Abstract
BackgroundIodine deficiency can adversely affect child development including stunted growth. However, the effect of iodine supplementation or fortification on prenatal and postnatal growth in children (<18 years) is unclear. We identified the potential need for a systematic review to contribute to the evidence base in this area. To avoid duplication and inform the need for a new systematic review and its protocol, we undertook a rapid scoping review of existing systematic reviews investigating the effect of iodised salt and iodine supplements on growth and other iodine-related outcomes.MethodsWe searched TRIP and Epistemokinos (latest search date 15 December 2014). All English language systematic reviews reporting on the effect of iodine supplementation or fortification in any form, dose or regimen on any iodine-related health outcomes (including but not limited to growth) were included. Eligible systematic reviews could include experimental or observational studies in pregnant or lactating women or children to age 18. We tabulated the extracted data to capture the scope of questions addressed, including: author, publication year, most recent search date, participants, pre-specified treatment/exposure and comparator, pre-specified outcomes, outcomes relevant to our question and number and type of studies included. Methodological quality of included reviews was assessed using AMSTAR.ResultsNine hundred and seventy-six records were screened and 10 reviews included. Most studies were of moderate methodological quality. Outcomes included assessments of thyroid function, iodine deficiency disorders, mental development and growth. Populations studied included pregnant women, preterm infants and children into adulthood. Most reviews looked at direct iodine supplementation or fortification, though some reviews considered iodine status, including the relationship between iodine intake and iodine biomarkers. Although five reviews pre-specified inclusion of growth outcomes, none provided synthesised evidence on the effects of iodine supplementation or fortification on prenatal and postnatal somatic growth.ConclusionsOur rapid scoping review demonstrates a gap in the evidence base with no existing, up-to-date systematic reviews on the effects of all forms of iodine supplementation/fortification in all of the relevant population groups on relevant growth and growth-related outcomes. A new systematic review examining this question will assist in addressing this gap.
Highlights
Iodine deficiency has been identified as one of the key preventable factors that can adversely affect child development [1], and is one of the most widespread micronutrient deficiencies worldwide [2]. It can result in a number of developmental and functional abnormalities, the spectrum of which is referred to as the Iodine Deficiency Disorders (IDD) [3, 4]
We formulated the following research question: “What are the effects of iodised salt, iodised oil or iodine supplements compared to placebo or no iodine intervention on prenatal and postnatal somatic growth of the foetus, infant and child?” We identified the potential need for a systematic review to tackle this question
The AMSTAR developers Shea et al [26, 27] state that assessments of publication bias should include a Discussion The objective of this rapid scoping review was to identify the scope, methodological quality and nature of existing systematic reviews that have investigated the effects of iodine supplementation or fortification on prenatal and postnatal growth in children and adolescents
Summary
Iodine deficiency has been identified as one of the key preventable factors that can adversely affect child development [1], and is one of the most widespread micronutrient deficiencies worldwide [2]. It can result in a number of developmental and functional abnormalities, the spectrum of which is referred to as the Iodine Deficiency Disorders (IDD) [3, 4]. It is well established that a deficiency in iodine during the entire pregnancy may cause thyroid dysfunction and have irreversible adverse effects on child development if moderate or severe [7,8,9]. To avoid duplication and inform the need for a new systematic review and its protocol, we undertook a rapid scoping review of existing systematic reviews investigating the effect of iodised salt and iodine supplements on growth and other iodine-related outcomes
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