2nd June 2017, Volume 130 Number 1456

Edwin A Mitchell, John MD Thompson, Jane Zuccollo, Melanie MacFarlane, Barry Taylor, Dawn Elder, Alistair W Stewart, Teuila Percival, Nick Baker, Gabrielle McDonald, Beverley Lawton, Martin Schlaud, Peter Fleming

Abbreviations aOR Adjusted odds ratio CI Confidence interval NIIO National Initial Investigation Office OR Odds ratio PAR Population attributable risk PMMRC Perinatal and Maternal Mortality Review Committee SIDS Sudden infant…

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Summary

This study has shown that many of the risk factors that were identified in the original New Zealand Cot Death Study (1987–1989) are still relevant today. The combination of maternal smoking in pregnancy and bed sharing is extremely hazardous for infants. Furthermore, our findings indicate that the SUDI prevention messages are still applicable today and should be reinforced. SUDI mortality could be reduced to just 7 p.a. in New Zealand (approximately one in 10,000 live births).

Abstract

Despite a major reduction in overall infant mortality, sudden unexpected death in infancy (SUDI) continues to be of concern in New Zealand, as the rate is high by international standards, and is even higher in indigenous Māori.

Aim

To identify modifiable risk factors for SUDI.

Method

A three-year (1 March 2012–28 February 2015) nationwide case-control study was conducted in New Zealand.

Results

There were 137 SUDI cases, giving a SUDI mortality rate of 0.76/1,000 live births. The rate for Māori was 1.41/1,000, Pacific 1.01/1,000 and non-Māori non-Pacific (predominantly European) 0.50/1,000. The parent(s) of 97% of the SUDI cases were interviewed. Six hundred and forty-nine controls were selected and 258 (40%) were interviewed. The two major risk factors for SUDI were: maternal smoking in pregnancy (adjusted OR=6.01, 95% CI=2.97, 12.15) and bed sharing (aOR=4.96, 95% CI=2.55, 9.64). There was a significant interaction (p=0.002) between bed sharing and antenatal maternal smoking. Infants exposed to both risk factors had a markedly increased risk of SUDI (aOR=32.8, 95% CI=11.2, 95.8) compared with infants not exposed to either risk factor. Infants not sharing the parental bedroom were also at increased risk of SUDI (aOR=2.77, 95% CI=1.45, 5.30). Just 21 cases over the three-year study were not exposed to smoking in pregnancy, bed sharing or front or side sleeping position.

Conclusion

This study has shown that many of the risk factors that were identified in the original New Zealand Cot Death Study (1987–1989) are still relevant today. The combination of maternal smoking in pregnancy and bed sharing is extremely hazardous for infants. Furthermore, our findings indicate that the SUDI prevention messages are still applicable today and should be reinforced. SUDI mortality could be reduced to just seven p.a. in New Zealand (approximately one in 10,000 live births).

Author Information

Edwin A Mitchell, Professorial Research Fellow, Department of Paediatrics: Child and Youth Health, University of Auckland, Auckland; John MD Thompson, Epidemiologist/Statistician, Department of Paediatrics: Child and Youth Health, University of Auckland, Auckland; Jane Zuccollo, Perinatal Pathologist, Department of Obstetrics and Gynaecology, University of Otago, Wellington; Melanie MacFarlane, Project Manager, Communio, Auckland; Barry Taylor, Dean, Department of the Dean, Dunedin School of Medicine, University of Otago, Dunedin; Dawn Elder, Professor and HOD, Department of Paediatrics and Child Health, University of Otago, Wellington; Alistair W Stewart, Biostatistician, Section of Epidemiology & Biostatistics, School of Population Health, University of Auckland, Auckland; Teuila Percival, Senior Lecturer, Pacific Health Section, School of Population Health, University of Auckland, Auckland; Nick Baker, Paediatrician, Nelson Hospital, Nelson; Gabrielle K McDonald, Senior Lecturer, Department of Women’s and Children’s Health, Dunedin School of Medicine, University of Otago, Dunedin; Bev Lawton, Senior Research Fellow, Department of Obstetrics and Gynaecology: Women’s Health Research Centre, University of Otago, Wellington; Martin Schlaud, Professor of Epidemiology, Department of Epidemiology and Health Monitoring, Robert Koch Institute, Berlin, Germany; Peter Fleming, Professor of Infant Health and Developmental Physiology, School of Social and Community Medicine, University of Bristol, Bristol, England.

Acknowledgements

We thank the Health Research Council of New Zealand for funding the feasibility study and this study, Cure Kids for their support of EAM and JMDT, and Communio who managed the project. We also thank Yvonne Ledesma-Allard, Lead Medicolegal Investigator, Miami-Dade Medical Examiner, Miami, Florida who trained the SUDI Liaison staff in conducting scene investigations. 
A steering group met monthly by teleconference. This comprised: Professor Ed Mitchell (Principal investigator and Chair), Chief Coroner Neil MacLean, Ms Jackie Andrews (Office of the Chief Coroner), Coroner Morag McDowell, Mr Glenn Dobson (Charlotte Davies) (Operations Manager, Coronial Services), Mr Dave Aro (Director, Communio), Ms Melanie MacFarlane (project manager), Professor Dawn Elder (co-investigator), Dr Nick Baker (co-investigator and chair of the Child and Youth Mortality Review Committee), Associate Professor Beverley Lawton (Māori adviser), Dr Jane Vuletic and Dr Jane Zuccollo (pathologists), Inspector Patricia O’Shaughnessy (NZ Police).
We thank the SUDI Liaison staff who conducted the interviews: Shelley Jonas, Elaine McLardy, Genevieve Ali, Jazz Heer, Tracy Rewiri, Rebecca Passi and Judy McIntyre.
Finally, we especially thank the families of both bereaved and control infants for participating in this study, which would not have been possible without their willingness to share their stories with us.

Correspondence

Professor Ed Mitchell, Department of Paediatrics: Child and Youth Health, University of Auckland, Private Bag 92019, Auckland 1142.

Correspondence Email

e.mitchell@auckland.ac.nz

Competing Interests

Nil.

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