Managerial EpidemiologyPart I: Descriptive Epidemiology for

Strategic Planning and Marketing

Ty Borders, Ph.D.

Assistant Professor

Department of Health Services Research & Management

Texas Tech School of Medicine

Learning objectives

– Define epidemiology– Explain the role of epidemiology in health care

management– Explain characteristics of disease transmission

and the development of disease– Calculate descriptive epidemiologic indicators– Identify health-related indicators for strategic

marketing and planning

– Identify sources of health-related indicators

Some basics: What is epidemiology?

• Study of the distribution and determinants of disease in humans

• The doctrine of what is among or happening to people

• Concerned with person, place, and time

History of epidemiology

• 1662, John Graunt – a petty merchandiser in London, publishes a report on births and deaths

in London. First to quantify disease patterns.

• 1839, William Farr– a physician, establishes system for routine compilation of no. and

causes of death in England and Wales

• 1855, John Snow

a physician, studied whether drinking water in Southwark and Vauxhall increased risk of cholera

Some subfields of epidemiology

• Social epidemiology (populations)

• Clinical epidemiology (patients)

• Genetic epidemiology (patients/populations)

• Health services epidemiology (populations/patients)

Health services epidemiology

• Study of the distribution and determinants of health-related events and states

– Utilization of health services

– Health-related quality of life

– Satisfaction with care

Managerial Epidemiology

Epidemiological methods applied to the...

– Assessment of community health for strategic purposes

– Study of the determinants of risk of poor health and overutilization of services strategic purpose

– Assessment and monitoring of health outcomes for quality improvement

Organizational mission and epi

• Children’s Hospital of Wisconsin mission statement

– Provide comprehensive health care services to children appropriate for their special needs

– Provide leadership, experience, and expertise as a community and state resources to advocate for the health and welfare of children……..

Organizational mission and epi

• Mount Sinai, Chicago

– Mount Sinai Hospital Medical Center is committed to the health and well-being of all those we serve. We accomplish this through: (1) Efficient and compassionate delivery of quality health care to our patients, regardless of their ability to pay; (2) Continuous improvement in the quality of the care and service we provide; (3) Leadership that involves and empowers our local communities in the development, advocacy, and implementation of innovative solutions to problems that affect social, economic, and individual health and well-being……...

Why apply epidemiology to strategic planning and

marketing?• Marketing orientation assumes that customer wants

and needs must be met for organizational survival (Ginter, Duncan, & Swayne, Strategic Management of Health Care Org.)

• Market share a key health care organization performance indicator (Griffith, Well Managed Community Hospital)

• But, only about 20% of hospitals are market-oriented (Journal of Health Care Marketing)

Market definition and analysis• Define market

– Geographic (counties, city, city block, zip codes)– Demographic (age, gender)– Scope of services offered (open heart surgery, hernia repairs, primary

care)– Scope of disease treated (diabetes, cancer, depression)

• Determine population size

• Estimate rate of growth – Secondary data sources– Demographic and social indicators

Customer analysis

• Forecast demand from current and new customers– Health status and demographic indicators

– Admission, discharge, and visit data

• Determine unmet health care needs– Rates of preventable diseases

– YPLL

– Social indicator analysis (median family income, % of families in poverty, % unemployed, % teenagers not in school)

– Treatment rate analysis

– Community-based surveys

Strategic Implementation

• Expansion/market development– New service areas, new delivery sites

• Expansion/product development– New products or service lines

• Contraction/decrease scope– Reduce product lines, reduce product variations

– Contraction/decrease service area– Close entire facilities, close unites, limit services to smaller

market areas.

