Mother and Child Health: Research Methods

1
Mother and Child Health Research Methods

• G.J.Ebrahim
• Editor
• Journal of Tropical Pediatrics, Oxford University
  Press.

2
Preparing Case Series

• All cases admitted in the time period must be
  included. One needs
• Precise Inclusion and exclusion criteria
• What intervention was carried out for each
  patient, their progress and the outcome.
• Influence of all variables should be accounted
  for.
• Follow a pre-planned protocol. Give thought to
  how missing values, drop-outs and out-migration
  are to be handled.
• Temporal drift is a constant danger if series
  need to be collected over a long time.

3
Cross-sectional Studies

• Cross-sectional studies are studies of
  prevalence. Proportion with an attribute or
  disease / Number of subjects Prevalence.
• 3 important questions to consider
• Definition of Case
• Definition of the Population
• Are cases and non-cases from an unbiased sample
  of the population?

4
Preparing Cross-sectional Studies

• In Cross-sectional studies think of
• Sampling Procedures.
• Clear definition of Target Population.
• Clear definition of outcome.
• Clear definition of risk factors.
• Remember Confounders.
• Remember seasonal variations.

5
Advantages and Disadvantages of Cross- sectional
Studies

• Advantages
• Useful for descriptive studies
• Rapid, inexpensive, can provide analytic clues.
• Less prone to error about exposure recall and
  bias

• Disadvantages
• Unable to sort out what came first exposure or
  outcome
• Prone to sample distortion bias.

6
Main uses of Cross-sectional Studies

• Identify and describe a problem.
• Collect information for planning e.g. surveys of
  immunisation, antenatal care, coverage.
• Evaluate utilisation rates of services.
• Monitoring health status of a community by
  regular repeated surveys.

7
Using Cross-sectional Studies for Hypotheses
Formulation

• Method of Difference.
• If frequency of a disease is markedly different
  between two groups then it is likely to be caused
  by a particular factor that differs between them.
• Method of Agreement.
• If a factor commonly occurs in which a disease
  occurs with high frequency then the factor is
  very likely associated with the disease.
• Concomitant variation. Frequency of a factor
  varies in proportion to frequency of disease.

8
Surveys

• Surveys are a form of cross-sectional studies
  used for
• Assessing attitudes, opinions or beliefs
• To study characteristics of populations regarding
  behaviour e.g. health service utilisation drug
  use smoking alcohol consumption etc.
• Information about socio-demographic
  characteristics

9
Modification of Cross-sectional Studies - I
Trend Design
Future
Sampling
Population
Risk Factor
Present
Disease Prevalence
Risk Factor
Sampling
Disease Prevalence
10
Modification of Cross-sectional Studies - II
Panel Design
Present
Future
Risk Factor
Risk Factor
Population
Disease Prevalence
Disease Prevalence
Same Sample
Sample