An evaluation of pathologists’ application of the diagnostic criteria from the San Diego definition of SIDS and unclassified sudden infant death

  • Rebecca A. ShipstoneEmail author
  • Jeanine Young
  • John M. D. Thompson
  • Roger W. Byard
Original Article


Despite being widely used, few studies have assessed the utility of the San Diego definition of sudden infant death syndrome (SIDS). The purpose of this study was to evaluate pathologists’ application of the San Diego definition in all cases of sudden unexpected death in infancy (SUDI) that occurred in Queensland, Australia, between 2010 and 2014. Key coronial documents of 228 cases of SUDI were reviewed independently by three reviewers and classified according to the San Diego definition. Clear guidance regarding the evidentiary threshold for classification and interpretation of the San Diego definition was provided. All reviewers classified cases identically in 202 cases (88.6%). Consensus was achieved on the classification of the remaining 26 deaths following case discussion. After review, 79 cases were classified as SIDS, a one third reduction compared with the original classification, mainly due to a high probability of accidental asphyxia. The number of cases classified as undetermined (USID) almost doubled (75/228, 32.9%), and there was more than a fivefold increase in cases classified as asphyxia (43/228, 18.9%). Natural conditions decreased by approximately one third (21/228, 9.2%). This study demonstrates that with clear guidelines for interpretation, the San Diego definition can be applied reliably, with discrepancies resolved through a process of peer review.


Sudden infant death syndrome (SIDS) Sudden unexpected deaths in infancy (SUDI) Asphyxia Diagnosis Classification Standard of proof 


Data accessibility statement

The datasets used and/or analysed during the current study are not available publicly as these were not specified in the original ethical approval request, however may be available in part from the corresponding author on reasonable request.

Compliance with ethical standards

This data used in this study was obtained with the ethical approval of the University of the Sunshine Coast Human Research Ethics Committee (HREC: S/15/805), in accordance with the 1964 Declaration of Helsinki (and its later amendments) and national laws. Due to the retrospective nature of the study, ethical approval included a waiver of the requirement for participant consent to use their information. Permission to access coronial documents was granted under Part 3 Section 53 of the Coroners Act 2003.

Conflict of interest

The authors declare that they have no conflict of interest.


