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Data Specifications Didactics on development of a concept sheet EA IeDEA Meeting May 16-17, 2011 Beverly Musick

Data Specifications Didactics on development of a concept sheet EA IeDEA Meeting May 16-17, 2011 Beverly Musick

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Data Specifications

Didactics on development of a concept sheet

EA IeDEA MeetingMay 16-17, 2011

Beverly Musick

Introduction

• Data specification needs• Proposal from data management point of view• Lessons learned

Data Specification Needs

• Each concept proposal must− Clearly define the cohort of patients to be

included (ex. HIV-positive children enrolled prior to 1 year of age)

− Identify the variables needed (site-level, patient-level, collected elements, and derived variables)

− Specify the range/scope of encounters required (ex. pre-ART, post-ART)

Targeted Cohort

• Cohort definition is not always straight forward• Provide as much detail as possible• Include age ranges even if studying only adults

− Sites have different cut-off ages for defining adults

• Specify the point in time (enrollment, ART initiation, etc.) that should be used to define age or other variables for eligibility

• Complex selection criteria may need input from biostatistician (eg. random sampling, matching)

Targeted Cohort• Questions to consider:

− If a cohort is to include only HIV-positive children, how will HIV status be defined? What variables will be used to identify these children?

− How will pregnant women impact the aims and analyses? Consider body weight, ARVs, gestation.

− Should initiation of triple-drug therapy for PMTCT be treated differently than initiation of therapeutic ART?

− Is a comparison (control) group needed? If so, how will such patients be selected/identified?

Collected Elements

• Raw data from the data collection forms• Simple observational data• Examples

− Sex− Date of birth− WHO stage

• Most of the variables in the IeDEA Minimum Datasets are collected elements

Derived Variables

• A derived variable is one that must be calculated from data elements available in the minimum dataset such as− Age at ART start− Time to first AIDS-defining event− ART eligibility

• Concept proposal must include the data elements needed and the instructions to derive these additional variables

Range of Encounters• Questions to consider

− If studying HIV-exposed children, should you include visit data after definitive test has identified the child as HIV-negative (or positive)?

− If studying characteristics that prompt initiation of ART, do you need any visit data post ART?

− Many variables are only collected at the enrollment visit even though they can change over time (i.e. marital status, HIV disclosure). Do you need to included the enrollment visit and should there be a restriction on length of time between enrollment and event being studied.

Data management point of view

• Close review of the aims and hypotheses is needed to ensure that they clearly reflect available IeDEA data− SOP for Data Quality and Transfer Version 2.0 contains

the patient-level minimum datasets available− IeDEA Site Assessment Tool which includes the

Pediatric Site Assessment Survey contains site-level data available

• Ensure that all variables identified in the aims and analysis sections are listed in the Variables Required sections− If mortality is an endpoint then death and date of death

must be in the variables list

Data management point of view

• If using items from the IeDEA Site Assessment Tool, please include the item number in the Site-Level Variables Required section on the Concept Proposal form

• Also include any instructions regarding manipulation of compound items.

Lessons Learned

• There are a few variables that are essential to almost every proposal

− Date of birth

− Date of enrollment into care

− Date of initiation of ART

− Sex

− CD4 at ART initiation

• Without these variables a patient and sometimes an entire site must be excluded from the analysis cohort

Lessons Learned

• Distinction between therapeutic ART and PMTCT ART is crucial− Need accurate pregnancy and ART start-stop

dates and reasons• Accurate and detailed documentation of anti-TB

treatment is lacking at many sites• Analysis of some variables requires inclusion and

adjustment of other variables