[Using parametric and non-parametric methods to estimate the pattern of the age at natural menopause based on prevalence data]

Various studies have reported different ages of menopause in Iran, from 46 to 51 years. This broad range of age at menopause cannot be attributed solely to the difference between women of different regions, but could also be related to methodological problems. The model of menopausal age could be estimated by a cohort study or a cross-sectional survey and each method has advantages and disadvantages. In cross-sectional studies, the target is only the status of menstruation for each woman, such that the prevalence of menopause can be calculated in each age group. Therefore, the pattern of the age at menopause cannot be estimated using the prevalence data. For estimating the patterns of the age at natural menopause and its characteristics, parametric and non-parametric methods were utilized and the data from the survey: "Estimating the pattern of the age at natural menopause and its effective factors in Semnan" was used to illustrate these two methods. In that survey, during the year 2007, 3545 urban and rural women were randomly selected and their status in terms of menopause was asked, then by excluding abnormal menopause, 3404 had been selected for the study. The pattern of menopause age was obtained with the help of generalized linear models [GLM] with parametric base and compared with non-parametric method in which the probability distribution is estimated empirically. By applying and comparing the two parametric and non-parametric methods the method that provides better natural menopause age model was clarified. Although there were not many differences between the estimated values in the different models, but the log-log model provided a more accurate estimation than the two-parametric, logistic and probit models and its results were similar to the non-parametric model. It seems, logistic model is more appropriate than other models to estimate the pattern of the age at natural menopause, although further research is needed

[ pattern of the age at natural menopause in Semnan Province, Iran]

To study the pattern of age at menopause in Semnan Province, Iran. A total 3545 women, 30 years or older, were selected using a cluster random sampling method and interviewed to fill out a questionnaire. Since the object of the study was determination of the pattern of age at natural menopause, some cases with abnormal, operative and so on, ignored and finally 3404 women were enrolled in the study and the pattern of the age at menopause was estimated using prevalence of menopause in each age group. The total mean and median of age at natural menopause were 52.40 5.02 and 50.40, respectively. Increasing of menopause was slow from age 30 to 43, but its speed increased until 55 years old, then decreased slowly. compared to the other regions of Iran, the mean of age at natural menopause in Semnan seems higher