Objective: To determine the age-specific and age-adjusted prevalence of osteopenia and osteoporosis in pre-and postmenopausal Thai women.

Methods: This was a descriptive study of 1,935 Thai women ranging in age from 40 to 80 years, with randomly selected strata using multistage sampling and stratifying from six representative provinces of the country. After recruiting, all the women were interviewed by a well-trained interviewer using structured questionnaires. Bone mineral density (BMD) of lumbar spine 1-4 and nondominant hip was measured by a dual energy photon absorptiometer. The investigators were trained and standardized; inter-and intraobserver variations were measured periodically. Every BMD outcome was re-examined by the specialist. Age-specific prevalence of osteoporosis and osteopenia were determined using both Thai and Western standard BMD values. Age-adjusted prevalence of osteopenia and osteoporosis was calculated using the age-adjusted direct method.

Results: Using the Thai BMD reference, the age-specific prevalence of osteoporosis among Thai women rose progressively with increasing age to more than 50% after the age of 70. The age-adjusted prevalence of osteoporosis also rose progressively. It was 19.8%, 13.6%, and 10% for lumbar spine, femoral neck, and intertrochanteric. The age-adjusted prevalence of osteoporosis indicates the overall magnitude of that condition in the population or country. In our study, using a Western BMD reference resulted in a misleadingly high prevalence of osteoporosis in the population of Asian countries.

Conclusion: It is important to calculate the age-adjusted prevalence of osteopenia and osteoporosis to address the overall magnitude of the problem in Thai women. This will allow us to predict the socioeconomic impact of preventable chronic conditions such as osteoporosis. The results obtained from this study are important data for public health policy: maximizing bone mass throughout life as well as detection of important risk factors is essential.