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Managerial Epidemiology
Part 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
Inapparent
Mild
Disease
Moderate Severe
Fatal
Likely to be seen by doctor
Likely 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 disease
total # 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
Respiratory
Cigarette smoke
Influenza virus
Gastrointestinal Vibrio cholera
Lead
Sexual transm.
HIV
Perinatal exposure Rubella virus
Blood stream exp. Clostridium tetani
& skin breakage
Disease
Lung cancer
Flu
Cholera
Lead poison.
AIDS
Cong. Defects
Tetanus
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 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
Example
Patient 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
measured
Prob.
of disease
% of pop.
with dis.
Rapidity
of dis.
Occurrence
Units
None
None
Cases/persontime
Time of disease
diagnosis
Newly
diagnosed
Existing
Newly
diagnosed
Synonyms
Cumulative
Incidence
-
Incidence
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 categoryspecific rates
• Direct method
• Indirect method
Pros/cons of crude, specific, and
adjusted rates
Type
Strengths
Crude
Actual summary
rates
Specific
Adjusted
Limitations
Difficult to interpret
b/c populations may
vary in composition
Homogeneous
Cumbersome to compare
subgroups
many subgroups of 2
or more populations
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
Mortality rate
Incidence
Case-fatality rate
Incidence
Period
Prevalence
# new nonfatal
Total pop.
cases
at risk
# deaths from
Total pop.
a disease(s)
# deaths from
# of cases
a disease
of that disease
# 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)
Leukemias
342
Pancreas
352
Colon/rectum
754
Breast
845
Lung
2145
0
500
1000
1500
2000
2500
Years of Potential Life Lost before age 65 by cause
of death (per 100,000 person years) (from Greenberg, 1996)
HIV infection
347
Homicide
395
Heart disease
628
Cancer
843
Injuries
935
0
200
400
600
800
1000
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