  1. 1.
    Garstang J, Griffiths F, Sidebotham P (2014) What do bereaved parents want from professionals after the sudden death of their child: a systematic review of the literature. BMC Pediatr 14:269. CrossRefPubMedPubMedCentralGoogle Scholar
  2. 2.
    Byard RW (2001) Inaccurate classification of infant deaths in Australia: a persistent and pervasive problem. Med J Aust 175(1):5–7PubMedGoogle Scholar
  3. 3.
    Hunt C, Darnall R, McEntire B, Hyma B (2015) Assigning cause for sudden unexpected infant death. Forensic Sci Med Pathol 11(2):283–288. CrossRefPubMedPubMedCentralGoogle Scholar
  4. 4.
    Krous HF, Beckwith JB, Byard RW, Rognum TO, Bajanowski T, Corey T, Cutz E, Hanzlick R, Keens TG, Mitchell EA (2004) Sudden infant death syndrome and unclassified sudden infant deaths: a definitional and diagnostic approach. Pediatrics 114(1):234–238CrossRefGoogle Scholar
  5. 5.
    Mitchell EA, Krous HF (2015) Sudden unexpected death in infancy: a historical perspective. J Paediatr Child Health 51(1):108–112. CrossRefPubMedGoogle Scholar
  6. 6.
    Jensen LL, Rohde MC, Banner J, Byard RW (2012) Reclassification of SIDS cases - a need for adjustment of the San Diego classification? Int J Legal Med 126(2):271–277. CrossRefPubMedGoogle Scholar
  7. 7.
    Blair PS, Byard RW, Fleming PJ (2012) Sudden unexpected death in infancy (SUDI): suggested classification and applications to facilitate research activity. Forensic Sci Med Pathol 8(3):312–315. CrossRefPubMedGoogle Scholar
  8. 8.
    Blair PS, Byard RW, Fleming PJ (2009) Proposal for an international classification of SUDI. Scand J Forens Sci 15:6–9Google Scholar
  9. 9.
    Sidebotham P, Bajanowski T, Keens T, Kenner T, Kerbl R, Kurz R, Mitchell EA, Moon R, Taylor B, Vennemann M (2010) Proposal for an International Classification of SUDI: a response to Blair, Byard and Fleming. Scand J Forens Sci 16(1):9–11Google Scholar
  10. 10.
    Shapiro-Mendoza CK, Parks SE, Brustrom J, Andrew T, Camperlengo L, Fudenberg J, Payn B, Rhoda D (2017) Variations in cause-of-death determination for sudden unexpected infant deaths. Pediatrics 140(1):e20170087. CrossRefPubMedPubMedCentralGoogle Scholar
  11. 11.
    Byard RW, Shipstone RA, Young J (2019) Continuing major inconsistencies in the classification of unexpected infant deaths. J Forensic Legal Med 64:20–22. CrossRefGoogle Scholar
  12. 12.
    Kennare R, Scheil W, Tucker G (2015) A public health approach to review of sudden unexpected infant deaths-challenges and interventions. Australian Journal of Child and Family Health Nursing 12(1):9–14Google Scholar
  13. 13.
    Byard RW, Marshall D (2007) An audit of the use of definitions of sudden infant death syndrome (SIDS). J Forensic Legal Med 14(8):453–455. CrossRefGoogle Scholar
  14. 14.
    Fleming PJ, Blair PS, Pease A (2015) Sudden unexpected death in infancy: aetiology, pathophysiology, epidemiology and prevention in 2015. Arch Dis Child 100:984–988. CrossRefPubMedGoogle Scholar
  15. 15.
    Camperlengo LT, Shapiro-Mendoza CK, Kim SY (2012) Sudden infant death syndrome: diagnostic practices and investigative policies, 2004. Am J Forensic Med Pathol 33(3):197–201CrossRefGoogle Scholar
  16. 16.
    Gould SJ, Weber MA, Sebire NJ (2010) Variation and uncertainties in the classification of sudden unexpected infant deaths among paediatric pathologists in the UK: findings of a National Delphi Study. J Clin Pathol 63(9):796–799. CrossRefPubMedGoogle Scholar
  17. 17.
    Shapiro-Mendoza CK, Tomashek KM, Anderson RN, Wingo J (2006) Recent national trends in sudden, unexpected infant deaths: more evidence supporting a change in classification or reporting. Am J Epidemiol 163(8):762–769CrossRefGoogle Scholar
  18. 18.
    Malloy MH, MacDorman M (2005) Changes in the classification of sudden unexpected infant deaths: United States, 1992–2001. Pediatrics 115(5):1247–1253. CrossRefPubMedGoogle Scholar
  19. 19.
    Hunt CE, Hauck FR (2006) Sudden infant death syndrome. CMAJ 174(13):1861–1869. CrossRefPubMedPubMedCentralGoogle Scholar
  20. 20.
    Mitchell EA (2015) Co-sleeping and suffocation. Forensic Sci Med Pathol 11(2):277–278CrossRefGoogle Scholar
  21. 21.
    Taylor BJ, Garstang J, Engelberts A, Obonai T, Cote A, Freemantle J, Vennemann M, Healey M, Sidebotham P, Mitchell EA, Moon RY (2015) International comparison of sudden unexpected death in infancy rates using a newly proposed set of cause-of-death codes. Arch Dis Child 100(11):1018–1023. CrossRefPubMedGoogle Scholar
  22. 22.
    Randall B, Donelan K, Koponen M, Sens MA, Krous HF (2012) Application of a classification system focusing on potential asphyxia for cases of sudden unexpected infant death. Forensic Sci Med Pathol 8(1):34–39CrossRefGoogle Scholar
  23. 23.
    Moon RY, Byard RW (2014) Need for a working classification system for sudden and unexpected infant deaths. Pediatrics 134(1):e240–e241. CrossRefPubMedGoogle Scholar
  24. 24.
