Summary Measures of Population Health: Measuring the impact of disease, injuries and risk factors

Objectives To derive internally consistent estimates of incidence, prevalence, disease progression and mortality for over 100 disease and injury categories –Communicable, maternal, perinatal and nutritional conditions –Non-communicable diseases –Injuries To elicit a numerical value (weight) reflecting the general population’s relative preference for each disease/disability state on an interval scale

Summary Measures of Population Health (SMPH) Expectancy - life years lived –Health Adjusted Life Expectancy (HALE) –Disability Adjusted Life Expectancy (DALE) –Disability Free Life Expectancy (DFLE) Gap - life years lost (compared to ideal) –Disability Adjusted Life Year (DALY) –Health Adjusted Life Years Lost (HALY)

Calculating HALYs HALY = YERF + YLL “Full Health” “Partial Health” “Premature mortality” Years of Life Lost due to premature mortality (YLL) Year Equivalents of life lost due to Reduced Functioning (YERF) + Disease (Stage and Severity) Birth Death Potential limits to life = Health Adjusted Life Years lost

Calculating YLL Death Life Expectancy Years of life lost to premature mortality YLL= M * L where M = number of deaths L = remaining life expectancy

Calculating YERFs Disease Death Years of life lived with the disease YERF= I * (1-P) * D where I = incident cases P = preference score D = average duration model

Key inputs to summary measures Mortality by age, sex and cause Epidemiological data on non-fatal health outcomes by age, sex and cause Valuations of health states

Top 10 Leading Causes of Death and DALYs (data from Canada) Leading cause of death 1 Ischaemic heart disease 2 Stroke 3 Lung Cancer 4 COPD 5 Colorectal cancer 6 Dementia 7 Diabetes mellitus 8 Prostate Cancer 9 Breast Cancer 10 Suicide DALYs 1 Ischaemic heart disease 2 Stroke 3 COPD 4 Depression 5 Lung cancer 6 Dementia 7 Diabetes mellitus 8 Colorectal cancer 9 Asthma 10 Osteoarthritis

Unsafe sex Occupation Illicit drugs High blood cholesterol Lack of fruit/veg. Obesity Alcohol benefit Alcohol harm High blood pressure Physical inactivity Tobacco Attributable DALYs as a proportion of total DALYs YLL YLD Burden attributable to 10 risk factors

HALY Total for top 15 cancers

Attribution of total HALYS for all cancers combined to Risk Factors Total = 49%

Part 2: Weighting of Health States To elicit a numerical value (preference score) on an interval scale reflecting the population’s relative preference for health states Describe health in terms of functional status or capacity

Eliciting Health State Preferences Methods Tested: Visual Analog Scale (VAS) Standard Gamble (SG) Time Trade Off (TTO) Person Trade Off (PTO)

Visual Analog Scale Death Full Health Poor Health

Standard Gamble Give instantaneous and lasting improvement to full health with probability p Give immediate death with probability 1-p You have a lifelong stationary impaired health state and are given a choice. Do you take a hypothetical procedure that will:

Time Trade-Off Years of healthy life you would give up to avoid living in a state of poor health

Person Trade Off (PTO) 1,000 healthy individuals N  1,000 individuals in a disabling health state