Population health impact of cancer in Canada, 2001.

Summary measures of population health that incorporate morbidity provide a new perspective for health policy and priority setting. Health-adjusted life years (HALYs) lost to a disease combine the impact of years of life lost to premature mortality and morbidity, measured as year-equivalents lost to reduced functioning. HALYs for 25 cancers were estimated from mortality and incidence in 2001 in Canada; population-attributable fractions were estimated for major risk factors contributing to these cancers. Results from this analysis indicate that Canadians would lose an estimated 905,000 health-adjusted years of life to cancer for 2001, including 771,000 to premature mortality and 134,000 to morbidity from incident cases (years discounted at 3 percent). Most of the estimated premature mortality was due to lung cancer; morbidity was largely due to breast, prostate and colorectal cancers. An estimated one quarter of HALYs lost to cancer were attributable to smoking and almost one quarter were attributable to alcohol consumption, lack of fruit and vegetables, obesity and physical inactivity combined. These results are a significant advance in measuring the population health impact of cancer in Canada because they incorporate morbidity as well as mortality.

Descriptive epidemiology of osteoarthritis in British Columbia, Canada.

OBJECTIVE: Osteoarthritis (OA) is a highly prevalent and often disabling disease. Data on the incidence of OA in the general population are limited. Our objectives were (1) to estimate OA prevalence and incidence rates by age and sex in a geographically defined population of 4 million people [British Columbia (BC), Canada] using an administrative database; and (2) to determine the effects of different administrative definitions of OA and observation (run-in) time on such estimates. METHODS: We used data on all visits to health professionals and hospital admissions covered by the Medical Services Plan (MSP) of BC for the fiscal years 1991-92 through 2000-01. OA was defined based on International Classification of Diseases, 9th Revision, diagnostic codes required for administrative purposes. RESULTS: The overall prevalence of OA in 2001 was 10.8%: 8.9% in men and 12.6% in women. Prevalence was higher in women in all age groups. By age 70-74 years, about one-third of men and 40% of women had OA. Incidence rates in 2000-01 were 11.7 per 1000 person-years in the total population, 10.0 in men and 13.4 in women. Rates increased linearly with age between 50 and 80 years. Both prevalence and incidence depended strongly on the definition of OA and the run-in period. CONCLUSION: Prevalence of physician-diagnosed OA in BC was slightly lower than self-reported prevalence of arthritis in population surveys. Routinely collected administrative data could be a valuable source of information for OA surveillance, but more research is needed on the validity of OA diagnosis in administrative databases.

Deriving utility scores for co-morbid conditions: a test of the multiplicative model for combining individual condition scores.

BACKGROUND: The co-morbidity of health conditions is becoming a significant health issue, particularly as populations age, and presents important methodological challenges for population health research. For example, the calculation of summary measures of population health (SMPH) can be compromised if co-morbidity is not taken into account. One popular co-morbidity adjustment used in SMPH computations relies on a straightforward multiplicative combination of the severity weights for the individual conditions involved. While the convenience and simplicity of the multiplicative model are attractive, its appropriateness has yet to be formally tested. The primary objective of the current study was therefore to examine the empirical evidence in support of this approach. METHODS: The present study drew on information on the prevalence of chronic conditions and a utility-based measure of health-related quality of life (HRQoL), namely the Health Utilities Index Mark 3 (HUI3), available from Cycle 1.1 of the Canadian Community Health Survey (CCHS; 2000-01). Average HUI3 scores were computed for both single and co-morbid conditions, and were also purified by statistically removing the loss of functional health due to health problems other than the chronic conditions reported. The co-morbidity rule was specified as a multiplicative combination of the purified average observed HUI3 utility scores for the individual conditions involved, with the addition of a synergy coefficient s for capturing any interaction between the conditions not explained by the product of their utilities. The fit of the model to the purified average observed utilities for the co-morbid conditions was optimized using ordinary least squares regression to estimate s. Replicability of the results was assessed by applying the method to triple co-morbidities from the CCHS cycle 1.1 database, as well as to double and triple co-morbidities from cycle 2.1 of the CCHS (2003-04). RESULTS: Model fit was optimized at s = .99 (i.e., essentially a straightforward multiplicative model). These results were closely replicated with triple co-morbidities reported on CCHS 2000-01, as well as with double and triple co-morbidities reported on CCHS 2003-04. CONCLUSION: The findings support the simple multiplicative model for computing utilities for co-morbid conditions from the utilities for the individual conditions involved. Future work using a wider variety of conditions and data sources could serve to further evaluate and refine the approach.

Obesity--a growing issue.

