Abstract
Objectives: To determine the impact of neighbourhood income and maternal residence population density on mortality and various morbidities at discharge or transfer from the NICU among extremely preterm neonates (<27 weeks gestation) in Canada.
Methods: Neighbourhood income level and residential status was derived using a postal code conversion file and census data. Multivariable logistic regression analysis was used to estimate the risk-adjusted odds ratio (AOR) of mortality and survival without major morbidities (chronic lung disease, necrotizing enterocolitis, severe intraventricular hemorrhage, and retinopathy of prematurity) among 2,752 extremely preterm infants admitted to 25 tertiary level neonatal intensive care units in Canada between 2007 and 2008.
Results: There were no significant differences between mothers from different neighbourhood income quintiles (Q1 = low; Q5 = high) and neonatal mortality AOR (95% confidence interval): Q1: 1.10 (0.74–1.62), Q2: 1.00 (0.67–1.49), Q3: 1.39 (0.93–2.07), Q4: 1.01 (0.67–1.52), Q5: 1 (reference); or survival without major morbidity: Q1: 1.01 (0.70–1.44), Q2: 0.84 (0.58-–1.23), Q3: 0.85 (0.58–1.24), Q4: 0.92 (0.63–1.35), Q5: 1 (reference). There were no significant differences in mortality (AOR 1.14 [0.83–1.57]) or in survival without major morbidity (AOR 0.92 [0.67–1.26]) between infants of mothers residing in sparsely populated areas compared to densely populated areas.
Conclusion: Maternal residence in a low-income neighbourhood or sparsely populated area was not associated with higher odds of mortality or survival free of major morbidities in extremely preterm infants.
Key words: Neonatal mortality, morbidity, preterm birth, neonatal intensive care unit, socioeconomic status
Résumé
Objectifs: Déterminer l’impact du revenu du quartier et de la densité de population du lieu de résidence maternel sur la mortalité et sur diverses morbidités lors du congé ou du transfert des unités néonatales de soins intensifs chez les grands prématurés (<27 semaines de gestation) au Canada.
Méthode: Le niveau de revenu du quartier et le statut résidentiel ont été dérivés à l’aide d’un fichier de conversion du code postal et des données du Recensement. Au moyen d’une analyse de régression logistique multivariée, nous avons estimé le rapport de cotes ajusté selon le risque (RCa) pour la mortalité et pour la survie sans morbidité grave (pneumopathie chronique, entérocolite nécrosante néonatale, hémorragie intraventriculaire grave, rétinopathie des prématurés) chez 2 752 grands prématurés hospitalisés dans 25 unités de soins néonatals intensifs de niveau tertiaire au Canada entre 2007 et 2008.
Résultats: Nous n’avons constaté aucun écart significatif entre les mères de différents quintiles de revenu du quartier (Q1=faible; Q5=élevé) dans la mortalité néonatale (intervalle de confiance de 95 %): Q1: 1,10 (0,74–1,62), Q2: 1,00 (0,67–1,49), Q3: 1,39 (0,93–2,07), Q4: 1,01 (0,67–1,52), Q5: 1 (référence), ni dans la survie sans morbidité grave: Q1: 1,01 (0,70–1,44), Q2: 0,84 (0,58–1,23), Q3: 0,85 (0,58–1,24), Q4: 0,92 (0,63–1,35), Q5: 1 (référence). Nous n’avons constaté aucun écart significatif non plus dans la mortalité (RCa 1,14 [0,83–1,57]) ou dans la survie sans morbidité grave (RCa 0,92 [0,67–1,26]) entre les nourrissons de mères habitant des zones à faible densité de population comparativement aux zones urbaines.
Conclusion: La résidence maternelle dans un quartier à faible revenu ou à faible densité de population n’était pas associée à une probabilité plus élevée de mortalité ou de survie sans morbidité grave chez les grands prématurés.