Review: Biologic Concepts

• Agent-Host Environment– An agent interacts with a host in a particular

environment to produce disease (the epidemiologic triangle)

Host

Vector

Agent Environment

Biologic Concepts

• Agent– Infectious, pharmacological, toxicological, injury

• Environment– Biologic (reservoirs, vectors, nutrition)– Social (culture, economics)– Physical (heat, light, personal contact, crowding)

• Host– Behavior, age, genetics, physical status, immunity

Incubation or Induction Period

• The period of time between exposure to a causative agent and the appearance of first clinical manifestations

Infection

Incubation/induction/ latent period

Disease

FatalInapparen

t Mild Moderate Severe

Likely to be seen by doctorLikely to be hospitalized

Disease outbreaks

• Development and maintenance of outbreak depends upon

– Presence of pathogen in sufficient quantities

– Appropriate mode of transmission of pathogen to susceptible persons

– Adequate pool of susceptible persons exposed to pathogen

Characteristics of infectious agents• Pathogenecity

– Ability to cause detectable diseasetotal # of individuals with disease

total # of infected individuals

• Infectivity– Ability to invade and multiply in host

• Virulence– Proportion of cases of disease that result in severe

disease or death

• Immunogenicity– Ability of infection to produce immunity

Mode and source of transmission• Modes

– Person-to-person spread (direct transmission)• e.g., coughing, sexual intercourse, etc.

– Indirect transmission• vehicle born (e.g., contaminated food, water)• vector born (e.g., mosquito)• airborne

• Sources– Common source (e.g., shared water, food)

– Uncommon source (e.g., multiple persons)

Examples of routes of transmission

Agent Disease

Respiratory Cigarette smoke Lung cancer

Influenza virus Flu

Gastrointestinal Vibrio cholera Cholera

Lead Lead poison.

Sexual transm. HIV AIDS

Perinatal exposure Rubella virus Cong. Defects

Blood stream exp. Clostridium tetani Tetanus

& skin breakage

Investigation

• Calculate attack rates among different groups

• Then compare attack rates to identify those at higher risk

• Obtain more detailed information, possibly through surveys, but be aware of potential bias

Termination of disease outbreak

• Usually depends upon

– Removal or elimination of pathogen source

– Blockage of transmission process

– Elimination of susceptibility (e.g., through vaccination or medication)

Assessment of health care needs:Measures of disease occurrence

• 3 measures used to assess the frequency of disease or other health events

– Risk, also referred to as cumulative incidence

– Prevalence

– Incidence density, also called incidence rate

Risk or Cumulative Incidence

Proportion of unaffected individuals who, on average, will contract disease of interest over a specified period of time

Risk or CI = New cases

Persons at risk

R = 0 if no new occurrences arise

R = 1 if the entire population becomes infected

Risk, continued

• Risk factor– Associated with increased risk– Dose, latency, frequency, susceptibility,

multiplicity (multiple causal factors)

• Exposure– Contact with a risk factor– Dose and duration dependent– Direct or indirect

Calculation example

We are interested in the risk of acquiring a nosocomial infection. A study was conducted on 5031 patients5031 patients.

596 patients developed infection within 48 hours after admission.

R = 596 / 5031 = 0.12 = 12%

Prevalence

• Prevalence is a measure of the number of existing cases in a population

• Specifically, the proportion of a population that has a disease at a particular point in time

P = Number of cases

Number of persons in population

Prevalence, like risk, ranges between 0 and 1

Incidence rate or incidence density

• Reflects the occurrence of new cases (like risk), but also measures the rapidity with which event occurs

IR = New cases

Person time

ExamplePatient A develops a disease 2 years after entry into

study. Thus, the person-time for Patient A is 2 years.

Patients B,C,D,E an F contribute 2,3,7,2 and 6 years, respectively. Thus, the number of person-years is 2+2+3+7+2+6 = 22.

IR = new cases/ PT = 1 / 22

Summary

Characteristic Risk Prev. IR

What is Prob. % of pop. Rapiditymeasured of disease with dis. of dis.

Occurrence

Units None None Cases/person-

time

Time of disease Newly Existing Newlydiagnosis diagnosed diagnosed

Synonyms Cumulative - IncidenceIncidence Density

Survival

• Probability of remaining alive for a specific length of time

• For chronic disease, like cancer, 1-year and 5-year survival are important indicators of prognosis and severity.

