Iodine deficiency in women of childbearing age in Brazil: systematic review and meta-analysis
Background: Despite current policies of salt iodination, iodine deficiency is still a global public health problem, especially in women. So far, conflicting evidence has been suggested for the prevalence of iodine deficiency in Brazil. Objective: To estimate the prevalence of iodine deficiency and associated factors in women of childbearing age in Brazil. Methods: A systematic review was conducted using databases (PubMed, LILACS, WHO, Scopus, and Capes’ dissertation and thesis), from inception to May 2020. Meta-analyses of proportions were performed using the variance inverse for the fixed model. Reporting and methodological quality were assessed using the Joanna Briggs Institute tool to prevalence studies. Results: Our review identified seven studies published between 2002 e 2017, including 1354 participants, especially pregnant women. All studies presented at least one quality limitation, mainly regarding the sampling method (i.e., convenience) and small sample size. The prevalence of iodine deficiency ranged among studies from 16% to 62%. In contrast, the meta-analysis identified a mean prevalence of 40% (95% confidence interval, CI 37%-43%) for pregnant women and 13% (95% CI 4%-24%) for non-pregnant women. Cumulative meta-analysis suggests a tendency of higher iodine deficiency prevalence from 2018 in pregnant women. Conclusions: Although this systematic review identified studies with poor methodological and reporting quality, a high prevalence of iodine deficiency was identified in pregnant women, reinforcing the importance of national nutritional policies for monitoring iodine status in this population. Future studies should consider random probabilistic sampling, appropriate sample size, and pre-defined subgroup analysis to adequately inform the prevalence of iodine deficiency and associated factors in women of childbearing age and support health policies.
Darnton-Hill I., Mkparu U. Micronutrients in Pregnancy in Low- and Middle-Income Countries. Nutrients 2015;7(3):1744–68. DOI: https://doi.org/10.3390/nu7031744.
Linhares DPS., Garcia PV., Almada A., et al. Iodine environmental availability and human intake in oceanic islands: Azores as a case-study. Sci Total Environ 2015;538:531–8. DOI: https://doi.org/10.1016/j.scitotenv.2015.08.109.
Zimmermann MB., Andersson M. Update on iodine status worldwide. Curr Opin Endocrinol Diabetes Obes 2012;19(5):382–7. DOI: https://doi.org/10.1097/MED.0b013e328357271a.
Brasil. Decreto no 39.814, de 17 de Agosto de 1956: Delimita as áreas bocígenas do Brasil, dispõe sobre o uso do sal iodado e dá outras providências. n.d.:Diário Oficial da União-Seção 1-20/8/1956; Pág.
Andersson, Maria, Bruno de Benoist, Ian Darnton-Hill FD. Iodine deficiency in Europe : a continuing public health problem. WHO 2007. Available at: https://www.who.int/nutrition/publications/VMNIS_Iodine_deficiency_in_Europe.pdf. Accessed June 22, 2021.
Glinoer D. The Regulation of Thyroid Function in Pregnancy: Pathways of Endocrine Adaptation from Physiology to Pathology. Endocr Rev 1997;18(3):404–33. DOI: https://doi.org/10.1210/edrv.18.3.0300.
Zimmermann MB., Gizak M., Abbott K., Andersson M., Lazarus JH. Iodine deficiency in pregnant women in Europe. Lancet Diabetes Endocrinol 2015;3(9):672–4. DOI: https://doi.org/10.1016/S2213-8587(15)00263-6.
Candido AC., Morais N de S de., Dutra L V., Pinto CA., Franceschini S do CC., Alfenas R de CG. Insufficient iodine intake in pregnant women in different regions of the world: a systematic review. Arch Endocrinol Metab 2019;63(3):306–11. DOI: https://doi.org/10.20945/2359-3997000000151.
Teixeira D., Calhau C., Pestana D., Vicente L., Graça P. Iodo: a importância para a saúde e o papel da alimentação. Programa Nacional Para a Promoção Da Alimentação Saudável. Available at: http://ccipd.pt/wp-content/uploads/newsletter/15-12-11/Iodo_saude_alimentacao_DGS_2014.pdf. Accessed June 22, 2021.
Hynes K., Seal J., Otahal P., Oddy W., Burgess J. Women Remain at Risk of Iodine Deficiency during Pregnancy: The Importance of Iodine Supplementation before Conception and Throughout Gestation. Nutrients 2019;11(1):172. DOI: https://doi.org/10.3390/nu11010172.
Levie D., Korevaar TIM., Bath SC., et al. Association of Maternal Iodine Status With Child IQ: A Meta-Analysis of Individual Participant Data. J Clin Endocrinol Metab 2019;104(12):5957–67. DOI: https://doi.org/10.1210/jc.2018-02559.
Campos R de O., Barreto I dos S., Maia LR de J., et al. Iodine nutritional status in Brazil: a meta-analysis of all studies performed in the country pinpoints to an insufficient evaluation and heterogeneity. Arch Endocrinol Metab 2015;59(1):13–22. DOI: https://doi.org/10.1590/2359-3997000000004.
