Exploring the extent of postmenopausal osteoporosis among Saudi Arabian women using dynamic simulation.

The prevalence of postmenopausal osteoporosis among Saudi Arabian women is difficult to estimate because it is a large country with a diverse widely dispersed population. There have been reports of localized prevalence estimates but these are difficult to compare. In the absence of reliable national data, a theoretical approach may be useful. We have extended our mathematical model of the WHO scheme for osteoporosis diagnosis so that it is capable of predicting the prevalence of postmenopausal osteoporosis in a population of women on a year-by-year basis. These calculations are based on the area under a theoretical Gaussian bone mineral density (BMD) distribution bounded by the WHO thresholds for osteoporosis and osteopenia. This simulation approach confirms the pivotal role played by the standard deviation of BMD in the young, healthy normal reference group and it permits the model's sensitivity to other parameters (amplitude and time constant of the postmenopausal decline in BMD) and circumstances (age-related changes in standard deviation) to be accurately quantified: For Saudi Arabian women aged 50-70 yr, we estimate the prevalence of osteoporosis to be approximately 23%. The precise value depends strongly on the underlying standard deviation of BMD across the various age groups, which still remains to be accurately determined within the Saudi Arabian population.