Assignment to menopausal status and estimation of age at menopause for women with missing or invalid data - A probabilistic approach with weighting factors in a large-scale epidemiological study

Objective: Gynaecologic surgeries and hormone medication increasingly inter fere with the concept of determining menopausal status based on self-report ed data about the last menstrual period-an approach frequently applied in e pidemiological studies. This analysis compared different approaches of meno pausal status determination, including a probabilistic approach that was de veloped to reduce misclassification of menopausal status. Methods: Intervie w and questionnaire data relating to hormone status from about 16 000 Germa n women were used to determine menopausal status using different approaches : menses based, age based, self-assessment based, and a probabilistic appro ach. Results: Applying strict menses-based criteria, 29.1% of the women wer e found to be with undetermined menopausal status. The probabilistic approa ch was applied to determine menopausal status and age at menopause for thes e women. The proposed approach uses the current age of the women with undet ermined menopausal status, and the relative age-dependent frequencies of pr e- or postmenopausal status among those with natural menopausal status to c alculate weighting factors, which represent the probabilities of being pre- and postmenopausal of each woman previously undetermined. Correspondingly, the missing age at menopause was estimated with the same probabilistic app roach. Applying various approaches to determine menopausal status, the rati o of pre- to postmenopausal women differed considerably, ranging from 1.03 to 1.61. In addition, considerable differences were observed with respect t o the number of missing values for both menopausal status and age at menopa use. Conclusion: The probabilistic approach allowed to estimate menopausal status and age at menopause with the advantage that all available informati on from the entire study population and from the individual is used. (C) 20 01 Elsevier Science Ireland Ltd.