2 Disposition of Participants Table

2.1 Overview

Clinical trials needs to track how participants flow through a study from enrollment to completion. Following ICH E3 guidance, regulatory submissions require a disposition table in Section 10.1 that summarizes:

Enrolled: Total participants who entered the study
Completed: Participants who finished the study protocol
Discontinued: Participants who left early and their reasons

This tutorial shows you how to create a regulatory-compliant disposition table using Python’s rtflite package.

import polars as pl # Manipulate data
import rtflite as rtf # Reporting in RTF format

2.2 Step 1: Load Data

We start by loading the Subject-level Analysis Dataset (ADSL), which contains all participant information needed for our disposition table.

The ADSL dataset stores participant-level information including treatment assignments and study completion status. We’re using the parquet format for data storage.

adsl = pl.read_parquet("data/adsl.parquet")

Let’s examine the key variables we’ll use to build our disposition table:

USUBJID: Unique identifier for each participant
TRT01P: Treatment name (text)
TRT01PN: Treatment group (numeric code)
DISCONFL: Flag indicating if participant discontinued (Y/N)
DCREASCD: Specific reason for discontinuation

adsl.select(["USUBJID", "TRT01P", "TRT01PN", "DISCONFL", "DCREASCD"])

shape: (254, 5)

USUBJID	TRT01P	TRT01PN	DISCONFL	DCREASCD
str	str	i64	str	str
"01-701-1015"	"Placebo"	0	""	"Completed"
"01-701-1023"	"Placebo"	0	"Y"	"Adverse Event"
"01-701-1028"	"Xanomeline High Dose"	81	""	"Completed"
"01-701-1033"	"Xanomeline Low Dose"	54	"Y"	"Sponsor Decision"
"01-701-1034"	"Xanomeline High Dose"	81	""	"Completed"
…	…	…	…	…
"01-718-1254"	"Xanomeline Low Dose"	54	""	"Completed"
"01-718-1328"	"Xanomeline High Dose"	81	"Y"	"Withdrew Consent"
"01-718-1355"	"Placebo"	0	""	"Completed"
"01-718-1371"	"Xanomeline High Dose"	81	"Y"	"Adverse Event"
"01-718-1427"	"Xanomeline High Dose"	81	"Y"	"Lack of Efficacy"

2.3 Step 2: Count Total Participants

First, we count how many participants were enrolled in each treatment group.

We group participants by treatment arm and count them using .group_by() and .agg(). The .pivot() operation reshapes our data from long format (rows for each treatment) to wide format (columns for each treatment), which matches the standard disposition table layout.

n_rand = (
    adsl
    .group_by("TRT01PN")
    .agg(n = pl.len())
    .with_columns([
        pl.lit("Participants in population").alias("row"),
        pl.lit(None, dtype=pl.Float64).alias("pct") # Placeholder for percentage (not applicable for totals)
    ])
    .pivot(
        index="row",
        on="TRT01PN",
        values=["n", "pct"],
        sort_columns=True
    )
)

n_rand

shape: (1, 7)

row	n_0	n_54	n_81	pct_0	pct_54	pct_81
str	u32	u32	u32	f64	f64	f64
"Participants in population"	86	84	84	null	null	null

2.4 Step 3: Count Completed Participants

Next, we identify participants who successfully completed the study and calculate what percentage they represent of each treatment group.

We filter for participants where DCREASCD == "Completed", then calculate both counts and percentages. The .join() operation brings in the total count for each treatment group so we can compute percentages.

n_complete = (
    adsl
    .filter(pl.col("DCREASCD") == "Completed")
    .group_by("TRT01PN")
    .agg(n = pl.len())
    .join(
        adsl.group_by("TRT01PN").agg(total = pl.len()),
        on="TRT01PN"
    )
    .with_columns([
        pl.lit("Completed").alias("row"),
        (100.0 * pl.col("n") / pl.col("total")).round(1).alias("pct")
    ])
    .pivot(
        index="row",
        on="TRT01PN",
        values=["n", "pct"],
        sort_columns=True
    )
)

n_complete

shape: (1, 7)

row	n_0	n_54	n_81	pct_0	pct_54	pct_81
str	u32	u32	u32	f64	f64	f64
"Completed"	58	25	27	67.4	29.8	32.1

2.5 Step 4: Count Discontinued Participants

Now we count participants who left the study early, regardless of their specific reason.

We filter for participants where the discontinuation flag DISCONFL == "Y", then follow the same pattern of counting and calculating percentages within each treatment group.

n_disc = (
    adsl
    .filter(pl.col("DISCONFL") == "Y")
    .group_by("TRT01PN")
    .agg(n = pl.len())
    .join(
        adsl.group_by("TRT01PN").agg(total = pl.len()),
        on="TRT01PN"
    )
    .with_columns([
        pl.lit("Discontinued").alias("row"),
        (100.0 * pl.col("n") / pl.col("total")).round(1).alias("pct")
    ])
    .pivot(
        index="row",
        on="TRT01PN",
        values=["n", "pct"],
        sort_columns=True
    )
)

n_disc

shape: (1, 7)

row	n_0	n_54	n_81	pct_0	pct_54	pct_81
str	u32	u32	u32	f64	f64	f64
"Discontinued"	28	59	57	32.6	70.2	67.9

2.6 Step 5: Break Down Discontinuation Reasons

For regulatory reporting, we need to show the specific reasons why participants discontinued.

