Storing Results Storing Results DataData

Clement McDonald, M.D.Clement McDonald, M.D.Director, Lister Hill Center National Center for Biomedical Director, Lister Hill Center National Center for Biomedical

CommunicationsCommunicationsNational Library of MedicineNational Library of Medicine

February 11, 2008February 11, 2008

Scope Scope

The focus is on summary data of The focus is on summary data of the kind one sees in publication the kind one sees in publication

Characteristics of patients at base Characteristics of patients at base lineline

Differences between the outcomes Differences between the outcomes of the various study armsof the various study arms

Not patient level data Not patient level data

GoalsGoals

Represent this data in a generalized Represent this data in a generalized but “structured” formatbut “structured” format

Take advantage of what is in the Take advantage of what is in the registry data base to ease entry of registry data base to ease entry of results dataresults data

Minimize entry workMinimize entry work Accommodate most study designsAccommodate most study designs

Three parts to the Three parts to the problem problem Define the variables - used in the Define the variables - used in the

study study To characterize populationTo characterize population To measure outcomes To measure outcomes Etc.Etc.

– E.g. Age, creatinine, PHQ-9 E.g. Age, creatinine, PHQ-9

For each variable For each variable

Name Name Description Description Data type (e.g. continuous, Data type (e.g. continuous,

categorical, time to event )categorical, time to event ) Additional information depending Additional information depending

upon data type e.g.:upon data type e.g.:– For categorical variables - the categoriesFor categorical variables - the categories– For continuous variables- the units of For continuous variables- the units of

measuremeasure

Define the study arms Define the study arms and phases. and phases. Name Name Description Description E.g.E.g.

– Arm 1 - treat with new drug or device Arm 1 - treat with new drug or device XX

– Arm 2 - placeboArm 2 - placebo Statistical analyses – as Statistical analyses – as

descriptive text. descriptive text.

Define tablesDefine tables

Rows variables Rows variables Columns study arm phase - and one Columns study arm phase - and one

column for statistical analysis. column for statistical analysis. List the discrete summary observations List the discrete summary observations

per cell depends on data type per cell depends on data type – E.g. for continuousE.g. for continuous

NN MeanMean Coefficient of variationCoefficient of variation (more)(more)

Data structuresData structures

XML for current testing phaseXML for current testing phase

As relational data base As relational data base - simplest incarnation - simplest incarnation Table for study – with record per study Table for study – with record per study Table for variables - one record per Table for variables - one record per

variablevariable Table for study arms/phases - one Table for study arms/phases - one

record per study arm phaserecord per study arm phase Table for overview of each tables – one Table for overview of each tables – one

record per cell record per cell Table to define each table - one record Table to define each table - one record

per cellper cell

Non trivial problemNon trivial problem

Especially for newer study Especially for newer study designsdesigns