Mots clés: mortalité néonatale, morbidité, naissance prématurée, unité soins intensifs nouveau-né, statut socioéconomique
Footnotes
Site Investigators of the Canadian Neonatal Network: Shoo K. Lee (Director, Canadian Neonatal Network); Prakesh Shah (Associate Director, Canadian Neonatal Network and Site Investigator Mount Sinai Hospital); Wayne Andrews (Janeway Children’s Health and Rehabilitation Centre, St. John’s, NL); Keith Barrington (Sainte Justine Hospital, Montreal, QC); Wendy Yee (Foothills Medical Centre, Calgary, AB); Barbara Bulleid (Everett Chalmers Hospital, Fredericton, NB); Rody Canning (Moncton Hospital, Moncton, NB); Ruben Alvaro (St. Boniface General Hospital, Winnipeg, MB); Kimberly Dow (Kingston General Hospital, Kingston, ON); Michael Dunn (Sunnybrook Health Sciences Centre, Toronto, ON); Adele Harrison (Victoria General Hospital, Victoria, BC); Andrew James (The Hospital for Sick Children, Toronto, ON); Zarin Kalapesi (Regina General Hospital, Regina, SK); Lajos Kovacs (Jewish General Hospital, Montreal, QC); Orlando da Silva (St. Joseph’s Health Centre, London, ON); Douglas McMillan (IWK Health Centre, Halifax, NS); Cecil Ojah (Saint John Regional Hospital, Saint John, NB); Abraham Peliowski/Khalid Aziz (Royal Alexandra Hospital, Edmonton, AB); Bruno Piedboeuf (Centre hospitalier universitaire de Québec, Sainte Foy, QC); Patricia Riley (Montreal Children’s Hospital, Montreal, QC); Daniel Faucher (Royal Victoria Hospital, Montreal, QC); Nicole Rouvinez-Bouali (Children’s Hospital of Eastern Ontario, Ottawa, ON); Koravangattu Sankaran (Royal University Hospital, Saskatoon, SK); Mary Seshia (Health Sciences Centre, Winnipeg, MB); Sandesh Shivananda (Hamilton Health Sciences Centre, Hamilton, ON); Zenon Cieslak (Royal Columbian Hospital, New Westminster, BC); Anne Synnes (Children’s and Women’s Health Centre of British Columbia, Vancouver, BC); Herve Walti (Centre Hospitalier Universitaire de Sherbrooke, Fleurimont, QC).
Conflict of Interest: None to declare.
References
- 1.Frohlich KL, Ross N, Richmond C. Health disparities in Canada today: Some evidence and a theoretical framework. Health Policy. 2006;79(2-3):132–43. doi: 10.1016/j.healthpol.2005.12.010. [DOI] [PubMed] [Google Scholar]
- 2.Demissie K, Rhoads GG, Ananth CV, Alexander GR, Kramer MS, Kogan MD, et al. Trends in preterm birth and neonatal mortality among blacks and whites in the United States from 1989 to 1997. Am J Epidemiol. 2001;1544:307–15. doi: 10.1093/aje/154.4.307. [DOI] [PubMed] [Google Scholar]
- 3.Ahern J, Pickett KE, Selvin S, Abrams B. Preterm birth among African American and white women: A multilevel analysis of socioeconomic characteristics and cigarette smoking. J Epidemiol Community Health. 2003;578:606–11. doi: 10.1136/jech.57.8.606. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Ferguson SE, Smith GN, Salenieks ME, Windrim R, Walker MC. Preterm premature rupture of membranes. Nutritional and socioeconomic factors. Obstet Gynecol. 2002;1006:1250–56. doi: 10.1016/s0029-7844(02)02380-3. [DOI] [PubMed] [Google Scholar]
- 5.Pickett KE, Ahern JE, Selvin S, Abrams B. Neighborhood socioeconomic status, maternal race and preterm delivery: A case-control study. Ann Epidemiol. 2002;126:410–18. doi: 10.1016/S1047-2797(01)00249-6. [DOI] [PubMed] [Google Scholar]
- 6.Robinson JN, Regan JA, Norwitz ER. The epidemiology of preterm labor. Semin Perinatol. 2001;254:204–14. doi: 10.1053/sper.2001.27548. [DOI] [PubMed] [Google Scholar]
- 7.Blumenshine P, Egerter S, Barclay CJ, Cubbin C, Braveman PA. Socioeconomic disparities in adverse birth outcomes: A systematic review. Am J Prev Med. 2010;393:263–72. doi: 10.1016/j.amepre.2010.05.012. [DOI] [PubMed] [Google Scholar]
- 8.Gazmararian JA, Adams MM, Pamuk ER. Associations between measures of socioeconomic status and maternal health behavior. Am J Prev Med. 1996;122:108–15. doi: 10.1016/S0749-3797(18)30353-2. [DOI] [PubMed] [Google Scholar]
- 9.Luo ZC, Kierans WJ, Wilkins R, Liston RM, Mohamed J, Kramer MS. Disparities in birth outcomes by neighborhood income: Temporal trends in rural and urban areas, British Columbia. Epidemiology. 2004;156:679–86. doi: 10.1097/01.ede.0000142149.34095.88. [DOI] [PubMed] [Google Scholar]
