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• Ethnic disparity in risk of SIDS and other unexplained infant death is not due to deprivation; examining ethnic patterns may help to clarify aetiology
  Mary E. Kroll, Maria A. Quigley, Jennifer J. Kurinczuk and Jennifer Hollowell
  Published on: 2 October 2018
• Deprivation is the most striking finding of this study; other known risk factors must be explored to explain ethnic variation
  Melissa Bartick, Cecí Tomori
  Published on: 11 September 2018

• Published on: 2 October 2018

  Ethnic disparity in risk of SIDS and other unexplained infant death is not due to deprivation; examining ethnic patterns may help to clarify aetiology

  • Mary E. Kroll, Researcher in Statistics and Epidemiology Policy Research Unit in Maternal Health and Care, National Perinatal Epidemiology Unit, University of Oxford
  • Other Contributors:
    • Maria A. Quigley, Professor of Statistical Epidemiology
    • Jennifer J. Kurinczuk, Professor of Perinatal Epidemiology
    • Jennifer Hollowell, Associate Professor

  We thank Professors Bartick and Tomori for their comments on our paper. [1] We entirely agree that unexplained death in infancy (UDI) in the (mainly White British) general population of England and Wales is strongly associated with deprivation, as shown by many previous studies. Clearly, any factor that is associated with deprivation among the White British group will be a risk factor for UDI in the general population.

  However, our paper is about ethnic, not socio-economic, variation. [2] The finding of a nearly five-fold disparity in risk across ethnic groups in England and Wales is both striking and novel. Moreover, we demonstrate that this disparity is not explained by deprivation. Formal adjustment for deprivation (IMD quintiles) does not even slightly reduce the ethnic variation (see Table 2). A simple scatter plot of ethnic groups illustrates the lack of a relationship between deprivation and risk, with a virtually horizontal overall trend line (see Figure at https://doi.org/10.5287/bodleian:XmE4XBaoZ). For example, Black Caribbean babies have nearly triple the UDI risk of Black African babies, but similar levels of deprivation. The Indian, Pakistani and Bangladeshi ethnic groups each have around half the UDI risk of White British babies; the White British and Indian groups have similar (relatively low) levels of deprivation, and the Pakistani and Bangladeshi groups are the most deprived in England and...

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  We thank Professors Bartick and Tomori for their comments on our paper. [1] We entirely agree that unexplained death in infancy (UDI) in the (mainly White British) general population of England and Wales is strongly associated with deprivation, as shown by many previous studies. Clearly, any factor that is associated with deprivation among the White British group will be a risk factor for UDI in the general population.

  However, our paper is about ethnic, not socio-economic, variation. [2] The finding of a nearly five-fold disparity in risk across ethnic groups in England and Wales is both striking and novel. Moreover, we demonstrate that this disparity is not explained by deprivation. Formal adjustment for deprivation (IMD quintiles) does not even slightly reduce the ethnic variation (see Table 2). A simple scatter plot of ethnic groups illustrates the lack of a relationship between deprivation and risk, with a virtually horizontal overall trend line (see Figure at https://doi.org/10.5287/bodleian:XmE4XBaoZ). For example, Black Caribbean babies have nearly triple the UDI risk of Black African babies, but similar levels of deprivation. The Indian, Pakistani and Bangladeshi ethnic groups each have around half the UDI risk of White British babies; the White British and Indian groups have similar (relatively low) levels of deprivation, and the Pakistani and Bangladeshi groups are the most deprived in England and Wales.

  In the paper we discuss various potential mediators of the ethnic differences, including sleep practices [3] breastfeeding [4,5] and tobacco use [6], based on the ethnic-specific prevalence of these factors in prior survey data. We suggest that careful comparison of ethnic patterns of exposure and outcome might lead to a better understanding of the aetiology of these very distressing deaths.

   

  1. Bartick M, Tomori C. Deprivation is the most striking finding of this study; other known risk factors must be explored to explain ethnic variation. 2018. https://jech.bmj.com/content/early/2018/07/04/jech-2018-210453.responses....
  2. Kroll ME, Quigley MA, Kurinczuk JJ, et al. Ethnic variation in unexplained deaths in infancy, including sudden infant death syndrome (SIDS), England and Wales 2006-2012: national birth cohort study using routine data. J Epidemiol Community Health 2018;72(10):911-18. doi: 10.1136/jech-2018-210453
  3. Farooqi S, Perry IJ, Beevers DG. Ethnic differences in infant-rearing practices and their possible relationship to the incidence of sudden infant death syndrome (SIDS). Paediatr Perinat Epidemiol 1993;7(3):245-52.
  4. Griffiths LJ, Tate AR, Dezateux C. The contribution of parental and community ethnicity to breastfeeding practices: evidence from the Millennium Cohort Study. Int J Epidemiol 2005;34(6):1378-86. doi: 10.1093/ije/dyi162
  5. Griffiths LJ, Tate AR, Dezateux C, et al. Do early infant feeding practices vary by maternal ethnic group? Public Health Nutr 2007;10(9):957-64. doi: 10.1017/S1368980007665513

  6. Wardle H. Use of tobacco products. Health Survey for England 2004: the health of minority ethnic groups: The Information Centre 2006:93-129.

