Diabetes and Risk Factors How to conduct prevalence studies Dhaka, August 1, 2005 A. Samad Shera, TI, SI, FRCP Honorary President, International Diabetes Federation (IDF) Director, WHO Collaborating Centre Member, WHO International Expert Advisory Panel on Diabetes Member, European Expert Committee on Diabetes in Immigrants to Europe National Coordinator for Diabetes Control Secretary General, Diabetic Association of Pakistan Member Syndicate, Liaquat University of Medicine and Health Sciences, Hyderabad - Sindh

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A-PLANNING THE STUDY A number of steps are required from the moment of decision to undertake a study, until the practical preparation can commence

B-PREPARING THE STUDY a) b) c) Selecting the survey site: Choose a central survey site , to which a predermined number of subjects are invited each day, Characteristics of a survey site 1- Indoors or Shamians 2- Adequate waiting ------- 3- Simple flow of subjects 4- Privacy for anthropometric measurements. 5- Quiet environment for BP measurement

C- PREPARING FOR THE STUDY a) Obtaining Approval b) Choosing the team leader c) Selecting the study site d) The Pre-Study census e) Preparing the chosen subjects for the study f) Team training g) Quality assurance

D- CONDUCTING THE STUDY a) Study Procedures 1) Registration 2) Fasting blood sample 3) Glucose drink 4) Two hour blood sample b) Anthropometry c) Questionnaire d) Blood pressure Continued

h) Providing general health care I) Providing feed back Continued e) Final assessment f) Non response g) Over response h) Providing general health care I) Providing feed back j) Transport of specimens

E- SPECIFICATION OF DATA TO BE COLLECTED Collect data related to the topics of immediate interest Resist to collect “opportunistic” data which serve no obvious purpose

1) Core data: Include basic demographic information, medical and family history, lifestyle factors, key physical parameters (BP,GT,Anthropometry and blood lipids) 2) Optimal data: Addition material which might include dietry habits, genetic markers, evidence of disease complications etc

b) Specification of study procedure c) Specification of Laboratory procedures d) Choice of statistical methods e) Selecting the most appropriate range f) Preparing the survey form (example of our survey form for National Survey) Continued

g) Selecting the survey sample Continued g) Selecting the survey sample a) Simple random sampling b) Multistage sampling c) Cluster sampling h) Sample size determination i) Choosing the team size and composition j) Preparing a written protocol

F- HANDLING THE DATA Data Entry Data Analysis a) Data entry / editing b) Data verification Data Analysis a) Create variable b) Run Analysis c) Create Charts

G-PREPAING THE SURVEY FORM Examiner enters into appropriate box the numerical code of the correct response Almost all coded responses are to be found at the right hand margin of this form The form only includes key item and is short enough to fit on two sides of a single sheet of paper

H-SELECTING THE SURVEY SAMPLE Simple Random Sampling: Subjects normally recruited from a list such as recent electoral role. The method is labour intensive Multistage Sampling: The community is first divided into subgroups on the basis of ethnicity, ----------, socio-economical level, age group or sex. Multistage sampling is useful when over sampling under representative groups is required e.g, a minority population or elderly age groups Cluster Sample: Simplest method in Procter

I- PREPARING THE REPORT a) Introduction b) Survey methods c) Response d) Results e) Discussion f) Conclusions g) Tables and figures