National and sub-national burden of oral diseases in Iran: 1990 - 2013, study protocol.

BACKGROUND Non-communicable chronic diseases are the greatest preventable cause of death. One of the most prevalent groups of chronic diseases, are oro-facial diseases. The major burden of oral diseases is caused by dental caries, periodontal diseases, tooth loss, oral cancer and oral clefts. The aim of the study is to present data collection and methodology processes for estimating the prevalence of the mentioned oral diseases and their attributed burden at national and sub-national levels in Iran, from 1990 to 2013. METHODS Systematic review of published literature will be conducted, as well as using unpublished and grey literature. Three international databases (PubMed, ISI and Scopus) and three local databases (IranMedex, SID and Irandoc) will be used to provide the most comprehensive epidemiologic data bank. The study will be included if it is population-based and has reported diseases data. The target population is representative healthy Iranian population. A comprehensive assessment form in Epi-Info 7 will be designed to assess the quality of selected articles. Other main sources of data are National Oral Health surveys, "National Health Survey", in addition to "Death Registry System" and "Cancer Registry System". Two statistical models, Spatio-temporal Bayesian hierarchical and Bayesian multilevel auto-regressive, will be applied to overcome the problem of data gaps in provinces, and in some age or sex groups or in urban and rural areas. CONCLUSION A national and sub-national oral diseases burden study needs a standardized protocol for systematic review, quality assessment of data, data extraction strategy, and an appropriate statistical analysis method.