Reliability of Self-Reported Weight, Age at Menarche and Menopause, and Reason for Absence of Menses: A Cohort Study
Background: In epidemiological studies data on lifetime exposures are often self-reported. In this study we evaluate reliability of self-reported information on weight at eighteen years, age at menarche and menopause, and the reason for absence of menses. Furthermore we wanted to determine to what extent the reliability was affected by age, education and histo-pathological findings.
Methods: This study was conducted within the framework of the Diagnosis Optimization Study. The study population included all women who underwent image-guided core biopsy for evaluation of breast abnormality at University Hospital of Halle, Germany. A total of 1670 women reported their weight at 18, age at menarche and menopause in a questionnaire at baseline and at follow-up. Bland Altman plots were used for the reliability analyses, while linear regression analyses were performed to assess the factors that were independently associated with the reliability (measured by absolute differences). Results: Weight at age of 18 and age at menarche and menopause were reported on average with small differences. The differences in self-reported weight and age at menarche and menopause were greater in women with lower education. Furthermore selfreported weights were related to age – the difference increased with increasing age. The observed agreement for the reason for absence of menses was 0.92 (95% CI: 0.91-0.94), the chancecorrected agreement was 0.85 (95% CI: 0.82-0.88), respectively. Discussion: Our study provides evidence that women reported their weight at age 18 and age at menarche and age at menopause with good reliability. Furthermore, our results suggest that the reliability is positively associated with higher education and younger age. Therefore, our study results support the use of selfreported information with regard to weight at the age 18, age at menarche and menopause, and reason for absence of menses in epidemiological studies.