We filter out completed participants, then group by both treatment and discontinuation reason. The indentation (four spaces) in the row labels helps show these are subcategories under “Discontinued”. We also use .fill_null(0) to handle cases where certain discontinuation reasons don’t occur in all treatment groups.

n_reason = (
    adsl
    .filter(pl.col("DCREASCD") != "Completed")
    .group_by(["TRT01PN", "DCREASCD"])
    .agg(n = pl.len())
    .join(
        adsl.group_by("TRT01PN").agg(total = pl.len()),
        on="TRT01PN"
    )
    .with_columns([
        pl.concat_str([pl.lit("    "), pl.col("DCREASCD")]).alias("row"),
        (100.0 * pl.col("n") / pl.col("total")).round(1).alias("pct")
    ])
    .pivot(
        index="row",
        on="TRT01PN",
        values=["n", "pct"],
        sort_columns=True
    )
    .with_columns([
        pl.col(["n_0", "n_54", "n_81"]).fill_null(0),
        pl.col(["pct_0", "pct_54", "pct_81"]).fill_null(0.0)
    ])
    .sort("row")
)

n_reason

shape: (9, 7)

row	n_0	n_54	n_81	pct_0	pct_54	pct_81
str	u32	u32	u32	f64	f64	f64
" Adverse Event"	8	44	40	9.3	52.4	47.6
" Death"	2	1	0	2.3	1.2	0.0
" I/E Not Met"	1	0	2	1.2	0.0	2.4
" Lack of Efficacy"	3	0	1	3.5	0.0	1.2
" Lost to Follow-up"	1	1	0	1.2	1.2	0.0
" Physician Decision"	1	0	2	1.2	0.0	2.4
" Protocol Violation"	1	1	1	1.2	1.2	1.2
" Sponsor Decision"	2	2	3	2.3	2.4	3.6
" Withdrew Consent"	9	10	8	10.5	11.9	9.5

2.7 Step 6: Combine All Results

Now we stack all our individual summaries together to create the complete disposition table.

Using pl.concat(), we combine the enrollment counts, completion counts, discontinuation counts, and detailed discontinuation reasons into a single table that flows logically from top to bottom.

tbl_disp = pl.concat([
    n_rand,
    n_complete,
    n_disc,
    n_reason
])

tbl_disp

shape: (12, 7)

row	n_0	n_54	n_81	pct_0	pct_54	pct_81
str	u32	u32	u32	f64	f64	f64
"Participants in population"	86	84	84	null	null	null
"Completed"	58	25	27	67.4	29.8	32.1
"Discontinued"	28	59	57	32.6	70.2	67.9
" Adverse Event"	8	44	40	9.3	52.4	47.6
" Death"	2	1	0	2.3	1.2	0.0
…	…	…	…	…	…	…
" Lost to Follow-up"	1	1	0	1.2	1.2	0.0
" Physician Decision"	1	0	2	1.2	0.0	2.4
" Protocol Violation"	1	1	1	1.2	1.2	1.2
" Sponsor Decision"	2	2	3	2.3	2.4	3.6
" Withdrew Consent"	9	10	8	10.5	11.9	9.5

2.8 Step 7: Generate Publication-Ready Output

Finally, we format our table in RTF format using the rtflite package.

The RTFDocument class handles the complex formatting required for clinical reports, including proper column headers, borders, and spacing. The resulting RTF file can be directly included in regulatory submissions or converted to PDF for review.

doc_disp = rtf.RTFDocument(
    df=tbl_disp.select("row", "n_0", "pct_0", "n_54", "pct_54", "n_81", "pct_81"),
    rtf_title=rtf.RTFTitle(text=["Disposition of Participants"]),
    rtf_column_header=[
        rtf.RTFColumnHeader(
            text=["", "Placebo", "Xanomeline Low Dose", "Xanomeline High Dose"],
            col_rel_width=[3] + [2] * 3,
            text_justification=["l"] + ["c"] * 3,
        ),
        rtf.RTFColumnHeader(
            text=["", "n", "(%)", "n", "(%)", "n", "(%)"],
            col_rel_width=[3] + [1] * 6,
            text_justification=["l"] + ["c"] * 6,
            border_top=[""] + ["single"] * 6,
            border_left=["single"] + ["single", ""] * 3
        )
    ],
    rtf_body=rtf.RTFBody(
        col_rel_width=[3] + [1] * 6,
        text_justification=["l"] + ["c"] * 6,
        border_left=["single"] + ["single", ""] * 3
    ),
    rtf_source=rtf.RTFSource(text=["Source: ADSL dataset"]) # Required source attribution
)

doc_disp.write_rtf("rtf/tlf_disposition.rtf")  # Save as RTF for submission

rtf/tlf_disposition.rtf