Treatment Arms

Overview

In a clinical trial, patients are divided into groups that each receive a different treatment or a placebo. These groups are called treatment arms. In Step 5 of the wizard, you define your trial's treatment arms, set how patients are divided between them, configure each arm's visit schedule, and assign kits to each visit.

Treatment arm configuration feeds directly into cohort management in Step 6 and ultimately drives the demand forecasting engine.

Example: A trial enrolling 150 patients that compares Drug A against a placebo might have:

• Arm 1 — "Drug A": 60% of patients (90 patients) receive the active treatment
• Arm 2 — "Placebo": 40% of patients (60 patients) receive the placebo

Each patient follows a visit schedule specific to their arm and receives the appropriate kits at each visit. Different arms can have different visit frequencies, different kits, and different drop-out rates — all of which affect how many kits your trial needs.

Prerequisites

Before configuring treatment arms, you must have at least one kit defined in Step 3 (Trial Kits). If no kits exist, the step displays a prompt directing you back to Step 3, and the Continue button remains disabled.

Creating Treatment Arms

Click the + button in the tab bar to add a new treatment arm. Each arm is created with these defaults:

• Name: Empty (required)
• Allocation percentage: 0%
• Number of visits: 1
• Interval type: Consistent
• Drop-out rate type: Global (10%)

Treatment Arm Name

• Required. Enter a clear, descriptive name (e.g., "Drug A", "Placebo", "High Dose 100mg").
• The name appears throughout the forecasting results, so choose something distinct and recognizable.

Allocation Percentage

• Required. Enter the percentage of patients randomized to this arm (0.1% to 100%).
• All arms' percentages must sum to exactly 100%.
• A Participant Distribution card at the top of the form shows a live progress bar:
  • Green when the total equals 100%
  • Amber when the total is under 100%
  • Red when the total exceeds 100%

Visit Schedule Configuration

Each treatment arm has its own visit schedule — the number of times patients return and how those visits are spaced over time.

Number of Visits

• Enter the total number of visits for this arm (minimum: 1).
• Typical trials range from 3 to 20 visits, though hundreds are supported.
• More visits means more kits per patient, which increases total kit demand.

Visit Interval Type

Choose between two modes for spacing visits:

Consistent Intervals — All visits are equally spaced.

• Select the Consistent radio option.
• Configure the interval by entering a number and selecting a time unit (Days, Weeks, Months, or Years).
• Example: 4 visits every 2 weeks produces Visit 1 at enrollment, Visit 2 at Week 2, Visit 3 at Week 4, