Patterns of cancer care costs in a country with detailed individual data

Abstract

Objective: To determine health system expenditure on cancers by time since diagnosis using data for an entire country.

Methods: New Zealand cancer registry data was linked to hospitalization, pharmaceutical, outpatient, general practice, laboratory, and other datasets, with costs ascribed to each event occurring in 2006-2011. "Excess" cancer costs were estimated by subtracting "expected costs" for citizens without cancer from the "total cost" for cancer patients ($2011 inflation-adjusted). Gamma regressions were used to estimate costs per person-month.

Results: For first adult cancer diagnosed that the excess cost per person was between US$3400 and US$4300 in the first month postdiagnosis (varied by sex and age), fell to US$50-US$150 per month at 2 or more years postdiagnosis (excluding those within a year of death), but increased again if dying from their cancer (US$3800-US$8300 in the last month of life). Such patterns varied by cancer, for example, in the first month postdiagnosis for 65 year olds it varied 20-fold from US$800 for prostate to US$15,900 for brain cancer. Per diagnosed case, total excess costs varied from US$5000 (melanoma) to US$66,000 (bone and connective tissue) [Corrected]. Excess cancer costs made up 6.5% of total Vote:Health expenditure in 2010-2011, with colorectal (14.7%), breast (14.4%) being the top 2 contributors, and prostate, non-Hodgkin lymphoma, leukemia, and lung each contributing about 6%.

Conclusions: Costs vary substantially by time since diagnosis and cancer type. The results and regression equations reported in this paper can be used in modeling requiring cancer costs by time since diagnosis and proximity to death.

FIGURE 1

Excess health system cost per person per month of “first adult cancer” diagnosis by time preceding and postdiagnosis, separating off the 12 months before death from cancer, by sex and age. Error bars are 95% confidence intervals. Costs in NZ$, inflation-adjusted to 2011, using regression modeling of 2006–2011 data to predict 2011 values.

FIGURE 2

Excess health system costs per person per month for multiple cancers, compared across cancers for 65-year-old males (or females if female-only cancer) for: first month postdiagnosis, and 1–5 months postdiagnosis. Error bars are 95% confidence intervals. Costs in NZ$, inflation-adjusted to 2011.

FIGURE 3

Association of annual excess costs by cancer per diagnosed case, with the 5-year relative survival (RS) ratio for that cancer type. Line is ordinary least squares regression line for equation: cost=16128+(195869×RS)−(214145×RS); where P for RS and RS coefficients were 0.004 and 0.001, respectively. RSR indicate relative survival risk.