Mother and Child Health: Research Methods G.J.Ebrahim Editor Journal of Tropical Pediatrics, Oxford University Press.

Noxious agent and illness - 1 Smoking Lung cancer Chronic Respiratory Disease Peptic ulcer Coronary Artery Disease

Noxious Agent and Illness - 2 Coronary Artery Disease Smoking Hypertension Lack of exercise Obesity High blood cholesterol

Effect Modifiers Susceptible host Crowding Malnutrition Very young or old age Not immunized Infection Exposure to Mycobacterium

Establishing cause-effect Relationship Strength of Research Design is most important 1. Well - conducted randomized controlled trials (adequate sample size; blinding; standardized methods of measurement and analysis) 2. Cohort studies - next best ( minimize selection & measurement bias; check for confounders)

Evidence Required Temporal sequence (cause must precede effect) Strength of association (Relative risk or odds ratio) Dose-Response relationship Reversible association (removal of cause decreases risk) Consistency (several studies come up with same findings) Biological plausibility Specificity Analogy

A Flow Chart Association (O.R. R.R. Pearson’s r) YesNo BiasNot likely Likely ChanceExcludedPossible Error No Possible CAUSE

Evidence provided by study designs Clinical Trials Temporality Cohort Study Strength of Association Case-control StudyReversibility Case SeriesBiological plausibility Strong Weak