Evidence Table 10Patient Risk Factors – hormone replacement therapy

Bibliographic referenceStudy TypeEvidence levelNo. of patientsPatients characteristicsExposureLength of follow up/exposureOutcome measuresEffect sizeComments
Miller et al., 2002444Systematic review

12 studies
3 RCTs
1 cohort
8 case- control studies
2+RCTs: 3919
Cohort studies: 476,008
Case- control studies: 22,137
Post-menopausal women

women with a history of thrombotic events or conditions associated with high risk for thrombosis

Women in 1 RCT were healthy
Women in 2 RCTs had heart disease

Health status not recorded for cohort or case control studies
Hormone replacement therapy

Post menopausal oestrogen replacement

Oestrogen alone or oestrogen plus progestin

RCTs and the cohort study were outpatient studies. The RCTs used a placebo for the control group.

4 case control studies used hospital based controls
4 case control studies used population based controls
Not reported for all studies.

RCTs: one not specified, other two 3 or 4 years.

Cohort: compared >5 year use with < 5years

Case controls: not reported
Risk estimate for venous thromboembolismRelative risk: 2.14
Cred Int: 1.64 to 2.81
(all studies)
Mehtod of diagnosis for thromboembolism diagnosis varied. Most rigorous venography, ultrasonography or Doppler ultrasonography for DVT, venography or perfusion scan for PE. 3 studies did not state the method of diagnosis.

Relative risks and credible intervals (Cred Int) calculated using a bayesian meta- analysis.
Risk estimate venous thromboembolismRelative risk: 3.75
Cred Int: 1.23 to 10.26
(3 RCTs)
Risk estimate venous thromboembolismRelative risk: 2.1
Cred Int: 1.2 to 3.8
(1 cohort study)
Risk estimate venous thromboembolismRelative risk: 2.05
Cred Int: 1.40 to 2.95
(8 case control studies)
Risk estimate venous thromboembolism first year use vs subsequent yearsRelative risk in 1st year of use: 3.49
Cred Int: 2.33 to 5.59
Relative risk after 1 year of use:: 1.91
Cred Int: 1.18 to 3.52
(6 studies)
Rocha et al., 2007556Systematic review

6 studies

3 RCTs

3 case control studies
2+UnclearPost-menopausal womenHormone replacement therapyNot reported for all studies.Risk estimate for VTE in group receiving HRT compared with placebo groupRelative risk: 2.1
(95% CI 1.6–2.8)

(1 RCT)
Definition and diagnosis of VTE not provided.

Only results presented are those not already reported in Miller et al. 2002444
Risk estimate for VTE with oral administration of HRT (compared to transdermic administration)Odds ratio: 4.0
(95% CI 1.9 – 8.3)

(1 study)
Royal College of Obstetricians and Gynaecologists, 2004562System atic review including 9 studies2+Not reportedWomen on hormone replacement therapy

Exact inclusion/exclusion criteria not reported.
Hormone replacement therapy (oestrogen)

No description of the control groups
Not reportedRisk estimates reported for each study, no pooled estimateRelative risks varied from: 1.22 up to 6.9

From: Appendix D, Evidence tables

Cover of Venous Thromboembolism
Venous Thromboembolism: Reducing the Risk of Venous Thromboembolism (Deep Vein Thrombosis and Pulmonary Embolism) in Patients Admitted to Hospital.
NICE Clinical Guidelines, No. 92.
National Clinical Guideline Centre – Acute and Chronic Conditions (UK).
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