Material and methods part 1

Material and methods part 2

MATERIAL AND METHODS LAYOUT

CROSS SECTION STUDY

Outline

  • Population/patients
  • Screening
  • Procedures/Survey
  • Definition of variables
  • Ethical clearance
  • Statistical analysis

Population/patients

  • Provide a brief outline of
    • study population
    • clinical services in question
    • Study location/ area
  • participants
  • study areas and disease/ case distribution
  • Location /area where the participants were recruited
    • Hospital base
    • Population base
  • Duration of study: for e.g.  From Nov 1, 2003, to Sept 30, 2014,

Screening/Survey

  • screening / survey method is described with references 
  • staff qualification an training
  • Quality-control measures to check data completeness and consistency.
  • Define questionnaire/investigation/procedures

Procedure

  • Preliminary data
    • demographic data
    • questionnaires
    • surveys
    • examination
  • cases:
    • diagnostic criteria
    • inclusion and exclusion criteria
  • Outcome
    • The primary endpoint
    • Secondary end points

Ethical clearance

  • Written informed consent
  • Study protocol was approved by Regulatory Agency/ethics committee
  • Study was done in accordance with the principles of the Declaration of Helsinki and the International Council for Harmonization Good Clinical Practice guidelines.

Definition of variables

  • Definition of variables
    • Study variables
    • Outcome variables

Statistical analysis

  • Null hypothesis
    • Power and alpha
    • Sample size calculation and expected power of the study.
    • Statistical methods adopted to calculate
  • The primary endpoint
    • primary analysis
      • categorical exposure variables(association between outcome and intervention)
        • Odd ratio
        • Confidence interval, Confidence level
      • Comparative evaluation of any study variable to predict disease
        • logistic regression models
        • model-fitting info
      • Secondary end points
    • Data analysis software

Sample size calculation

  • Confidence level:  95%   p < 0.05, Z= 1.96

  • Confidence level:  99%   p < 0.001, Z= 2.58

CASE CONTROL STUDY

What is a case control study? 

Example of case control study

Outline

  • Population/patients
  • Cases and control
  • Procedures/Survey
  • Definition of variables
  • Ethical clearance
  • Statistical analysis

Population/patients

  • Provide a brief outline of
    • study population
    • clinical services in question
    • Study location/ area
  • participants
  • study areas and disease/ case distribution
  • Location /area where the participants were recruited
    • Hospital base
    • Population base
  • Duration of study: for e.g.  From Nov 1, 2003, to Sept 30, 2014,
  • Sample size
  • Sample size
    • Cases
    • control
  • randomization
    • Matching criteria for cases and controlling
    • Matching ratio between cases and control
    • Recall bias

Cases and control

  • Case and control
    • Inclusion criteria
    • Exclusion criteria
  • Matching criteria (in the video below)
  • Matching ratio

Matching criteria

Procedure

  • Preliminary data
    • demographic data
    • Cases and control

Variables

  • Dependent variable /outcome variable
  • Independent variables /comorbidities

Ethical clearance

  • Written informed consent
  • Study protocol was approved by Regulatory Agency/ethics committee
  • Study was done in accordance with the principles of the Declaration of Helsinki and the International Council for Harmonisation Good Clinical Practice guidelines.

Descriptive analysis of the study variables

  • qualitative variables
    • frequencies and percentages
  • quantitative variables
    • means and SD
  • Differences between means
    • t test for independent data
  • To compare proportions within the group of cases,
    • The χ2test or the Fisher exact test for expected values of less than 5.

Odd ratio

  • to compare the odds of developing primary study outcome( dependent variable) for each co-morbid condition(independent variable)
    • Crude odds ratios (ORs) and 95% confidence intervals (CIs)
    • univariate logistic regression analysis for both groups. 
  • The resulting ORs were also adjusted for matching criteria. 
  • The resulting ORs were also adjusted for matching criteria for case and control. 

Calculating the odds ratio

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