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Title: Distribution of Alanine Aminotransferase (ALT) by Time and Treatment

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Title Distribution of Alanine Aminotransferase (ALT) by Time and Treatment
Graph_Subgroup Labs Liver
Labs_Liver_Clinical_Question
Baseline: 2. Is there a temporal relationship between treatment and lab value?,
Baseline: 3. What are the toxicity grade trends over time?
Description This is a box plot of the laboratory parameter, alanine aminotransferase (ALT) by treatment group over the time course of a trial. The x-axis represents the study week and it is important that the axis scale be uniformly separated (for instance in this graphic the Weeks are accurately separated). The y-axis represents the ALT divided by the upper limit of normal (ULN). Upper limit of normal is calculated by dividing the standard result ( SDTM dataset variable lbstresn) in numeric units by the standard high range limit (SDTM dataset variable lbstnrhi). Original units can be substituted if needed as the upper limit of normal is normalized (has no units). A value of ‘2’ is interpreted as the ALT result being 3 times the ULN value. Clinical concern level is customarily considered above 2, however this would be defined by the individual team.

Above the reference line of 2 are numbers representing the frequency of subjects within each treatment whose ALT level was above 2xULN. Depending on the areas of interest or what may be deemed as clinically significant, the y-axis range should be alered accordingly.
Below the graphic are both a legend indicating the treatment groups depicted on the graph and a legend indicating the at risk subject population by treatment group at each specific visit. Note that due to the uniform axis separation, and the visit schedule of the study, there may be blanks if there is no data for a specific visit. It is important to consider that if a color graphic is not presented, the line styles will allow for distinction between treatment groups.

*NOTE: A later release of SAS version 9.2 is necessary to accurately utilize the ‘discreteoffset’ option within the code. This option allows for the box plots at each visit to be offset horizontally from each other and not overlaid. The included graph above does not utilize this option, rather it offsets the box plots by creating an additional Week variable as seen in the code. Later versions of SAS also allow for more advanced label editing, thereby allowing the programmer to choose a symbol for the legend.

Contributor/Email Robert Gordon (rgordon2@its.jnj.com)
Additional_Contributor_Info Code based upon output and code created by the SAS Institute on the following website: http://support.sas.com/kb/39/080.html
Background This graphic was taken from the above SAS Institute site. Only minor adaptations were made (title, footnote, graph sizing).
Keywords Boxplot, LFT
References http://support.sas.com/kb/39/080.html
Datasets Other
CDISC_Data

Data_Format Data set(s) necessary for the graphic are created within the code. Note the format of the data set as similar format would need to be utilized in other data sets prepared for use with this code.
CLASSIFICATIONS

Graph_Type Boxplot
Variable_Relationship Continuous versus Continuous
Data_Types Continuous
Special_Considerations Depending on the lab parameter and the level of concern, clinically meaningful values (e.g. > 2 times upper limit of normal) and interpretation will differ. It is important to specify these values and properly incorporate them into the code before producing a graphic for interpretation.
Code_Available Yes
Software Program SAS
Software

R-Code - Attachment

R-Code

SAS-Code - Attachment Gordon - Distribution ALT - SAS Code
Stata-Code - Attachment

Stata-Code

Other Code - Attachment

Other Code

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Reference Image Gordon_Distribution_ALT_200.png
Topic revision: r1 - 02 May 2012 - 13:28:18 - MaryBanach
 

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