Colon cancer care and survival: income and insurance are more predictive in the USA, community primary care physician supply more so in Canada

Abstract

BackgroundOur 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.MethodsWe 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.ResultsSignificant 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.ConclusionsPoverty 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.

Palliative chemotherapy among people living in poverty with metastasised colon cancer: facilitation by primary care and health insurance

“…89 Similar to curative treatment barriers observed among those with non-metastasised colon cancer and consistent with this field’s synthetic evidence, 410–13 we and others have observed significant barriers to palliative chemotherapy among people living in poverty with metastasised colon cancer. 51415 Furthermore, our analyses found that prevalent health insurance inadequacies in America accounted for most, but not all of the poverty-based chemotherapy inadequacies, whether the intention was to cure or comfort.…”

“…10 Among California and Ontario samples, a less stringent PCP supply threshold of 7.5 or more PCPs for every 10 000 community inhabitants was protectively associated with 10-year survival. Consistent with Starfield’s further theorising about the benefits of Canada’s stronger primary care orientation, 31 the protective PCP-survival association was stronger in Ontario than California.…”

“…Moreover, among that study’s sample of people with non-metastasised colon cancer, 4 of every 10 in Ontario, but only 1 of every 10 in California lived in such adequately supplied communities. 10 We had access to a contemporaneous sample of people with metastasised colon cancer in Ontario, but unfortunately, it was too small to provide statistically powerful and so confident comparisons. It does, however, suggest again that Canadians are much more likely to live in communities that are very well supplied with PCPs.…”

“…16 Studies in the USA have consistently observed protective associations of primary care physician (PCP) supplies with colon cancer diagnosis, treatment and survival. 101718 Starfield also contended that increased specialist physician (SP) supplies diminish public health by increasing the chances that patients will receive inappropriate or unnecessary specialised care. 19 She centrally theorised that the more specialists, the lower the volume of procedures for each one, unless the rate of performance of procedures also increases.…”

“…18 In contrast, our studies in California observed null to modestly protective association of gastroenter-ologist supplies with disease stage at diagnosis and survival. 1017 However, none of these studies focused specifically on metastasised disease or palliative care, per se. We are not aware of any longitudinal study that has examined the independent, income-adjusted effects of health insurance and physician supplies, PCPs and specialists, on palliative colon cancer care.…”