Acta Pædiatrica ISSN 0803-5253
REVIEW ARTICLE
Systematic review of the methodological quality of studies designed to create neonatal anthropometric charts Francesca Giuliani (
[email protected])1, Eric Ohuma2,3, Elena Spada4, Enrico Bertino1, Ayesha S. Al Dhaheri5, Douglas G. Altman3, Agustin Conde-Agudelo6,7, Stephen H. Kennedy2, Jose Villar2, Leila Cheikh Ismail2 1.Neonatal Unit, Dipartimento di Scienze della Sanita Pubblica e Pediatriche, Universita degli Studi di Torino, Torino, Italy 2.Nuffield Department of Obstetrics & Gynaecology and Oxford Maternal & Perinatal Health Institute, Green Templeton College, University of Oxford, Oxford, UK 3.Centre for Statistics in Medicine, Botnar Research Centre, University of Oxford, Oxford, UK 4.Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy 5.Department of Nutrition and Health, College of Food and Agriculture, United Arab Emirates University, Al-Ain, UAE 6.Perinatology Research Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD, USA 7.National Institutes of Health/Department of Health and Human Services, Detroit, MI, USA
Keywords Neonatal anthropometric charts, Newborn head circumference, Newborn length, Newborn weight, Systematic review Correspondence Dr F Giuliani, SCDU Neonatologia, Via Ventimiglia 3 – Torino, Italy. Tel: 00393339075767 | Fax: 00390113135510 | Email:
[email protected] Received 1 October 2014; revised 20 March 2015; accepted 1 July 2015.
ABSTRACT Babies all over the world are assessed at birth using neonatal anthropometric charts as a matter of clinical routine. This systematic review evaluated the methodological quality of studies designed to create neonatal anthropometric charts and to highlight features in the charts that could affect clinical decision-making and comparisons between populations. The variety and quality of available charts could affect how newborns at risk are identified, together with the indications for treatment, especially nutritional interventions. Conclusion: The studies that generated the charts currently recommended for clinical use have major methodological limitations and international and regional comparisons are very difficult.
DOI:10.1111/apa.13112
INTRODUCTION Since Lubchenco et al. (1) and Battaglia and Lubchenco (2) first developed charts for assessing intrauterine growth and neonatal size based on birthweight data, many other similar charts have been published. Using thresholds derived from these charts, neonates are classified as small, appropriate or large for gestational age (GA). Almost all are descriptive, reference charts, which describe the size of neonates at a specific location and time as opposed to prescriptive standards that define optimal size for a healthy population at low risk of foetal growth impairment (3). In most other fields of medicine, screening for disease or ill health based on the degree of associated risk involves using a well-defined threshold for a physiological parameter, such as cholesterol, haemoglobin or glucose levels, against an international standard. However, the assessment of neonatal size does not adhere to this international principle, and clinicians must choose from the numerous charts available, all with different cut-off values. In addition, the studies that generated these charts employ a wide range of study populations and methods for estimating GA, various methodological and statistical strategies were used to construct the charts, and the reliability of the actual anthropometric measurements is questionable (4,5). New charts continue to appear (6,7) and controversy persists about their use (8). To the best of our knowledge, the
underlying studies have not been critically appraised in a systematic manner. Therefore, we aimed to evaluate the methodological quality of studies designed to create neonatal anthropometric charts and to highlight features in those charts that could affect clinical decision-making and comparisons between populations.
METHODS This systematic review of observational studies was conducted and reported following the checklist proposed
Key Notes
©2015 Foundation Acta Pædiatrica. Published by John Wiley & Sons Ltd 2015 104, pp. 987–996
Babies worldwide are assessed at birth using neonatal anthropometric charts as a matter of clinical routine. This systematic review evaluated the methodological quality of studies designed to create neonatal anthropometric charts and highlighted features that could affect clinical decision-making and comparisons between populations. We found major methodological limitations with the studies that created the charts that are currently used and that international and regional comparisons were very difficult.