Rochau U., Qerimi Rushaj V., Schaffner M., et al. Decision-Analytic Modeling Studies in Prevention and Treatment of Iodine Deficiency and Thyroid Disorders: A Systematic Overview. Thyroid 2020;30(5):746–58. DOI: https://doi.org/10.1089/thy.2018.0776.
Munn Z., Moola S., Lisy K., Riitano D., Tufanaru C. Methodological guidance for systematic reviews of observational epidemiological studies reporting prevalence and cumulative incidence data. Int J Evid Based Healthc 2015;13(3):147–53. DOI: https://doi.org/10.1097/XEB.0000000000000054.
Stroup DF., Berlin JA., Morton SC., et al. Meta-analysis of observational studies in epidemiology: a proposal for reporting. Meta-analysis Of Observational Studies in Epidemiology (MOOSE) group. JAMA 2000;283(15):2008–12. DOI: https://doi.org/10.1001/jama.283.15.2008.
Lizarondo L., Stern C., Carrier J., et al. Chapter 8: Mixed methods systematic reviews. Aromataris E, Munn Z (Editors). Joanna Briggs Institute Reviewer’s Manual. The Joanna Briggs Institute; 2017.
Munn Z., Moola S., Lisy K., Riitano D., Tufanaru C. Chapter 5: Systematic reviews of prevalence and incidence. Aromataris E, Munn Z (Editors). Joanna Briggs Institute Reviewer’s Manual. The Joanna Briggs Institute; 2017.
Lucchetta R. Protocol: Prevalence of micronutrient deficiencies in women of childbearing age in Brazil: systematic review and meta-analysis. OSF. DOI: https://doi.org/10.17605/OSF.IO/J9QMH.
Hane PJ. Newsbreaks: Elsevier announces Scopus service. Inf Today 2004. Available at: http://www.infotoday.com/newsbreaks/nb040315-1.shtml. Accessed September 13, 2017.
WHO. Urinary iodine concentrations for determining iodine status in populations. Available at: https://apps.who.int/iris/bitstream/handle/10665/85972/WHO_NMH_NHD_EPG_13.1_eng.pdf.
Team RC. R: A language and environment for statistical computing. n.d.
Wickham H., Hester J., François R. Readr: Read rectangular tet data. R package version 1.1.1. Available at: https://cran.r-project.org/package=readr.
Schwarzer G. Meta: An R package for meta-analysis. R News 2007;7(3):40–5.
Mahadev S., Laszkowska M., Sundström J., et al. Prevalence of Celiac Disease in Patients With Iron Deficiency Anemia—A Systematic Review With Meta-analysis. Gastroenterology 2018;155(2):374-382.e1. DOI: https://doi.org/10.1053/j.gastro.2018.04.016.
Migliavaca CB., Stein C., Colpani V., Munn Z., Falavigna M. Quality assessment of prevalence studies: a systematic review. J Clin Epidemiol 2020;127:59–68. DOI: https://doi.org/10.1016/j.jclinepi.2020.06.039.
Silva de Morais N., Ayres Saraiva D., Corcino C., et al. Consequences of Iodine Deficiency and Excess in Pregnancy and Neonatal Outcomes: A Prospective Cohort Study in Rio de Janeiro, Brazil. Thyroid 2020:thy.2019.0462. DOI: https://doi.org/10.1089/thy.2019.0462.
Corcino CM., Berbara TMBL., Saraiva DA., et al. Variation of iodine status during pregnancy and its associations with thyroid function in women from Rio de Janeiro, Brazil. Public Health Nutr 2019:1–9. DOI: https://doi.org/10.1017/S1368980019000399.
de Souza LSL., Campos R de O., Alves V dos S., et al. Hypertension and Salt-Restrictive Diet Promotes Low Urinary Iodine Concentration in High-Risk Pregnant Women: Results from a Cross-Sectional Study Conducted After Salt Iodination Reduction in Brazil. Biol Trace Elem Res 2020;197(2):445–53. DOI: https://doi.org/10.1007/s12011-020-02028-8.
Saraiva DA., Morais NA de O e S de., Martins Corcino C., et al. Iodine status of pregnant women from a coastal Brazilian state after the reduction in recommended iodine concentration in table salt according to governmental requirements. Nutrition 2018;53:109–14. DOI: https://doi.org/10.1016/j.nut.2018.02.001.
Mioto VCB., Monteiro AC de CNG., de Camargo RYA., et al. High prevalence of iodine deficiency in pregnant women living in adequate iodine area. Endocr Connect 2018;7(5):762–7. DOI: https://doi.org/10.1530/EC-18-0131.
Ferreira SMS., Navarro AM., Magalhães PKR., Maciel LMZ. Iodine insufficiency in pregnant women from the State of São Paulo. Arq Bras Endocrinol Metabol 2014;58(3):282–7. DOI: https://doi.org/10.1590/0004-2730000002979.
Marino MAZ., Martins LC., Esteves RZ., Kasamatsu TS., Maciel RMB. A iodúria de pacientes portadores de tireopatias autoimunes em Santo andré, SP, é comparável à dos indivíduos normais e estável nos últimos dez anos. Arq Bras Endocrinol Metabol 2009;53(1):55–63. DOI: https://doi.org/10.1590/S0004-27302009000100009.