OBJECTIVES: This article, based on longitudinal data, follows a sample of people who were aged 20 to 56 in 1994/95 to determine the percentage who made the transition from normal to overweight, or from overweight to obese by 2002/03. Characteristics that increased the chances of overweight people becoming obese are examined. DATA SOURCES: The data are from five cycles of the National Population Health Survey, 1994/95 through 2002/03. ANALYTICAL TECHNIQUES: Cox proportional hazards modelling was used to identify variables associated with an increased or decreased risk of becoming obese; 1,937 men and 1,184 women who were overweight in 1994/95 were selected. MAIN RESULTS: Close to a third (32%) of people who were aged 20 to 56 and of normal weight in 1994/95 had become overweight by 2002/03. During the same period, almost a quarter of those who had been overweight in 1994/95 had become obese. Among people who were overweight, the risk of obesity was relatively high for younger men and members of low-income households. Overweight men who smoked or who had activity restrictions had a high risk of obesity. Physical activity helped women avoid obesity.

Estimating summary measures of health: a structured workbook approach.

BACKGROUND: Summary measures of health that combine mortality and morbidity into a single indicator are being estimated in the Canadian context for approximately 200 diseases and conditions. To manage the large amount of data and calculations for this many diseases, we have developed a structured workbook system with easy to use tools. We expect this system will be attractive to researchers from other countries or regions of Canada who are interested in estimating the health-adjusted life years (HALYs) lost to premature mortality and year-equivalents lost to reduced functioning, as well as population attributable fractions (PAFs) associated with risk factors. This paper describes the workbook system using cancers as an example, and includes the entire system as a free, downloadable package. METHODS: The workbook system was developed in Excel and runs on a personal computer. It is a database system that stores data on population structure, mortality, incidence, distributions of cases entering a multitude of health states, durations of time spent in health states, preference scores that weight for severity, life table estimates of life expectancies, and risk factor prevalence and relative risks. The tools are Excel files with embedded macro programs. The main tool generates workbooks that estimate HALY, one per disease, by copying data from the database into a pre-defined template. Other tools summarize the HALY results across diseases for easy analysis. RESULTS: The downloadable zip file contains the database files initialized with Canadian data for cancers, the tools, templates and workbooks that estimate PAF and a user guide. The workbooks that estimate HALY are generated from the system at a rate of approximately one minute per disease. The resulting workbooks are self-contained and can be used directly to explore the details of a particular disease. Results can be discounted at different rates through simple parameter modification. CONCLUSION: The structured workbook approach offers researchers an efficient, easy to use, and easy to understand set of tools for estimating HALY and PAF summary measures for their country or region of interest.

Potential impact of population-based colorectal cancer screening in Canada.

Randomized controlled trials (RCT) have shown the efficacy of screening for colorectal cancer (CRC) using the faecal occult blood test (FOBT) with follow-up by colonoscopy. We evaluated the potential impact of population-based screening by FOBT followed by colonoscopy in Canada: mortality reduction, cost-effectiveness, and resource requirements. The microsimulation model POHEM was adapted to simulate CRC screening using Canadian data and RCT results about test sensitivity and specificity, participation, incidence, staging, progression, mortality and direct health care costs. In Canada, biennial screening of 67% of individuals aged 50-74 in the year 2000 resulted in an estimated 10-year CRC mortality reduction of 16.7%. The life expectancy of the cohort increased by 15 days on average and the demand for colonoscopy rose by 15% in the first year. The estimated cost of screening was $112 million per year or $11,907 per life-year gained (discounted at 5%). Potential effectiveness would depend on reaching target participation rates and finding resources to meet the demand for FOBT and colonoscopy. This work was conducted in support of the National Committee on Colorectal Cancer Screening.

Lifetime costs of colon and rectal cancer management in Canada.

Colorectal cancer is the second leading cause of cancer-related mortality among Canadians. We derived the direct health care costs associated with the lifetime management of an estimated 16,856 patients with a diagnosis of colon and rectal cancer in Canada in 2000. Information on diagnostic approaches, treatment algorithms, follow-up and care at disease progression was obtained from various databases and was integrated into Statistics Canada's Population Health Model (POHEM) to estimate lifetime costs. The average lifetime cost (in Canadian dollars) of managing patients with colorectal cancer ranged from $20,319 per case for TNM stage I colon cancer to $39,182 per case for stage III rectal cancer. The total lifetime treatment cost for the cohort of patients in 2000 was estimated to be over $333 million for colon and $187 million for rectal cancer. Hospitalization represented 65% and 61% of the lifetime costs of colon and rectal cancer respectively. Disease costing models can be important policy- relevant tools to assist in resource allocation. Our results highlight the importance of performing preoperative tests and staging in an ambulatory care setting, where possible, to achieve optimal cost efficiencies. Similarly, terminal care might be delivered more efficiently in the home environment or in palliative care units.