Background: This paper presents the protocol of the 4 round of Iranian Multi-center Osteoporosis Study (IMOS), a national survey with the primary objective of estimating the prevalence of osteoporosis and sarcopenia and their risk factors in a representative sample of urban and rural populations.
Methods: The target population of the survey is all individuals ≥ 50 years in Iran. A multi-stage random sampling method has been used in the study.