PPHC: L7 Observational Studies II

… study is an observational, analytic study

• Starting point is exposure

Cohort

Key to cohort study:

• Outcomes occurs … exposure

• Participants are … to that outcome(s) so researchers know … that outcome(s) occurred

after, followed up, when

What is the relative risk formula?

Relative risk = risk of outcome among exposed/risk of outcome among unexposed = (a/(a+b))/(c/(c+d))

• RR … 1 = association (exposed group have higher risk of outcome than unexposed group)

• RR … 1 = no association

• RR … 1 = inverse association (exposed group have lower risk of outcome than unexposed group)

>, =, <

RR > 1

• % … = (RR - 1) x 100

• If RR = 1.58 then % … = (1.58 – 1) x 100 = 58% … risk

RR < 1

• % … = (1 - RR) x 100

• If RR = 0.25 then % … = (1 – 0.25) x 100 = 75% … risk

increase, increase, increased, decrease, decrease, decreased

… study is an observational, analytic study

• Starting point is outcome (i.e. disease)

Case-control

Examples and rationale for case-control study:

• When outcome is …

• Outcome (=…)

• When investigating an …, epidemic, pandemic

rare, case, outbreak

Important to analyzing case-control studies:

• … measure … of an outcome because we don’t know when outcomes occurs

  • Case-control study design … involve follow-up

  • In case-control study, one starts at the outcome

• So relevant concept is …

Cannot, risk, does not, odds

Research examples:

• Medications in pregnancy 

  • Pregnant women … from clinical drug trials

  • Analytic observational studies tools for studying perinatal impacts of medications 

• Biologics and pre-term deliveries/small-for-gestational-age births in women with autoimmune disease (… study)

• Antidepressants and pregnancy included hypertension (… study)

excluded, cohort, case control