Colon cancer care and survival: income and insurance are more predictive in the USA, community primary care physician supply more so in Canada.
BACKGROUND
Our research group advanced a health insurance theory to explain Canada's cancer care advantages over America. The late Barbara Starfield theorized that Canada's greater primary care-orientation also plays a critically protective role. We tested the resultant Starfield-Gorey theory by examining the effects of poverty, health insurance and physician supplies, primary care and specialists, on colon cancer care in Ontario and California.


METHODS
We analyzed registry data for people with non-metastasized colon cancer from Ontario (n = 2,060) and California (n = 4,574) diagnosed between 1996 and 2000 and followed to 2010. We obtained census tract-based socioeconomic data from population censuses and data on county-level physician supplies from national repositories: primary care physicians, gastroenterologists and other specialists. High poverty neighborhoods were oversampled and the criterion was 10 year survival. Hypotheses were explored with standardized rate ratios (RR) and tested with logistic regression models.


RESULTS
Significant inverse associations of poverty (RR = 0.79) and inadequate health insurance (RR = 0.80) with survival were observed in the California, while they were non-significant or non-existent in Ontario. The direct associations of primary care physician (RRs of 1.32 versus 1.11) and gastroenterologist (RRs of 1.56 versus 1.15) supplies with survival were both stronger in Ontario than California. The supply of primary care physicians took precedence. Probably mediated through the initial course of treatment, it largely explained the Canadian advantage.


CONCLUSIONS
Poverty and health insurance were more predictive in the USA, community physician supplies more so in Canada. Canada's primary care protections were greatest among the most socioeconomically vulnerable. The protective effects of Canadian health care prior to enactment of the Affordable Care Act (ACA) clearly suggested the following. Notwithstanding the importance of insuring all, strengthening America's system of primary care will probably be the best way to ensure that the ACA's full benefits are realized. Finally, Canada's strong primary care system ought to be maintained.
School of Social Work, University of Windsor, 401 Sunset Avenue, Windsor, Ontario, N9B 3P4, Canada. gorey@uwindsor.ca.
Kevin M
KM
Gorey
Department of Oncology, Windsor Regional Cancer Center and Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada. Sindu.Kanjeekal@wrh.on.ca.
Sindu M
SM
Kanjeekal
Division of General Surgery, Sunnybrook Health Sciences Center and cross appointed Departments of Surgery and Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada. frances.wright@sunnybrook.ca.
Frances C
FC
Wright
Department of Oncology, Windsor Regional Cancer Center and Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada. caroline.hamm@wrh.on.ca.
Caroline
C
Hamm
Department of Geography, Western University, London, Ontario, Canada. iluginaa@uwo.ca.
Isaac N
IN
Luginaah
Faculty of Health Sciences, University of Ontario Institute of Technology, Oshawa, Ontario, Canada. emma.bartfay@uoit.ca.
Emma
E
Bartfay
Department of Epidemiology and Biostatistics and Robarts Research Institute, Western University, London, Ontario, Canada. gy.zou@robartsinc.com.
Guangyong
G
Zou
Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada. eric.holowaty@sympatico.ca.
Eric J
EJ
Holowaty
School of Social Work, University of Windsor, Ontario, Canada. nrichter@uwindsor.ca.
Nancy L
NL
Richter
D002140:California / Q000453:epidemiology; D003110:Colonic Neoplasms / Q000191:economics / Q000401:mortality* / Q000628:therapy; D005762:Gastroenterology; D054625:Healthcare Disparities / Q000191:economics; D006801:Humans; D019458:Insurance Coverage / Q000191:economics; D009864:Ontario / Q000453:epidemiology; D058007:Physicians, Primary Care / Q000600:supply & distribution*; D000078329:Workforce