Tuesday, December 18, 2012

Cross sectional studies


What is research ?
   
It is a scientific process of Systematic collection of data, Compilation of data, analysis of data to convert in to information for suitable interpretation to get the answer of the question

Why research is needed in health sector ?

To identify:

  • Health problems along with their magnitude to prioritize the diseases for action and then to manage  by initiating curative action
  • Risk behavior or causal factors to restrict  partially or fully for further addition by preventive action


Need of research in health sector
6 Ws are the guide for research:

  • W: who are the affected people (age, gender, race)
  • W: where are the affected people (rural/urban, geographical location)
  • W: when are affected (seasonal, cyclic)
  • W: why are affected (cause)
  • W: what action is required (intervention)
  • W: what happened after the action (evaluation of intervention)


Answer of 6 Ws are by different study designs



Cross sectional studies

  • Cross sectional studies are those carried at a point in time or over a short period of time
  • Cross sectional studiesa are useful for both describing the situation in terms of magnitude (prevalence) of disease and comparing (to measure the association), but causal association can not be established
  • While to assess causal association, the cohort study design and case control (for rare diseases) study designs are followed.

Cross-sectional studies measure:

The prevalence of not only disease but also the health related behavior or characteristics of people in a population e.g. the wearing of seat belts or participation in exercise

  • Its result can often suggest causative or risk factors associated with particular illness or behavior
  • For instance, the causal relationship between cataracts and vitamin status was originally investigated through a cross-sectional study (Coggon et al., 2003). 
  • Cross-sectional studies, need not always to investigate the whole population: a sample is usually sufficient, provided that the sample is representative and adequate in size.
  • Cross-sectional studies are useful in planning public health interventions.
Descriptive Cross-sectional survey
are used to measure the prevalence of disease in a population

Example:

  • Repetition of these surveys can be very useful in finding out whether changes are occurring over time – called monitoring or surveillance

Analytical Cross Sectional Surveys
Obtained data on prevalence of outcome and exposure are compared for differences in outcome between exposed and unexposed

  • A defined population at a particular time is considered
  • Exposure and outcomes are determined at the same point in time
  • Analytical Cross Sectional Surveys


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