    Möllborg P (2019) Differences between infants sleeping alone or with others provides clues to preventing sudden unexpected deaths due to accidental suffocation. Acta Paediatr 108(4):586–587. CrossRefPubMedGoogle Scholar
  25. 25.
    Schnitzer PG, Covington TM, Dykstra HK (2012) Sudden unexpected infant deaths: sleep environment and circumstances. Am J Public Health 102(6):1204–1212. CrossRefPubMedPubMedCentralGoogle Scholar
  26. 26.
    Byard RW, Beal SM (1995) Has changing diagnostic preference been responsible for the recent fall in incidence of sudden infant death syndrome in South Australia? J Paediatr Child Health 31(3):197–199CrossRefGoogle Scholar
  27. 27.
    Pasquale-Styles MA, Tackitt PL, Schmidt CJ (2007) Infant death scene investigation and the assessment of potential risk factors for asphyxia: a review of 209 sudden unexpected infant deaths. J Forensic Sci 52(4):924–929. CrossRefPubMedGoogle Scholar
  28. 28.
    Byard RW (2015) Overlaying, co-sleeping, suffocation, and sudden infant death syndrome: the elephant in the room. Forensic Sci Med Pathol 11(2):273–274CrossRefGoogle Scholar
  29. 29.
    Hayman RM, McDonald G, Baker NJ, Mitchell EA, Dalziel SR (2015) Infant suffocation in place of sleep: New Zealand national data 2002–2009. Arch Dis Child 100(7):610–614. CrossRefPubMedGoogle Scholar
  30. 30.
    Randall BB, Wadee SA, Sens MA, Kinney HC, Folkerth RD, Odendaal HJ, Dempers JJ (2009) A practical classification schema incorporating consideration of possible asphyxia in cases of sudden unexpected infant death. Forensic Sci Med Pathol 5(4):254–260. CrossRefPubMedPubMedCentralGoogle Scholar
  31. 31.
    Shapiro-Mendoza CK, Camperlengo L, Ludvigsen R, Cottengim C, Anderson RN, Andrew T, Covington T, Hauck FR, Kemp J, MacDorman M (2014) Classification system for the Sudden Unexpected Infant Death Case Registry and its application. Pediatrics 134(1):e210–e219. CrossRefPubMedPubMedCentralGoogle Scholar
  32. 32.
    Bajanowski T, Brinkmann B, Vennemann M (2006) The San Diego definition of SIDS: practical application and comparison with the GeSID classification. Int J Legal Med 120(6):331–336CrossRefGoogle Scholar
  33. 33.
    Queensland Police (2019) Operational procedures manual. Public Edition, January 2019 edn. Queenland Police BrisbaneGoogle Scholar
  34. 34.
    The State of Queensland (Queenlsand State Coroner) (2013) State coroner’s guidelines. Queensland Courts. Accessed 26 April 2019
  35. 35.
    Mitchell EA, Thompson JM, Zuccollo J, MacFarlane M, Taylor B, Elder D, Stewart AW, Percival T, Baker N, McDonald GK, Lawton B, Schlaud M, Fleming PJ (2017) The combination of bed sharing and maternal smoking leads to a greatly increased risk of sudden unexpected death in infancy: the New Zealand SUDI Nationwide Case Control Study. N Z Med J 130(1456):52–64PubMedGoogle Scholar
  36. 36.
    New South Wales Child Death Review Team (2005) Sudden unexpected deaths in infancy: the New South Wales experience. New South Wales Commission for Children and Young People, SydneyGoogle Scholar
  37. 37.
    Tonkin S, Coroner (2009) Inquest into the death of Brendan Scott Kay. Coroner’s Court Townsville. Available via Accessed 18 May 2019
  38. 38.
    Byard RW (2009) SUDI or “undetermined”: does it matter? Forensic Sci Med Pathol 5(4):252–253. CrossRefPubMedGoogle Scholar
  39. 39.
    Becroft DM (2003) An international perspective. Arch Pediatr Adolesc Med 157(3):292–292CrossRefGoogle Scholar
  40. 40.
    Blackwell C, Brouillette B, Byard RW, Jeffrey H, Mundine K (2001) Where to from here? – panel discussion. Paper presented at the Child and Infant Mortality Matters, SIDS Australia National Meeting, Canberra, Australia, March 2001Google Scholar
  41. 41.
    Byard RW, Jensen LL (2007) Fatal asphyxial episodes in the very young: classification and diagnostic issues. Forensic Sci Med Pathol 3(3):177–181CrossRefGoogle Scholar
  42. 42.
    Byard RW, Tsokos M (2005) Infant and early childhood asphyxial deaths - diagnostic issues. In: Tsokos M, Totowa NJ (eds) Forensic pathology reviews, vol 2. Humana Press.
  43. 43.
    Carpenter B, Tait G (2010) The autopsy imperative: medicine, law, and the coronial investigation. J Med Humanit 31(3):205–221. CrossRefPubMedGoogle Scholar
  44. 44.
    Lambert ABE, Parks SE, Cottengim C, Faulkner M, Hauck FR, Shapiro-Mendoza CK (2019) Sleep-related infant suffocation deaths attributable to soft bedding, overlay, and wedging. Pediatrics 143(5):e20183408CrossRefGoogle Scholar

Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.School of Nursing, Midwifery, and ParamedicineUniversity of the Sunshine CoastSippy DownsAustralia
  2. 2.Departments of Paediatrics, Child and Youth Health, and Obstetrics and Gynaecology, Faculty of Medical and Health ScienceUniversity of AucklandAucklandNew Zealand
  3. 3.Forensic Science South Australia (FSSA) and the School of MedicineThe University of AdelaideAdelaideAustralia

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