JMP Clinical Basics | Distribution Reports | Understanding Count and Percent Calculations

Understanding Count and Percent Calculations
The percent calculations represent the count of subjects in a given demographic group experiencing a given event divided by the count of total subjects in that demographic group.
Algorithms
Count of subjects in demographic group (DMG) with event (AE)
where
S i is the i th subject,
X i = g ( S i . AE , DMG ), and
N = Subject number
Note : X i =1 if the i th subject Si is in the DMG (demographic group) and has an AE value on at least one occasion. If these conditions are not met, X i has a value of 0.
Count of subjects in demographic group (DMG)
where
S i is the i th subject,
Y i = g ( S i . DMG ), and
N = Subject number
Note : Y i =1 if the i th subject Si is in the DMG (demographic group). If not, Y i has a value of 0.
Percent of subjects in demographic group (DMG) experiencing event (AE)
These subject percentages are computed dynamically by the JMP Clinical distribution report results and enable you to interactively choose:
As you change the values of the Grouping and Stacking variables in the report, the structure and percent calculations of the graph and table are automatically updated. See the examples below:
Examples in AE Distribution Using Nicardipine Data (Treatment Emergent Events):
This study has 902 subjects in the safety analysis population with 455 on Placebo, 447 on NIC .15.
Example 1 : Using the Drill-downs on the Output dashboard, select None for Demographic Grouping and None for AE Stacking and examine the Counts Table tab.
407/902 = .451 45.1% of subjects experienced (treatment emergent) vasoconstriction
Example 2 : Using the Drill-downs on the Output dashboard, select Planned Treatment for Period 1 for Demographic Grouping and None for AE Stacking and examine the Counts Table tab. Note how the values change.
168/447 = .376 37.6% of subjects on NIC .15 experienced vasoconstriction
239/455 = .525 52.5% of subjects on Placebo experienced vasoconstriction
Example 3 : Using the Drill-downs on the Output dashboard, select Planned Treatment for Period 1 for Demographic Grouping and Severity/Intensity for AE Stacking and examine the Counts Table tab. Note how the values change.
80/447 = 17.9% of subjects on NIC .15 experienced MILD vasoconstriction
62/447 = 13.9% of subjects on NIC .15 experienced MODERATE vasoconstriction
26/447 = 5.8% of subjects on NIC .15 experienced SEVERE vasoconstriction
85/455= 18.7% of subjects on Placebo experienced MILD vasoconstriction
85/455= 18.5% of subjects on Placebo experienced MODERATE vasoconstriction
70/455= 15.4% of subjects on Placebo experienced SEVERE vasoconstriction
Note : In the example, the demographic group column changes the percent calculations (aka changes the value of the denominator used in the formula), while the stacking/categorization variable just partitions the counts and percentages.
The value of percent calculation comparison can be seen clearly in the two plots shown below. The first plot shows the AE Counts graph grouped by RACE and categorized by Serious Event .
This plot can be misleading because of the large differences in the respective number of subjects in each RACE category. In this case, comparing the percentages might be more informative.
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Click Show Percents (located above the plot and circled below).
The resulting plot (below) then is much more useful for making comparisons.
Percent Calculations When an Interactive Data Filter Is Applied.
When you use the Data Filter (located on the right side of the report) to filter the records that are shown, the change does NOT affect the demographic group denominator values that are used in the percent calculations. These denominators, as described previously, are derived in the SAS programming of the analysis based on the analysis population. The counts (the numerator in the percent formula) of subjects experiencing the event (and now meeting the data filter criteria) change values to reflect the use of the data filter.
In the following example, the default (Event Type = All) AE Distribution report was run for the Nicardipine sample data and the results were subsequently filtered for Serious Event = Y , as shown below:
The results are shown below:
88/455 = 19.3% of subjects on Placebo experienced serious vasoconstriction.
If the Data Filter selection is based on a demographic variable, care must be taken to interpret the results.
In the following example, Sex = F has been selected in the data filter:
Note : You must click Clear (circled above) to clear out prior filters before making a new selection.
The results are shown below:
206/455 = 45.3% of subjects on Placebo were females with vasoconstriction.
In this example, the 455 subjects on placebo make up the denominator of the percent calculation. The females showing vasoconstriction represent the subject count (or numerator) that had the event subject to any data filter specification (206 female subjects that had vasoconstriction).
Note : If you want to have such demographic filters reflected in the reference population, a pre-specified filter should be used up front, as described below.
Percent Calculations with a Dialog-Specified Subject Filter
When the JMP Clinical is performing an analysis with a subject filter, the value of the denominator changes to reflect the subjects that meet the criteria of the filter.
For example, on the AE Distribution dialog, you can:
Example 1 : Generate a Subject Filter of only females:
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Run DM Distribution Report.
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Select F category in SEX distribution bar chart (or from the data filter). Note how the females are highlighted in all of the distributions.
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Click the Create Subject Filter Drill Down button (circled above).
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Specify this filter as a Subject Filter in the AE Distribution dialog
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Click Run .
Example 2: Specify an Additional Filter to Include Subjects
When filtering is applied up front , the percent values and their interpretation are based on females only:
There are 297 females on Placebo.
206/297 = 69.4% of female subjects on Placebo experienced Vasoconstriction.
In this example, the 297 female subjects on placebo make up the denominator of the percent calculation. The females showing vasoconstriction represent the subject count (or numerator) that had the event (206 female subjects that had vasoconstriction). In this case, where filtering is applied BEFORE the analysis, the percent calculation (206/297 = 69.4%) represents the number of females showing vasoconstriction out of FEMALE subjects only on Placebo.
In the example described above, the 455 subjects (male and female) on placebo make up the denominator of the percent calculation. The females s represent the subject count (or numerator) that had the event subject to any data filter specification (206 female subjects that had vasoconstriction). In this case, where filtering is applied AFTER the analysis, the percent calculation (206/455 = 45.3%) represents the number of females showing vasoconstriction out of ALL subjects (not just females) on Placebo.
Percent Calculations in Other JMP Clinical Distribution Reports
The examples described, while highlighting the AE Distribution report heavily, also reflect the analyses performed by the other events/interventions distributions.
For example, if you run the AE Distribution report using the Nicardipine example that is shipped with JMP Clinical and select Serious Event using the AE Stacking drill-down, you see the following Counts Table .
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Click Related CM , as shown below.
JMP Clinical runs the concomitant medications Interventions Distribution report for the 43 selected subjects.
If you click Show Percentages on the dashboard, you see the Counts Graph and Counts Table shown below:
In this example, 30/43 = 69.8% of subjects on NIC .15 who experienced Vasoconstriction were given Acetaminophen.
These examples should highlight the extreme flexibility of the JMP Clinical system to understand events and interventions occurrence to answer a wide variety of clinically relevant questions.