2.1. Protocol for the literature search
A protocol for the systematic assessment of the literature on the prevalence of OFC in Saudi Arabia and other Middle Eastern countries was developed. The Middle Eastern countries included were: Jordan, Syria, UAE, Qatar, Kuwait, Bahrain, Oman, and Yemen. All of these countries border Saudi Arabia. The populations of these countries are comparable to the Saudi population in terms of the following characteristics: ethnic group, religion, tradition, culture, high rate of consanguineous marriage, and high birth rate. Iraq was excluded because of the suspected high prevalence of teratogenic defects resulting from long-term conflict (Fathallah, 2007
The literature search protocol that was formulated consisted of the following: keyword identification, development of a search strategy, selection of search engines, and definition of inclusion/exclusion criteria for identified studies. The search strategy consisted of combinations of three keyword groups: (1) prevalence, epidemiology; (2) orofacial cleft, cleft palate, cleft lip, craniofacial anomalies; and (3) Jeddah, Riyadh, Saudi Arabia, Middle East, Arabia, Jordan, Syria, United Arab Emirates, UAE, Qatar, Kuwait, Bahrain, Oman, and Yemen. The search engines used were PubMed and Scopus. In addition, certain keywords were used to search Google (from the year 1980 to 2010), the Saudi Dental Journal (SDJ), the Saudi Medical Journal (SMJ), Jordan Medical Journal, Syrian American Medical Journal, Avicenna Journal of Medicine, Syria Medical Journal, Kuwait Medical Journal, International Arab Journal, Oman Medical Journal, Yemeni Journal for Medical Sciences, Bahrain Medical Bulletin, Journal of Bahrain Medical Society, and Qatar Medical Journal. The searches were performed in July 2010. All papers were obtained, websites were checked, and references for articles and websites were reviewed for other relevant articles and abstracts. The search did not exclude any languages. In cases where data were reported in more than one article, the data were only extracted once.
2.2. Inclusion and exclusion criteria for studies
All papers were reviewed for studies meeting the following inclusion criteria:
• The study reported data on the prevalence of cleft lip and palate in Saudi Arabia or one of the countries in the Middle East listed above.
• If the prevalence of cleft lip and palate was not included in the paper, then sufficient information to calculate an approximate prevalence of OFC was required. For instance, the timing and methods used for data collection and the sample size were required to allow for an estimation of the denominator size of the base population.
The exclusion criteria for studies were the following:
• The prevalence of OFC was not reported and could not be estimated from the presented data.
• The article reported information on the prevalence of craniofacial anomalies as a whole, but did not specify the prevalence of OFC.
• The study did not present sufficient details on the materials and methods.
2.3. Data extraction
Papers meeting the inclusion criteria were reviewed, and when available the following data were extracted independently and in duplicate by two of the authors (HS and NI):
• dates, geographic location, and design of the study;
• sample size, source of population, and nationalities;
• demographic data of the sample;
• prevalence of cleft lip and/or palate; and
• prevalence of cleft lip and/or palate according to sex, consanguineous marriage rate, the presence of positive family history, and the association of other deformities.
The prevalence of OFC from each study was recorded, and the mean was compared with global prevalence figures.