Rates are the hallmark for epidemiology for they form the basis of comparisons between population groups

Rose and Barker,1986

“The Price of Health, like that of liberty, is Eternal Vigilance”

“An improvement in the treatment of disease, and any addition to medical science, will tend ultimately to the diminution of human suffering; but the registration of the causes of death is calculated to exercise a still more direct influence upon public health. Diseases are more easily prevented than cured, and the first step to their prevention is the discovery of their exciting causes by numerical facts and measure the intensity of their influence.”

William Farr, 1839

Exclusively Rural AreasDoctors sent to rural areasLeper census, 1836 (5), 1845 (8), 1845 (11)Leprosy viewed as inheritable--sexual isolation, hospitals, prohibiting marriageNo experience in setting up the registrationLocal Health officerRoyal Decree

Problems with local registration(definition, deadlines,

incomplete)Circular lettersChief Medical Officer travelling to each areaOver diagnosis initially (acne, scabies)Low prevalence areas, disease overlookedUndercount, Undercount, UndercountIsolation: Areas where isolation practiced, most rapid decline in disease

Definitions

Reducing the incidence of disease (primary prevention)Reducing the prevalence of disease (second. prevent.)

Ongoing operations or programs aimed at reducing the incidence and/or prevalence of disease

Prevention

Control

Last, Dictionary of Epidemiology

General Motors sold 2,542,455Automobiles World Wide

99 Billion Sold

NCDs

What is the incidence of Diabetes?

What is the incidence of CHD?

What is the incidence of Cancer?

Nobody Knows

Surveillance

Health Dept.

Continuous analysis, interpretation, and feedback of systematically collected data, generalized using methods distinguished by their practicality, uniformity, and rapidity, rather than by accuracy or completeness. Last, Dictionary of Epidemiology

0

20

40

60

80

100

120

Month

Num

ber o

f Cas

es Total CasesReported CasesTypical Pattern

TV says Flu

CDC Comes in

Registry

Academia

…the term register is applied to the file of data concerning all cases of a particular disease or health -relevant condition in a defined population such that the cases can be related to a population base. Last, Dictionary of Epidemiology

Disease Monitoring Systems

Surveillance RegistriesDisease Infectious ChronicCoverage Large SmallCost Low HighSpeed Fast SlowAscertainment Low/Variable Presumed

High

Allegheny County Type I Diabetes Registry

1. Diagnosed between 1/1/65 and 12/31/992. Age at onset <203. Diagnosis of Diabetes4. On Insulin at time of Hospital Discharge5. Resident of Allegheny County at Diagnosis

/100,000/100,000

16 Undercount

Allegheny County Type I Diabetes Registry

Registry

WHO DiaMond ProjectWHO DiaMond Project

EpidemiologistsCounting Disease

Prairie Chicken

Biostatistics

1 2 3 4 5 6 7 8 9

Capture

Mark

RECAPTURE

N= (M+1)(n+1)(m+1) -1

N = Estimate of NumberM =Number in First Samplen = Number in Second Samplem =Number of “marked” items in Second Sample

Var(N)=(M+1)(n+1)(M-m)(n-m)

(m+1) (m+2)

Sample 1 Sample 2

M mn

In Common

Capture-Recapture

2

Capture-Recapture Methods

Long history of use in Demographyi.e. US Census

The standard for estimating the abundance or shortage of wildlife populations

Fish Disease

Net ListTag Name/

IdentifierRecapture Duplicate

Lower ExtremityAmputation Study

Adolescent InjuriesSports injuriesDog Bites

Optimal “Lists” to identify cases

IndependentReasonable ascertainmentInexpensive

Comparison of “lists to gold standard”CR to Registry

Good monitoring does not necessarily ensure the making of right decisions, but it reduces the risk of wrong ones.

Languimer, 1963

Public Health

Cancer Incidence in Middle East

Good monitoring does not necessarily ensure the making of right decisions, but it reduces the risk of wrong ones.

Languimer, 1963

Porpoises can teachEpidemiologists how to

count