Calculation of survival

Survival = A - D

A

D = number of deaths observed over a defined period of time

A = number of newly diagnosed patients under observation

Types of data

• Continuous (interval, ratio)

• Categorical (dichotomous, nominal, ordinal)– Frequency distribution– Proportion– Rate– Ratio

Types of descriptive rates

• Crude rates– Rates presented for entire population– e.g. Cancer mortality rate in 1980

(416,481 cancer deaths / midyear U.S. population)

• Category specific rates– Rates presented for individuals in specific

categories– e.g. Cancer deaths among persons 45-54

Adjusted rates

• If we are interested in the magnitude of the health problem, we don’t need adjusted rates

• If we are interested in comparing populations, we need to adjust for differences

Adjustment methods

• Take a weighted average of category-specific rates

• Direct method

• Indirect method

Pros/cons of crude, specific, and adjusted rates

Type Strengths LimitationsCrude Actual summary Difficult to interpret

rates b/c populations may

vary in composition

Specific Homogeneous Cumbersome to compare

subgroups many subgroups of 2

or more populations

Adjusted Summary statistics Fictional rates

Differences in Absolute magnitude

composition removed depends on standard

population chosen

Standardized mortality rate (SMR)

• SMR = observed deaths / expected deaths= indirect adjusted rate / crude rate of

standard pop.

• Usually expressed as a percent

Types of Incidence and Prevalence Measures

Rate Type Numer. Denom.

Morbidity rate Incidence # new nonfatal Total pop.

cases at risk

Mortality rate Incidence # deaths from Total pop.

a disease(s)

Case-fatality rate Incidence # deaths from # of cases

a disease of that disease

Period Prevalence # existing cases Total pop.

plus new cases

diagnosed during

given time period

Age-adjusted cancer morbidity and mortality rates

• All cancers Prostatic• Cervical Lung and bronchial• Colorectal Female breast• Laryngeal Pancreatic• Non-Hodgkin’s lymphoma• Skin melanoma Urinary bladder• Brain Kidney/renal• Ovarian

Age-adjusted mortality rates for other diseases

• Stroke

• Arteriosclerosis

• Diabetes

• Diseases of arteries

• Chronic obstructive pulmonary disease (COPD)

• Pneumonia and influenza rate

• Chronic liver disease and cirrhosis

Age-adjusted injury morbidity and mortality rates

• Stroke

• Arteriosclerosis

• Diabetes

• Diseases of arteries

• Chronic obstructive pulmonary disease (COPD)

• Pneumonia and influenza rate

• Chronic liver disease and cirrhosis

Crude infectious disease rates

• Syphilis incidence rate

• Chlamydia incidence rate

• Gonorrhea incidence rate

• Tuberculosis incidence rate

Youth health data

• % of live births to teens

• Fetal mortality rate

• Infant mortality rate

• Homicide mortality rate ages 15-19

• Suicide mortality rate ages 15-19

• % of extramarital live births to teens

• Founded cases of child birth

Socioeconomic data

• Per capita income

• Unemployment rate

• % of population below 200% of poverty level

• % of population with at least a baccalaureate degree

• % of population Medicaid eligible

• Population density

Years of potential life lost (in 1,000s) from leading causes of cancer, 1991 (from Greenberg, 1996)

2145

845

754

352

342

0 500 1000 1500 2000 2500

Lung

Breast

Colon/rectum

Pancreas

Leukemias

Years of Potential Life Lost before age 65 by cause of death (per 100,000 person years) (from Greenberg,

1996)

935

843

628

395

347

0 200 400 600 800 1000

Injuries

Cancer

Heart disease

Homicide

HIV infection

Health-Related Data Sources

• Texas Department of Health

• U.S. Census Bureau

• Centers for Disease Control

• Health Resources and Services Administration

• Surveys

Health-Related Data Sources

• Group records

– Centers for Medicare and Medicaid Services (CMS)

• DRGs

– BCBS, insurance companies, HMOs

• ICD-9 codes, CPT-codes