Age at menopause in women participating in the postmenopausal estrogen/progestins interventions (PEPI) trial: An example of bias introduced by selection criteria

PEPI trail investifators, Susan Miller

Research output: Contribution to journalArticle

Abstract

Our objective is to illustrate the bias introduced in assessing factors associated with age at menopause when the population sample has been selected using restricted criteria, i.e. number of years since menopause, by using a cross-sectional analysis of baseline data from a population-based randomized clinical trial. The participants were women who participated in the Postmenopausal Estrogen/Progestins Intervention (PEPI) trial, had not had a hysterectomy, were between 45 and 64 years old, and were menopausal for at least 1 but not greater than 10 years. The outcome measures were self-reported age at menopause and factors thought to be associated with it, including smoking, alcohol use, oral contraceptive use, number of pregnancies, education, income, body mass index, waist-hip ratio, thigh girth, and systolic and diastolic blood pressures. At entry, the mean age of the 601 women was 56.2 years. Mean age at menopause was 51.0 years. Chronologic (current) age was strongly correlated with age at menopause (r = 0.74, p = 0.0001). In bivariate analyses, factors associated with younger age at menopause were ever-use of cigarettes, former oral contraceptive use, and higher thigh girth; factors associated with later age at menopause were greater number of pregnancies, higher waist-hip ratio, and higher systolic blood pressure. After stratification by 5-year age intervals, these associations were no longer statistically significant. Because of restricted sampling, an artificial association was observed between chronologic age and age at time of menopause. This artifact made it difficult to distinguish between factors associated with chronologic age and those that may be independently associated with menopause. Failure to recognize this bias could lead to erroneous conclusions.

Original languageEnglish (US)
Pages (from-to)27-34
Number of pages8
JournalMenopause
Volume2
Issue number1
StatePublished - 1995

Fingerprint

Progestins
Menopause
Patient Selection
Estrogens
Waist-Hip Ratio
Oral Contraceptives
Thigh
Blood Pressure
Pregnancy
Hysterectomy
Tobacco Products
Artifacts
Population
Statistical Factor Analysis
Body Mass Index
Randomized Controlled Trials
Cross-Sectional Studies
Smoking
Alcohols
Outcome Assessment (Health Care)

Keywords

  • Ovarian aging
  • Ovary
  • Randomized clinical trial
  • Risk factors
  • Sampling bias

ASJC Scopus subject areas

  • Obstetrics and Gynecology

Cite this

Age at menopause in women participating in the postmenopausal estrogen/progestins interventions (PEPI) trial : An example of bias introduced by selection criteria. / PEPI trail investifators; Miller, Susan.

In: Menopause, Vol. 2, No. 1, 1995, p. 27-34.

Research output: Contribution to journalArticle

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title = "Age at menopause in women participating in the postmenopausal estrogen/progestins interventions (PEPI) trial: An example of bias introduced by selection criteria",
abstract = "Our objective is to illustrate the bias introduced in assessing factors associated with age at menopause when the population sample has been selected using restricted criteria, i.e. number of years since menopause, by using a cross-sectional analysis of baseline data from a population-based randomized clinical trial. The participants were women who participated in the Postmenopausal Estrogen/Progestins Intervention (PEPI) trial, had not had a hysterectomy, were between 45 and 64 years old, and were menopausal for at least 1 but not greater than 10 years. The outcome measures were self-reported age at menopause and factors thought to be associated with it, including smoking, alcohol use, oral contraceptive use, number of pregnancies, education, income, body mass index, waist-hip ratio, thigh girth, and systolic and diastolic blood pressures. At entry, the mean age of the 601 women was 56.2 years. Mean age at menopause was 51.0 years. Chronologic (current) age was strongly correlated with age at menopause (r = 0.74, p = 0.0001). In bivariate analyses, factors associated with younger age at menopause were ever-use of cigarettes, former oral contraceptive use, and higher thigh girth; factors associated with later age at menopause were greater number of pregnancies, higher waist-hip ratio, and higher systolic blood pressure. After stratification by 5-year age intervals, these associations were no longer statistically significant. Because of restricted sampling, an artificial association was observed between chronologic age and age at time of menopause. This artifact made it difficult to distinguish between factors associated with chronologic age and those that may be independently associated with menopause. Failure to recognize this bias could lead to erroneous conclusions.",
keywords = "Ovarian aging, Ovary, Randomized clinical trial, Risk factors, Sampling bias",
author = "{PEPI trail investifators} and Greendale, {Gail A.} and Patricia Hogan and Donna Kritz-Silverstein and Robert Langer and Johnson, {Susan R.} and Trudy Bush and Miller, {Valery T.} and Craig Kessler and John LaRosa and Stoy, {Diane B.} and Ginny Levin and Ann Smith-Roth and Margaret Griffin and Zacur, {Howard A} and David Foster and Jean Anderson and Susan Miller and Susan Miller and Allison Akana and {LeRoy Heinrichs}, W. and Charlene Kirchner and Katherine O'Hanlan and Melissa Ruyle and Howard Judd and Richard Buyalos and Kathy Lozano and Kathy Kawakami and Elizabeth Barrett-Connor and Lou, {Mary Carrion Peterson} and Carmela Cavero and Schrott, {Helmut G.} and Feddersen, {Deborah A.} and Krutzfeldt, {Denise L.} and Ann, {Jo Benda} and Carl Pauerstein and Jose Trabel and Robert Schenken and Michael Stern and Mercedes Rodriguez-Sifuentes and Carann Easton and {Bradley Wells}, H. and Mark Espeland and George Howard and Bob Byington and Claudine Legault and Sally Shumaker and Don Hire and Carol Wasilauskas and Kathy Lane and Stephanie Aycock",
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T2 - An example of bias introduced by selection criteria

