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Importance: Knowing the scale of rare inborn errors is important for screening and resource allocation. Evidence on the prevalence of methylmalonic acidemia (MMA) among newborns and the clinical-suspected population from large-scale screening programs needs to be systematically synthesized. Objective: To estimate the worldwide prevalence of MMA for newborns and the clinical-suspected population and explore the differences in different regions, periods, and diagnostic technologies. Data sources MEDLINE, Embase, CRD, Cochrane Library, Scopus, CINAHL, and PROSPERO. Study Selection: All studies reporting the epidemiology characteristics of MMA were selected. Data extraction and synthesis Characteristics of study, subjects, and epidemiology were extracted, random-effect models were used for meta-analyses. Main outcome and measure Pooled prevalence of MMA. Results This study included 111 studies. The pooled prevalence of MMA worldwide was 1.14 per 100,000 newborns (1516/190,229,777 newborns, 95% CI: 0.99–1.29) and 652.11 per 100,000 clinical-suspected patients (1360/4,805,665 clinical-suspected individuals, CI: 544.14–760.07). Asia and Africa got a higher pooled prevalence of MMA. The prevalence of MMA in newborns increased through the years, while that in the clinical-suspected population decreased. Collecting blood ≥ 72 h after birth had a higher pooled prevalence of MMA than collecting during 24 h–72 h after birth. The combining-use of MS/MS and GC/MS had a higher pooled prevalence than the single-use of MS/MS or GC/MS. Prevalence of cbl C, mut, cbl B, cbl A, isolated MMA, combined MMA and homocystinuria, vitamin B12-responsive MMA was synthesized. Conclusions and relevance Prevalence of MMA among newborns was extremely low, but considerably high in the clinical-suspected population, indicating the need for more efficient newborn screening strategies and closer monitoring of the high-risk population for the early signs of MMA. Asia and Africa should attach importance to the high prevalence of MMA. Further diagnostic tests were recommended for the combining-use vs single-use of MS/MS and GC/MS and for collecting blood after 72 h vs during 24–72 h after birth. [ABSTRACT FROM AUTHOR]

Background: Particularly in developing countries, lower birthweight may be associated with higher neonatal mortality, and deliveries frequently take place at home where scales are not always available. Therefore, surrogate measurements for birthweight are necessary as a primary screening measure. The aim of this study was to determine whether newborn chest and arm circumferences can predict birthweight less than 2000 g., Methods: The selection criteria were studies published in English that could provide all the true- and false-positive and true- and false-negative results with regard to the prediction of birthweight less than 2000 g by other anthropometric measurements among apparently healthy neonates. Ten bibliographic databases (e.g., PubMed) were searched and a bivariate meta-analysis was conducted with hierarchical summary receiver operating characteristic (ROC) curves. A total of 36,987 participants in 24 studies for chest circumference and 16,164 participants in 15 studies for arm circumference were included. The study regions were limited to Africa and Asia., Results: For chest and arm circumferences (24 and 15 studies, respectively), pooled sensitivity (0.94 and 0.89, respectively) and specificity (0.94 and 0.96, respectively), and diagnostic odds ratios (263 and 174, respectively) were sufficiently high to allow good predictions. The diagnostic odds ratio for chest circumference was significantly higher than for arm circumference (P<0.001). The generalizability of the findings is to some extent guaranteed., Conclusion: Newborn chest and arm circumferences may be useful predictors of birthweight less than 2000 g, with chest circumference possibly better., (Copyright © 2014 Elsevier Masson SAS. All rights reserved.)