Malawi Epidemiology and Intervention Research Unit Non-Communicable Disease Survey data, 2013-2017 - User Guide

Persistent Identifier

https://doi.org/10.17037/DATA.00000961

Data Description

Data from a cross-sectional survey on non-communicable diseases and their risk factors carried out between 2013 and 2017 in one rural and one urban site in Malawi by the Malawi Epidemiology Intervention Research Unit (MEIRU). Data also include some anthropometric measures and laboratory test results, and self-report data relating to socio-economic status.

Data Collection Methods

Electronic data collection method was used with the Open Data Kit (ODK) software on tablets. Interviews were conducted face-to-face by trained local staff, at the household of each participant in the local language. The majority of the data come from this face-to-face questionnaire, with some data coming from lab test results, and anthropometry measurements (carried out in the field at the same time as the questionnaire).

Data Analysis and Preparation

Data from questionnaire and lab sources for the two sites were combined and then the two site’s data appended together. New variables were created from the raw data to assist analysis and anonymisation processes (see ‘privacy’ section below).

Geographic regions

Karonga district, northern Malawi (the Karonga Health and Demographic Surveillance Site)

Lilongwe, Central Malawi (Area 25 Research Site)

Key dates

• Data collection period in Karonga: 16 May 2013 - 18 April 2016
• Data collection period in Lilongwe: 03 June 2013 - 25 April 2017
• Data submitted for publication: 21 December 2018

Quality Controls

Data quality checks were carried out prospectively during data collection including range (plausibility) checks and restricted data entry and cross-checking between data tables to ensure all records were accounted for.

Species:

Human

Privacy:

One record is included for each individual, covering the period of the MEIRU NCD survey in 2013. Participant identifying information, including names, locations, and study codes have been scrambled or removed. ID numbers were scrambled using Nesstar Publisher and Statistical Disclosure Control methods described here (https://sdcpractice.readthedocs.io/en/latest/) were applied using sdcMicro software. Three SDC methods found in sdcMicro were applied to these data: Recoding, local suppression and Post Randomisation Method

Reducing detail in variables by recoding

In 3 variables agegroup5 (5 years age groups), cmarital (marital status) and educat (education level), the detail is reduced by recoding values. Table 1 gives an overview of the recorded variables

Table 2: Overview of recoded variables

Local suppression

We further anonymise the data by suppressing certain values. Values of the key variables considered to pause elevated risk of disclosure were deleted. Table 2 gives an overview of the number of suppressed values per variable.

Table 2 Overview of Suppressions

Post Randomisation Method

32 categorical variables in the data were considered to be spontaneous recognition variables meaning that they are variables that could potentially identify individuals without much searching. These variables are: 'drinker', 'smoker', 'agedibp_cat', 'agediab_cat', 'agechole_cat', 'ageathma_cat', 'agetb_cat', 'electric_mode', 'parlamp_mode', 'telv_mode', 'mopho_mode', 'landpho_mode', 'sofa_mode', 'refrig_mode', 'tabchar_mode', 'egcook_mode', 'watpipe_fmode', 'motcyc_mode', 'car_mode', 'bicyc_mode', 'radio_mode', 'cow_mode', 'oxcart_mode', 'hhwate_fmode', 'wheze', 'hhpossscore_mode', 'hhpossscorek_mode', 'hhpossscorel_mode'.

Local suppression was considered unsuitable for these variables since the information loss was going to be huge. Consequently a perturbative method called Post Randomisation Method (Templ, Meindl, & Kowarik, 2013) was used. This method alters some values of the selected variables according to some reclassification rules such that if an intruder attempts to re-identify individuals, they make matches but the match will be to a wrong individual.

Table 3: Overview of perturbed variables and the number of values changed using PRAM

Ethics

Ethics approval was obtained from LSHTM and the Malawi National Health Sciences Research Committee (NHSRC).

The ethics protocol numbers are: LSHTM #6303 and NHSRC #1072

Keywords

Cardiovascular diseases, diabetes, risk factors, Africa, Malawi

Language of written material

English

Project title

Understanding local determinants of cardiovascular disease and diabetes to inform novel interventional strategies

Principal Investigator

Current PI - Professor Mia Crampin

Former PIs’ Professor Moffat Nyirenda and Professor Shabbar Jaffar.

Funder/Sponsor

Wellcome Trust

Grant Number

098610/Z/12/Z

Data Creators

Associated Roles

File Description