Soares R., Vanacor R., Manica D., et al. Thyroid volume is associated with family history of thyroid disease in pregnant women with adequate iodine intake: a cross-sectional study in southern Brazil. J Endocrinol Invest 2008;31(7):614–7. DOI: https://doi.org/10.1007/BF03345612.
Nazarpour S., Ramezani Tehrani F., Behboudi-Gandevani S., Bidhendi Yarandi R., Azizi F. Maternal Urinary Iodine Concentration and Pregnancy Outcomes in Euthyroid Pregnant Women: a Systematic Review and Meta-analysis. Biol Trace Elem Res 2020;197(2):411–20. DOI: https://doi.org/10.1007/s12011-019-02020-x.
Weng W., Dong M., Zhang J., Yang J., Zhang B., Zhao X. A PRISMA-compliant systematic review and meta-analysis of the relationship between thyroid disease and different levels of iodine intake in mainland China. Medicine (Baltimore) 2017;96(25):e7279. DOI: https://doi.org/10.1097/MD.0000000000007279.
Nazeri P., Kabir A., Dalili H., Mirmiran P., Azizi F. Breast-Milk Iodine Concentrations and Iodine Levels of Infants According to the Iodine Status of the Country of Residence: A Systematic Review and Meta-Analysis. Thyroid 2018;28(1):124–38. DOI: https://doi.org/10.1089/thy.2017.0403.
Nazeri P., Mirmiran P., Kabir A., Azizi F. Neonatal thyrotropin concentration and iodine nutrition status of mothers: a systematic review and meta-analysis. Am J Clin Nutr 2016;104(6):1628–38. DOI: https://doi.org/10.3945/ajcn.116.131953.
Nazeri P., Shab-Bidar S., Pearce EN., Shariat M. Thyroglobulin Concentration and Maternal Iodine Status During Pregnancy: A Systematic Review and Meta-Analysis. Thyroid 2020;30(5):767–79. DOI: https://doi.org/10.1089/thy.2019.0712.
Dineva M., Fishpool H., Rayman MP., Mendis J., Bath SC. Systematic review and meta-analysis of the effects of iodine supplementation on thyroid function and child neurodevelopment in mildly-to-moderately iodine-deficient pregnant women. Am J Clin Nutr 2020;112(2):389–412. DOI: https://doi.org/10.1093/ajcn/nqaa071.
Taylor PN., Okosieme OE., Dayan CM., Lazarus JH. THERAPY OF ENDOCRINE DISEASE: Impact of iodine supplementation in mild-to-moderate iodine deficiency: systematic review and meta-analysis. Eur J Endocrinol 2014;170(1):R1–15. DOI: https://doi.org/10.1530/EJE-13-0651.
Candido AC., Azevedo FM., Machamba AAL., et al. Implications of iodine deficiency by gestational trimester: A systematic review. Arch Endocrinol Metab 2020:507–13. DOI: https://doi.org/10.20945/2359-3997000000289.
Guyatt GH., Oxman AD., Kunz R., Vist GE., Falck-Ytter Y., Schünemann HJ. What is “quality of evidence” and why is it important to clinicians? BMJ 2008;336(7651):995–8. DOI: https://doi.org/10.1136/bmj.39490.551019.BE.
Glasziou P., Chalmers I., Rawlins M., McCulloch P. When are randomised trials unnecessary? Picking signal from noise. BMJ 2007;334(7589):349–51. DOI: https://doi.org/10.1136/bmj.39070.527986.68.
Ministério da Saúde - Brasil. Portaria no 2.362, de 1o de dezembro de 2005: Reestrutura o Programa Nacional de Prevenção e Controle dos Distúrbios por Deficiência de Iodo - DDI, designado por Pró-Iodo. n.d.
The Krakow Declaration on Iodine: Tasks and Responsibilities for Prevention Programs Targeting Iodine Deficiency Disorders. Eur Thyroid J 2018;7(4):201–4. DOI: https://doi.org/10.1159/000490143.
Phillips DI. Iodine, milk, and the elimination of endemic goitre in Britain: the story of an accidental public health triumph. J Epidemiol Community Heal 1997;51(4):391–3. DOI: https://doi.org/10.1136/jech.51.4.391.
Brasil. Ministério da Saúde. Secretaria de Ciência, Tecnologia I e IE em SD de AF e IE. Relação Nacional de Medicamentos Essenciais - 2020. Brasília: Ministério da Saúde; 2010.
Farebrother J., Zimmermann MB., Andersson M. Excess iodine intake: sources, assessment, and effects on thyroid function. Ann N Y Acad Sci 2019:nyas.14041. DOI: https://doi.org/10.1111/nyas.14041.
Brasil. Ministério da Saúde. Secretaria de Atenção à Saúde. Departamento de Ações Programáticas Estratégicas. Gestação de alto risco: manual técnico. Available at: http://www.as.saude.ms.gov.br/wp-content/uploads/2016/07/Gestação-de-Alto-Risco-Manual-Técnico.pdf. Accessed December 19, 2020.
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