Cohort studyindependent cross-checkabstract checked I-ORG-135 standard review
Ovary removal and death rates in Californian teachers
Bilateral oophorectomy is not associated with increased mortality: the California Teachers Study.
Overview
Duan L et al.. Fertil Steril 2012 · PMID 22088205 · DOI 10.1016/j.fertnstert.2011.10.004
Women whose menopause came from ovary removal did not die more often than women with natural menopause.
Does the study support the specific claim? No · Methodological quality: moderate
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Compare mortality after surgical vs natural menopause
- How was the study done?
Prospective cohort
- How many people, animals or samples were studied?
About 41,000 women
- What was actually found?
No increase in mortality
- How large was the observed effect?
All-cause RR 0.86-0.87
- What do the results mean in everyday life?
Shows the harm is not seen in every study
- What are the study's limitations?
Survivor bias, different comparator
- What does it say about Elawady's specific claim?
Contradicts the claim
- Do the results apply to Germany and Europe?
Applicable
- What can explicitly not be concluded from this study?
Cannot rule out harm in young women without estrogen
Scientific in-depth review
1. Full reference
- Authors
- Duan L et al.
- Journal
- Fertil Steril
- Year
- 2012
- Identifier
- PMID 22088205 DOI 10.1016/j.fertnstert.2011.10.004
- Verification
- verified – PubMed efetch 2026-10-26; Crossref works API 2026-10-26
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
NIH-funded (PubMed).
2. Research question
Is surgical menopause from bilateral oophorectomy associated with mortality compared with natural menopause?
3. Study design and population
- Study design
- Cohort study – Prospective cohort (California Teachers Study)
- Population
CTS participants with surgical (n = 9785) or natural menopause (n = 32,219)
- Country
USA (California)
- Period
Cohort from 1995-1996
- Sample size
41,004 analysed (from 133,479)
- Inclusion and exclusion criteria
Women reporting menopause type at baseline
4. Methods and endpoints
- Exposure / intervention
Bilateral oophorectomy (surgical menopause)
- Comparator
Natural menopause
- Endpoints
All-cause, cardiovascular, cancer mortality
- Statistical methods
Cox regression, multivariable RR
5. Actual results
- Results
Menopause < 45: all-cause RR 0.86 (0.74-1.00), CVD 0.85 (0.66-1.11), cancer 0.91 (0.67-1.23). Menopause >= 45: all-cause 0.87 (0.80-0.94), CVD 0.83 (0.71-0.96), cancer 0.84 (0.72-0.98). No difference by hormone therapy.
- Absolute risks
Not reported
- Authors' conclusion
Surgical menopause due to bilateral oophorectomy vs natural menopause does not increase mortality.
6. Strengths
- Large prospective cohort
7. Weaknesses
- Comparator is natural menopause, not ovarian conservation at hysterectomy
- Self-reported surgery
- Prevalent-user/survivor bias (baseline status)
- High estrogen use in cohort
8. Risk of bias
- Orienting tool
- ROBINS-E
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- high
- Rationale
Women alive at baseline after surgery (survivor bias); different comparator.
9. Assessment of the statistical interpretation
Point estimates below 1 suggest bias (healthy survivor) rather than true protection.
10. Relevance to the specific claim
Main contradicting cohort.
11. Independent contrary findings
Cusimano 2021 and Parker 2013 with better designs found harm in younger women.
12. Transferability to Germany and Europe
US; applicable.
13. Overall methodological judgement
Contradicts a general harm claim but is weaker than incident-exposure cohorts.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | moderate |
| Risk of bias | high |
| Precision of results | moderate |
| Directness | indirect |
| Reproducibility | not replicated |
| Consistency with the overall evidence | inconsistent |
| Regional transferability | high |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
n/a