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by the Meta-analysis Of Observational Studies in Epidemiology (MOOSE) group (9). Literature search We searched Medline, Embase, CINAHL and LILACS from January 1990 to April 2014 and Google Scholar using a combination of MeSH terms related to infants at birth (neonate, newborn, foetal growth, intrauterine growth), anthropometric variables (weight, length, head circumference, body mass index, ponderal index), distribution of the variable (percentile, centile, curve, chart) and gestational age. However, we omitted the keyword velocity to exclude longitudinal foetal growth studies. The 1990 threshold was arbitrarily chosen because most of the advanced methodological and statistical approaches for constructing charts, such as the LMS method (10), were proposed in the early 1990s. The reference lists of the relevant publications identified in the first step of the search were screened to find additional articles. There were no languages restrictions. The literature search was performed independently by two reviewers (FG, ES). Study selection We included observational studies with the primary aim of creating neonatal anthropometric charts. Studies were excluded if (i) the primary aim was not to construct neonatal charts, (ii) the aim was to produce customised charts, as opposed to population charts, because their methodology and clinical purpose are different, or (iii) they re-analysed previously published data. In cases of duplicate publication, we selected the more recent and complete version, if necessary, supplemented by additional information that appeared in the other publication. The full texts of all potentially eligible studies were independently assessed by two authors (FG, ES) to determine inclusion. Disagreements were resolved by consensus or by consultation with a third reviewer (LCI). Quality assessment and data extraction The methodological quality of the included studies was assessed using a modified and adapted version of the criteria used in our previous evaluation of foetal growth charts (11) developed by three of the authors (ES, FG, LCI) in advance of the review. There were three domains: study design, statistical methods and reporting of results (Table 1). We assessed 16 quality criteria in the three domains, with some criteria consisting of more than one item. In total, two of the authors (FG, ES) independently assessed 29 items in each study that was included: 17 relating to study design, eight to statistical methods and four to reporting of results. Each item was scored as low risk of bias (score = one) or high risk (score = zero) of bias. If there was insufficient information available to make a judgement about some items, then they were scored as not evaluable. Discrepancies were resolved through discussion or by consultation with the third reviewer (LCI). Corresponding authors of primary studies were contacted to obtain additional information or unpublished relevant data.
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Data synthesis The total quality score for each study was defined as the percentage of low risk of bias items over all 29 items. Scores for the three individual domains were also computed. The median, interquartile range (IQR) and range were calculated as the summary measure of the distribution of scores. The total quality score was fitted with a general linear model that included, as covariates, some study characteristics that were not part of the scoring system, such as year of publication (1990–1994, 1995–1997, 1998–2000, 2001–2003, 2004–2006, 2007–2009 and 2010–2014), region where the population was recruited, classified according to the United Nations 2011 World Population Prospects, publication language (English vs other languages) and difference between the highest and the lowest gestational age considered (0–10, 11–15, 16–20 and >20 weeks of gestation). All statistical analyses were carried out using SAS 9.2 (SAS Institute Inc, Cary, NC, USA). RESULTS Of the 1199 citations identified, 113 were retrieved for full-text review (Fig. 1) and 105 studies were included in the systematic review (Appendix S1). The main characteristics of the included studies are presented in Table S1. There were 81 (77%) studies published in English, 12 (12%) in Spanish, six (6%) in Italian, four (4%) in French and two (2%) in Portuguese. The sample size ranged from 973 to 9 640 889 (median, 31 577). The majority (61%) of studies were hospital based and 39 (37%) were population based, and the source of data was unclear in the remaining three (3%) studies. The studies were conducted in Europe (31%), Asia (24%), North America (20%), Latin America and the Caribbean (14%), Africa (7%) and Oceania (4%). The great majority (95%) reported birthweight for GA, but neonatal length and head circumference were only reported in 40% and 37% of the studies, respectively. The minimum GA considered in the charts was 20–23 weeks in 30% of the studies, 24–27 weeks in 34% of the studies and 28 weeks or higher in 36% of the studies. Table S2 depicts the assessment of the methodological quality and the total quality score for each included study. The aim was to construct standards in 31 studies. Of these, eight adopted exclusion criteria to select a suitable population. Overall, the quality of these studies was adequate, even though none met all the basic criteria to construct a reliable chart, which were preplanned study, reliable evaluation of GA, acceptable description of measuring instruments and reliability of the measures, and centiles divided by sex. Of the 105 studies, 20 had a total quality score above 50%, with only one above 75% (12). Of these 20 studies, eight aimed to construct a reference, eight aimed to construct a standard and in four the aim was uncertain. Almost all these studies presented charts by sex and all had smoothed centiles. The Z-scores could be derived in 11 studies. Only six of the 20 studies had a total quality score more than 50% and met the
©2015 Foundation Acta Pædiatrica. Published by John Wiley & Sons Ltd 2015 104, pp. 987–996
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Table 1 Methodological quality criteria Domain 1. Study design 1.1 Aim of the study
1.2 Definition of target population
1.3 Distinction between reference and standard 1.4 Sample selection
1.5. Gestational age evaluation
1.6. Anthropometric evaluation
1.7. Number of neonates at each GA
2. Statistical methods 2.1. Assessment of outliers
2.2. Gender as covariate
Low risk of bias
High risk of bias
Rationale
To create neonatal size charts, for weight, length, head circumference, or a combination of weight and length Target population was clearly defined, such as geographical area, ethnic group, single or multiple pregnancy, among others The authors clearly stated whether the chart was a reference or a standard or this information could be discerned from the Methods section The sample was part of the target population, and the inclusion/exclusion criteria were clearly reported. Data were collected prospectively enrolling the neonates consecutively 1.4.1 Study was planned 1.4.2 Enrolment in accordance with criterion 1.2 1.4.3 Enrolment in accordance with criterion 1.3 1.5.1 Gestational age (GA) was determined by both last menstrual period (LMP) and ultrasound assessment (US) 1.5.2 Reliability of the GA was based on the difference between US and LMP assessment (