AU - PEPI trail investifators

AU - Greendale, Gail A.

AU - Hogan, Patricia

AU - Kritz-Silverstein, Donna

AU - Langer, Robert

AU - Johnson, Susan R.

AU - Bush, Trudy

AU - Miller, Valery T.

AU - Kessler, Craig

AU - LaRosa, John

AU - Stoy, Diane B.

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AU - Smith-Roth, Ann

AU - Griffin, Margaret

AU - Zacur, Howard A

AU - Foster, David

AU - Anderson, Jean

AU - Miller, Susan

AU - Miller, Susan

AU - Akana, Allison

AU - LeRoy Heinrichs, W.

AU - Kirchner, Charlene

AU - O'Hanlan, Katherine

AU - Ruyle, Melissa

AU - Judd, Howard

AU - Buyalos, Richard

AU - Lozano, Kathy

AU - Kawakami, Kathy

AU - Barrett-Connor, Elizabeth

AU - Lou, Mary Carrion Peterson

AU - Cavero, Carmela

AU - Schrott, Helmut G.

AU - Feddersen, Deborah A.

AU - Krutzfeldt, Denise L.

AU - Ann, Jo Benda

AU - Pauerstein, Carl

AU - Trabel, Jose

AU - Schenken, Robert

AU - Stern, Michael

AU - Rodriguez-Sifuentes, Mercedes

AU - Easton, Carann

AU - Bradley Wells, H.

AU - Espeland, Mark

AU - Howard, George

AU - Byington, Bob

AU - Legault, Claudine

AU - Shumaker, Sally

AU - Hire, Don

AU - Wasilauskas, Carol

AU - Lane, Kathy

AU - Aycock, Stephanie

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N2 - Our objective is to illustrate the bias introduced in assessing factors associated with age at menopause when the population sample has been selected using restricted criteria, i.e. number of years since menopause, by using a cross-sectional analysis of baseline data from a population-based randomized clinical trial. The participants were women who participated in the Postmenopausal Estrogen/Progestins Intervention (PEPI) trial, had not had a hysterectomy, were between 45 and 64 years old, and were menopausal for at least 1 but not greater than 10 years. The outcome measures were self-reported age at menopause and factors thought to be associated with it, including smoking, alcohol use, oral contraceptive use, number of pregnancies, education, income, body mass index, waist-hip ratio, thigh girth, and systolic and diastolic blood pressures. At entry, the mean age of the 601 women was 56.2 years. Mean age at menopause was 51.0 years. Chronologic (current) age was strongly correlated with age at menopause (r = 0.74, p = 0.0001). In bivariate analyses, factors associated with younger age at menopause were ever-use of cigarettes, former oral contraceptive use, and higher thigh girth; factors associated with later age at menopause were greater number of pregnancies, higher waist-hip ratio, and higher systolic blood pressure. After stratification by 5-year age intervals, these associations were no longer statistically significant. Because of restricted sampling, an artificial association was observed between chronologic age and age at time of menopause. This artifact made it difficult to distinguish between factors associated with chronologic age and those that may be independently associated with menopause. Failure to recognize this bias could lead to erroneous conclusions.

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KW - Ovarian aging

KW - Ovary

KW - Randomized clinical trial

KW - Risk factors

KW - Sampling bias

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