
Note that this study is a different study from the Imtiaz et al15 case–control study.
c.
Data to calculate odds ratio was not available.