- 10.Luo ZC, Wilkins R, Kramer MS. Effect of neighbourhood income and maternal education on birth outcomes: A population-based study. CMAJ. 2006;17410:1415–20. doi: 10.1503/cmaj.051096. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Joseph KS, Liston RM, Dodds L, Dahlgren L, Allen AC. Socioeconomic status and perinatal outcomes in a setting with universal access to essential health care services. CMAJ. 2007;1776:583–90. doi: 10.1503/cmaj.061198. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Luo ZC, Wilkins R, Heaman M, Martens P, Smylie J, Hart L, et al. Birth outcomes and infant mortality by the degree of rural isolation among first nations and non-first nations in Manitoba, Canada. J Rural Health. 2010;262:175–81. doi: 10.1111/j.1748-0361.2010.00279.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13.Luo ZC, Wilkins R. Degree of rural isolation and birth outcomes. Paediatr Perinat Epidemiol. 2008;224:341–49. doi: 10.1111/j.1365-3016.2008.00938.x. [DOI] [PubMed] [Google Scholar]
- 14.Sparks PJ, McLaughlin DK, Stokes CS. Differential neonatal and postneo-natal infant mortality rates across US counties: The role of socioeconomic conditions and rurality. J Rural Health. 2009;254:332–41. doi: 10.1111/j.1748-0361.2009.00241.x. [DOI] [PubMed] [Google Scholar]
- 15.Larson EH, Hart LG, Rosenblatt RA. Is non-metropolitan residence a risk factor for poor birth outcome in the U.S.? Soc Sci Med. 1997;452:171–88. doi: 10.1016/S0277-9536(96)00332-2. [DOI] [PubMed] [Google Scholar]
- 16.Abdel-Latif ME, Bajuk B, Oei J, Vincent T, Sutton L, Lui K. Does rural or urban residence make a difference to neonatal outcome in premature birth? A regional study in Australia. Arch Dis Child Fetal Neonatal Ed. 2006;91(4):F251–F256. doi: 10.1136/adc.2005.090670. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17.Larson EH, Hart LG, Rosenblatt RA. Rural residence and poor birth outcome in Washington state. J Rural Health. 1992;83:162–70. doi: 10.1111/j.1748-0361.1992.tb00348.x. [DOI] [PubMed] [Google Scholar]
- 18.Guildea ZE, Fone DL, Dunstan FD, Cartlidge PH. Differences in risk of mortality under 1 year of age between rural and urban areas: An ecological study. Public Health. 2005;1195:442–47. doi: 10.1016/j.puhe.2004.08.009. [DOI] [PubMed] [Google Scholar]
- 19.Canadian Neonatal Network. Abstractor’s Manual. Toronto, ON: CNN; 2010. [Google Scholar]
- 20.Wilkins R. Health Analysis Division SC. PCCF+ Version 5F User’s Guide: Automated geographic coding based on the Statistics Canada Postal Conversion Files. 2010. [Google Scholar]
- 21.Shennan AT, Dunn MS, Ohlsson A, Lennox K, Hoskins EM. Abnormal pulmonary outcomes in premature infants: Prediction from oxygen requirement in the neonatal period. Pediatrics. 1988;824:527–32. [PubMed] [Google Scholar]
- 22.Papile LA, Burstein J, Burstein R, Koffler H. Incidence and evolution of subependymal and intraventricular hemorrhage: A study of infants with birth weights less than 1,500 gm. J Pediatr. 1978;924:529–34. doi: 10.1016/S0022-3476(78)80282-0. [DOI] [PubMed] [Google Scholar]
- 23.An international classification of retinopathy of prematurity. Pediatrics. 1984;741:127–33. [PubMed] [Google Scholar]
- 24.Bell MJ, Ternberg JL, Feigin RD, Keating JP, Marshall R, Barton L, et al. Neonatal necrotizing enterocolitis. Therapeutic decisions based upon clinical staging. Ann Surg. 1978;1871:1–7. doi: 10.1097/00000658-197801000-00001. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 25.Richardson DK, Corcoran JD, Escobar GJ, Lee SK. SNAP-II and SNAPPE-II: Simplified newborn illness severity and mortality risk scores. J Pediatr. 2001;1381:92–100. doi: 10.1067/mpd.2001.109608. [DOI] [PubMed] [Google Scholar]
- 26.McIntyre E, Hiller JE, Turnbull D. Determinants of infant feeding practices in a low socio-economic area: Identifying environmental barriers to breastfeeding. Aust N Z J Public Health. 1999;232:207–9. doi: 10.1111/j.1467-842X.1999.tb01238.x. [DOI] [PubMed] [Google Scholar]
- 27.McIntyre E, Turnbull D, Hiller JE. Breastfeeding in public places. J Hum Lact. 1999;152:131–35. doi: 10.1177/089033449901500211. [DOI] [PubMed] [Google Scholar]
- 28.Wang LW, Wang ST, Huang CC. Preterm infants of educated mothers have better outcome. Acta Paediatr. 2008;975:568–73. doi: 10.1111/j.1651-2227.2008.00738.x. [DOI] [PubMed] [Google Scholar]
- 29.Luu TM, Vohr BR, Allan W, Schneider KC, Ment LR. Evidence for catch-up in cognition and receptive vocabulary among adolescents born very preterm. Pediatrics. 2011;1282:313–22. doi: 10.1542/peds.2010-2655. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 30.Ghods E, Kreissl A, Brandstetter S, Fuiko R, Widhalm K. Head circumference catch-up growth among preterm very low birth weight infants: Effect on neurodevelopmental outcome. J Perinat Med. 2011;395:579–86. doi: 10.1515/jpm.2011.049. [DOI] [PubMed] [Google Scholar]