About the project

One of the challenges facing the New Zealand health system is how to maintain equitable access to a high-performing health system and eliminate existing health inequalities. The C3 project aims to address the role of comorbidity and possible unequal treatment in secondary/tertiary care services among Māori with cancer. Our approach is highly collaborative (actively involving Māori and non-Māori, clinicians, community workers, central and regional health policy and health service delivery professionals) and multidisciplinary. Our focus is on research that informs action with the view to improve equity and quality of care in secondary/ tertiary services for Māori cancer patients.

Aims and objectives

  1. Optimise the measurement of comorbidity in the context of Māori patients with cancer;
  2. Describe the epidemiology of comorbidity among Māori and non-Māori cancer patients in New Zealand including patterns by cancer site, deprivation and region/ rurality;
  3. Establish the associations of each of ethnicity and comorbidity, with completeness and timing of cancer treatments and survival, adjusted for confounding socio-demographics, and stratified by cancer type;
  4. Determine how ethnicity and comorbidity interact in their association with cancer treatment and survival;
  5. Determine how much of the association of ethnicity with cancer survival is mediated by comorbidities, and explore the extent to which this mediation is due to the impact of comorbidity on the timing and completeness of treatment,
  6. Attempt to model what impact there might be upon survival, if all patients received 'best practice' treatment given comorbidities; and
  7. Develop and consider feasibility of interventions based on the findings of the two C3 studies, and on review of relevant sources aimed at improving the adequacy and effectiveness of services for Māori cancer patients with comorbidity.



This project is funded by the Health Research Council of New Zealand.


Sarfati D. Review of methods to measure comorbidity in cancer populations: no gold standard exists. Journal of Clinical Epidemiology 2012; 65: 924-933.

Gurney, J.K., Sarfati, D., Stanley, J., Dennett, E., Johnson, C., Koea, J., Simpson, A., Studd, R. Unstaged cancer in a population-based registry: Prevalence, predictors and patient prognosis. Cancer Epidemiology 2013; 37: p498-504.

Gurney, J.K., Sarfati, D., Dennett, E., Koea, J. The completeness of cancer treatment data on the national health collections. New Zealand Medical Journal, 2013; 126 (1381): p69-74.

Sarfati, D., Gurney, J., Lim, B.L., Bagheri, N., Simpson, A., Koea, J., Dennett, E. Identifying important comorbidity among cancer populations using administrative data: prevalence and impact on survival. Asia-Pacific Journal of Clinical Oncology 2014; 67(5): 586-95.

Swart, E., Sarfati, S., Cunningham, R., Dennett, E., Signal, V., Gurney, J., Stanley, J. Ethnicity and rectal cancer management in New Zealand. New Zealand Medical Journal 2013; 126(1384): 42-52.

Chamberlain, J., Sarfati, D., Cunningham, R., Koea, J., Gurney, J., Blakely, T. Incidence and management of hepatocellular carcinoma among Māori and non-Māori New Zealanders. Australian & New Zealand Journal of Public Health 2013; 37: 520-6.

Sarfati, D., Gurney, J., Stanley, J., Salmon, C., Crampton, P., Dennett, E., Koea, J., Pearce, N. Cancer-specific administrative data-based comorbidity indices provided valid alternative to Charlson and NHI indices. J Clin Epidemiol 2014; 67(5): 586-95.

Sarfati, D., Lim, B., Gurney, J., Stanley, J., McSherry, C. Development of a Pharmacy-based Comorbidity Index for Patients with Cancer. Medical Care 2014, 52(7): 586-593.

Signal, V., Sarfati, D., Cunningham, R., Gurney, J.,Koea, J., Ellison-Loschmann, L.. Indigenous inequities in the presentation and management of stomach cancer in New Zealand: a country with universal health care coverage. Gastric Cancer 2015, 18(3): 571-579.

Sarfati, D., Gurney, J., Stanley, J., Koea, J. A retrospective cohort study of patients with stomach and liver cancers: the impact of comorbidity and ethnicity on cancer care and outcomes. BMC Cancer 2015, 14(821), p1-11.

Gurney, J., Sarfati, D., Stanley, J.. The impact of patient comorbidity on cancer stage at diagnosis. British Journal of Cancer, In Press.

Cancer, Comorbidity and Care: Key findings from the C3 (Quantitative) Study.


C3 (Quantitative) Study Symposium

In April 2014, the Cancer Control and Screening Research Group convened a final symposium for the C3 (Quantitative) study. The purpose of this symposium was to share the findings of the C3 (Quantitative) study, update progress on the C3 (Qualitative) study, and engage with stakeholders in a discussion about interventions that could result from our work. Each presentation can be viewed below via YouTube links, and slides are also provided in PDF form.

Cancer, Care and Comorbidity

Associate Professor Diana Sarfati presents background information about the intersection between cancer and comorbidity, and summarises the purpose and methods of the 'C3' group of studies. She then discusses the measurement of comorbidity in cancer populations.

C3 (Quantitative) study: Key Findings from the Routinely-Collected Data

Dr Jason Gurney presents the key findings from the routinely-collected data component of the C3 (Quantitative) study.

C3 (Quantitative) study: Key Findings from the Notes Review Data

Associate Professor Diana Sarfati, Dr Ruth Cunningham and Virginia Signal present the key findings from the rectal, liver and stomach cancer notes review data respectively.

C3 (Qualitative) study: Update on Progress

Associate Professor Louise Signal updates progress on the C3 (Qualitative) study.

Self-Management Support in the Secondary Care Setting

Inga O'Brien discusses the usefulness of self-management support in the cancer setting, and presents some of her current PhD work in this area.

C3 studies: Where to from here?

Associate Professor Diana Sarfati sums-up the symposium with a summary of the day's presentations, plus a brief discussion about future directions.

Our people

  • Diana Sarfati (PI); University of Otago, Wellington
  • Chris Cunningham (Co-PI); Massey University
  • Tony Blakely; University of Otago, Wellington
  • Elizabeth Dennett; Colorectal surgeon, Wellington
  • Jason Gurney; University of Otago, Wellington
  • Lis Ellison-Loschmann; Massey University
  • Jonathan Koea; Hepatobiliary surgeon, Auckland
  • Ken Richardson; University of Otago, Wellington
  • Clare Salmond; Biostatistician, Wellington
  • Virginia Signal; University of Otago, Wellington
  • Andrew Simpson; Oncologist, Wellington
  • James Stanley; University of Otago, Wellington

C3 Quantitative Study
Department of Public Health
University of Otago, Wellington
PO Box 7343
Wellington South 6242
New Zealand
Tel 64 4 918 6042
Fax 64 4 389 5319
Email diana.sarfati@otago.ac.nz

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