Survival disparities in Indigenous and non-Indigenous New Zealanders with colon cancer: the role of patient comorbidity, treatment and health service factors

Sarah Hill (1) , Diana Sarfati (2) , Tony Blakely (2) , Bridget Robson (3) , Gordon Purdie (2) , Jarvis Chen (4) , Elizabeth Dennett (5) , Donna Cormack (3) , Ruth Cunningham (6) , Kevin Dew (7) , Tim Mccreanor (8) , Ichiro Kawachi (4)

1 Edin. - University of Edinburgh
2 Department of Public Health, University of Otago Wellington
3 Te Rôpu Rangahau Hauora a Eru Pômare, University of Otago Wellington
4 Dept of Society, Human Development & Health, Harvard School of Public Health
5 Department of Surgery, University of Otago Wellington
6 Ministry of Health
7 School of Social and Cultural Studies, Victoria University, Wellington
8 Whaariki, Massey University

Background. Ethnic disparities in cancer survival have been documented in many populations and cancer types. The causes of these inequalities are not well understood but may include disease and patient characteristics, treatment differences and health service factors. We compared survival in a cohort of Mâori (Indigenous) and non-Mâori New Zealanders with colon cancer and assessed the contribution of demographics, disease characteristics, patient comorbidity, treatment and health care factors to survival disparities. Methods. Mâori patients diagnosed with colon cancer between 1996 and 2003 were identified from the New Zealand Cancer Registry and compared with a randomly-selected sample of non-Mâori patients. Clinical and outcome data were obtained from medical records, pathology reports and the national mortality database. Cancer-specific survival was examined using Kaplan-Meier survival curves and Cox hazards modelling with multivariable adjustment. Results. We compared 301 Mâori and 328 non-Mâori patients with colon cancer. Mâori had significantly poorer cancer survival than non-Mâori (hazard ratio [HR] = 1.33, 95% CI: 1.03-1.71) that was not explained by demographic or disease characteristics. The most important factors contributing to poorer survival in Mâori were patient comorbidity and markers of health care access, each of which accounted for around a third of the survival disparity. The final model accounted for almost all the survival disparity between Mâori and non-Mâori patients (HR = 1.07, 95% CI: 0.77-1.47). Conclusion. Higher patient comorbidity and poorer access and quality of cancer care are both important explanations for worse survival in Mâori compared with non-Mâori New Zealanders with colon cancer.

Mots clés: CANCER: SURVIVAL; ETHNIC MINORITIES SI; HEALTH SERVICES; INEQUALITIES SI; PUBLIC HEALTH EPIDEMIOLOGY

Sarah Hill, Diana Sarfati, Tony Blakely, Bridget Robson, Gordon Purdie, et al.. Survival disparities in Indigenous and non-Indigenous New Zealanders with colon cancer: the role of patient comorbidity, treatment and health service factors. Journal of Epidemiology and Community Health, 2010, 64 (2), pp.117-n/a. ⟨10.1136/jech.2008.083816⟩. ⟨hal-00499243⟩