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Human milk as a protective factor for bronchopulmonary dysplasia: a systematic review and meta-analysis
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  • Published on:
    Impact of human milk on bronchopulmonary dysplasia-Reply
    • Jinglan Huang, Paediatrician Department of Pediatrics, West China Second University Hospital, Sichuan University
    • Other Contributors:
      • Tao Xiong, Paediatrician
      • Dezhi Mu, Paediatrician

    In Reply

    We would like to thank Miller et al for their interest in our recently published review and their responding letter to the editor. The first concern is combining RCTs and cohort studies. We agree that classic Cochrane methods advocate combining only same study designs in a meta-analysis. However, there is also an alternative viewpoint. Appropriate integration of randomized and observational cohort studies may offer opportunities to provide more timely, comprehensive, and generalizable evidence about the medical intervention1. To date, the majority of human milk studies on bronchopulmonary dysplasia (BPD) have been observational cohort studies. Generalizing extensive perspective is motivation for combining randomized and non-randomized evidence in a meta-analysis2. In our review, to detect the possibility of incorporating randomized and observational cohort studies, we assessed the statistic heterogeneity between cohort studies and randomized studies. The test for subgroup differences has been shown in table 3, which demonstrated the statistic heterogeneity (I2 and P values) is generally low. This gave a plausible reason to pool observational and randomized studies in our review. In fact, combining observational and randomized studies has been also performed in a similarly themed review for preventing BPD, when authors compared raw mother’s own milk with pasteurized mother’s own milk3.

    The second concern from Miller et al was how to interpret the out...

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    Conflict of Interest:
    None declared.
  • Published on:
    Impact of human milk on bronchopulmonary dysplasia
    • Jacqueline Miller, Research Fellow South Australian Health and Medical Research Institute
    • Other Contributors:
      • Philippa Middleton, Research Fellow
      • Andrew McPhee, Senior Neonatologist
      • Maria Makrides, Theme leader, Healthy Mothers Babies and Children, SAHMRI
      • Carmel Collins, Principal Research Fellow

    Huang et al recently summarised the role of human milk (HM) in bronchopulmonary dysplasia via a systematic review and meta-analysis of the available evidence. 1 With renewed interest in exclusive HM diets and various HM products now available, it is important for health professionals to have access to quality reviews of the evidence. We would like to make some observations on the Huang article, informed by our recent review. 2
    There were two main differences in inclusion criteria between Huang’s review and ours: Huang et al included infants born <37 weeks’ gestation whereas ours was limited to very low birth weight infants. Huang et al also searched Chinese data-bases for studies in English and Chinese, in addition to conventional databases, partially addressing a limitation of our review which was restricted to studies published in English.
    In their main results, Huang et al have combined RCTs and cohort studies with forest plots showing an overall protective effect of HM. However, in Table 3, in which data are presented by study design, no effect of HM from RCTs is evident. Thus, the overall protective effect is driven by the cohort studies alone. Cochrane methods recommend that different study designs should not be combined in a meta-analysis3 as they can be expected to differ systematically. By not reporting analyses of the different study designs, Huang et al overstate the benefits of HM.
    In our recent meta-analysis 2 of human milk and morbidity...

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    Conflict of Interest:
    None declared.