wilfried karmaus department of epidemiology, msu karmaus@msu.edu epi 824 reproductive epidemiology...

Wilfried Karmaus

Department of Epidemiology, MSU

karmaus@msu.edu

EPI 824Reproductive Epidemiology

Fall 2002

Objectives (1)Objectives (1)

• Level 6: Evaluation (critique, appraise, Level 6: Evaluation (critique, appraise,

judge)judge)

• Level 5: Synthesize (integrate, Level 5: Synthesize (integrate,

collaborate)collaborate)

• Level 4: Analyze (hypothesis, structure)Level 4: Analyze (hypothesis, structure)

• Level 3: Application (utilize, produce)Level 3: Application (utilize, produce)

• Level 2: Comprehension (translate, Level 2: Comprehension (translate,

discuss)discuss)

• Level 1: Knowledge (define, enumerate, Level 1: Knowledge (define, enumerate,

recall) recall)

Problem Solving Cycle in Public Problem Solving Cycle in Public HealthHealth

Definition of the problem

Goals and priority setting

Studying the effects

Application and steering of the

measures

Strategies forproblem solving

Operational plan

Epidemiology: (Stallones 1980, Ann Rev Public Health 1:69-82)

Axiom: Disease does not distribute randomly

in human populations.Corollary 1: Aggregations of human diseases

are manifested along axes of:• time• space• individual / group characteristics.

Corollary 2: Variations in the frequency of

human disease occur in response to:• variation in exposure• variation in susceptibility.

Outcomes of human reproduction

Reproductive health Sex ratio

Predictors OutcomesGeneral etiologic model:

X1 X2

X3

Y1

problem: collinearity

Y2

Y3

(atopic eczema)

(increased cholesterol)

(bronchial hyperreactivity)

Latent factor for these three outcomes?

Predictors Outcomes

X1 X2

X3

Y1

problem: collinearity

Y2

Y3

(infertility)

(fetal loss)

(birth defect)

conditional interdependence(selective survival)

Etiologic model for reproductive epidemiology:

=

=

Frequency of reproductive outcomes in Frequency of reproductive outcomes in humanshumans

Infertility/Subfecundity » 14-20% of all couples at risk

Spontaneous abortions recognized: » 15% of all conceptions not recognized: » 20%

malformations » 2-5% of all live births

childhood cancer » 0.18% of all children

Initiation of the etiologic process (onset of the first cause)

Initiation of the patholo-gic process (disease starts)

Clinical detection of the disease (onset of sign and symptoms)

Outcome of the disease(subsequent change in health status or death)

Latency Duration

Primary Prevention Secondary Prevention Tertiary Prevention

Low birth weight and exposure to wood preservatives (PCP, PCDD/F)

Source: Karmaus et. al. 1995

% without conception

exposed at starting time (n=86)

not exposed at starting time (n=1001)

0.0

0.2

0.4

0.6

0.8

1.0

months

0 6 12 18 24 30 36 42 48 54 60

Living on a contaminated waste site and time to pregnancy

Study design in reproductive epidemiology golden standard = prospective study

time

starting time of unprotected intercourse

detected/ recognized conception

birth, miscarriage, stillbirth

starting time end of unprotec-ted intercourse

time to pregancy

period of unprotected intercourse

gestational age

Changes in sex ratioProportion of female newborns and mother’sresidence in the Bille-settlement before conception(Küppers et al. 1997)

born between

1950-1960

(F1-Genertation)

born between

1960-1970

(F1-generation)

born

after 1970

(F2-generation)

notexposed

exposed notexposed

exposed notexposed

exposed

n=83 n=44 n=67 n=48 n=101 n=81

47.0 47.7 53.7 50.0 44.6 29.6

Reproductive epidemiology includes a wide variety of outcomes with:

• different ways of measurements• different markers within physiologic and

pathologic processes• different statistical approaches

In the course you will learn- how to define reproductive outcomes- to review one outcomes and its etiology- to discuss empirical methods and - to apply some statistical methods.