   

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  Conflict of Interest:
  None declared.

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• Published on: 11 September 2018

  Deprivation is the most striking finding of this study; other known risk factors must be explored to explain ethnic variation

  • Melissa Bartick, Assistant Professor of Medicine Cambridge Health Alliance and Harvard Medical School
  • Other Contributors:
    • Cecí Tomori, Assistant Professor of Anthropology

  We read with interest the article by Kroll et al., “Ethnic variation in unexplained death in infancy, including sudden infant death syndrome (SIDS), England and Wales 2006-12: national birth cohort study using routine data”[1]. While the five-fold disparity in death rates across ethnic groups is notable, the most striking finding was marked association of infant death with deprivation seen in Table 1, with an OR of 3.45 (95% CI 2.82-4.23) between the most deprived group and the least deprived group. Indeed, 69% of deaths were found in the two most deprived quintiles. The analytical attention on ethnic variation in the paper overshadows the central finding that the majority of risk is driven by poverty.

  Furthermore, unmarried status is a potent indicator of socioeconomic status that may cluster with poverty, lack of social support and experiences of racial discrimination. The remaining variation that the paper attributes to possible cultural variation must be broken down into specific known risk factors, such as tobacco exposure, sleep position, preterm birth, alcohol and substance abuse, lack of prenatal care, formula feeding, sofa sharing, and the combination of bedsharing with these other risk factors[2].These known risk factors are also largely clustered around poverty. Even sleep position is indirectly associated with poverty via formula feeding, as videographic data show that bedsharing formula feeding infants are more likely to assume hazardous sleep position...

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  We read with interest the article by Kroll et al., “Ethnic variation in unexplained death in infancy, including sudden infant death syndrome (SIDS), England and Wales 2006-12: national birth cohort study using routine data”[1]. While the five-fold disparity in death rates across ethnic groups is notable, the most striking finding was marked association of infant death with deprivation seen in Table 1, with an OR of 3.45 (95% CI 2.82-4.23) between the most deprived group and the least deprived group. Indeed, 69% of deaths were found in the two most deprived quintiles. The analytical attention on ethnic variation in the paper overshadows the central finding that the majority of risk is driven by poverty.

  Furthermore, unmarried status is a potent indicator of socioeconomic status that may cluster with poverty, lack of social support and experiences of racial discrimination. The remaining variation that the paper attributes to possible cultural variation must be broken down into specific known risk factors, such as tobacco exposure, sleep position, preterm birth, alcohol and substance abuse, lack of prenatal care, formula feeding, sofa sharing, and the combination of bedsharing with these other risk factors[2].These known risk factors are also largely clustered around poverty. Even sleep position is indirectly associated with poverty via formula feeding, as videographic data show that bedsharing formula feeding infants are more likely to assume hazardous sleep positions than breastfeeding infants[3], and prone sleep is generally not seen in breastfeeding infants sleeping with their mothers[4].

  While some of the ethnic variation may be driven by genuine cultural traditions, without data on other major known risk factors of SUID associated with poverty, this analysis could lead to a mistaken overemphasis on ethnicity.

  1 Kroll ME, Quigley MA, Kurinczuk JJ, et al. Ethnic variation in unexplained deaths in infancy, including sudden infant death syndrome (SIDS), England and Wales 2006-2012: national birth cohort study using routine data. J Epidemiol Community Health 2018.
  2 Bartick M, Tomori C. Sudden infant death and social justice: A syndemics approach. Matern Child Nutr 2018 Aug 23:e12652.{Epub ahead of print].
  3 Ball HL. Parent-infant bed-sharing behavior : Effects of feeding type and presence of father. Hum Nat 2006;17:301-18.
  4 Richard C, Mosko S, McKenna J, et al. Sleeping position, orientation, and proximity in bedsharing infants and mothers. Sleep 1996;19:685-90.

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  Conflict of Interest:
  None declared.

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