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Title: Lab Parameter Shift Plots, Baseline vs. Study

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Title Lab Parameter Shift Plots, Baseline vs. Study
Graph_Subgroup Labs Liver
Labs_Liver_Clinical_Question Baseline: 1. What are the changed and percent changes from baseline over time? ie are abnormal labl values a result of abnormal baseline or have values changed on study?
Description This figure compares each patient’s baseline value to their on-study or post-baseline lab values at all time points. The lower x-axis represents the baseline ‘times upper limit of normal’ (xuln)for the parameters graphed where a value of 1 would mean that the result was normal. Any value above or below 1 would be considered above the upper limit of normal or below the upper limit of normal respectively. For instance, a value of 3 would be read as ‘3 times the upper limit of normal’. Upper limit of normal is calculated by dividing the standard result (lbstresn) in numeric units by the standard high range limit (lbstnrhi). Original units can be substituted if needed as the upper limit of normal is normalized (has no units). There are reference lines that separate the upper limit of normal values. The labels on the top section (lab test name) panel the chart by the different lab tests. The y-axis are the on-study or post-baseline xuln values. It is important to note that similar scale for the xuln axes (both x and y) should be maintained, making each panel a square. The square shape is maintained by specifying the width and height of the figure in the programming code.

This is similar to the LFT Safety Panel plot in that it too is a scatter plot of lab parameters. However, this is a 1x2 panel scatter plot that is run by a macro where the user enters only 2 lab test names. In addition, this plots baseline upper limit of normal against all on study values while the LFT Safety Panel plots baseline against maximum value.

One of the main interpretations of this graphic is to determine if a patient’s lab values have increased or decreased since baseline. The 45 degree reference line is included for ease of interpretation. An increase in lab parameter would be represented by any point above the 45 degree line. The farther the point moves toward the upper left quadrant, the larger the increase from baseline. Likewise, the farther the point moves below the reference line and towards the lower right quadrant, the large the decrease from baseline.
Contributor/Email Robert Gordon (rgordon2@its.jnj.com)
Additional_Contributor_Info Original code provided by Susan Schwartz from the SAS Institute
Background This graphic was inspired from output and code originally created by Susan Schwartz at the SAS Institute and included in the following article. Schwartz, Susan. 2009 “Clinical Trial Reporting Using SAS/GRAPH® SG Procedures.” Proceedings of the SAS Global Forum 2009 Conference. Cary, NC: SAS Institute Inc. Available at http://support.sas.com/resources/papers/proceedings09/174-2009.pdf
Keywords Scatter plot, Panel, Baseline
References http://support.sas.com/resources/papers/proceedings09/174-2009.pdf
Datasets

CDISC_Data ADLBC
Data_Format

CLASSIFICATIONS

Graph_Type Scatterplot
Variable_Relationship Continuous versus Continuous
Data_Types Continuous
Special_Considerations Depending on the lab parameter and the level of concern, reference ranges 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 SAS V9.2
R-Code - Attachment

R-Code

SAS-Code - Attachment Gordon - Lab Shift Parameters - SAS - Doc
Stata-Code - Attachment

Stata-Code

Other Code - Attachment

Other Code

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Reference Image Gordon_Shift_Plot_200.png
Topic revision: r5 - 02 May 2012 - 13:33:14 - MaryBanach
 

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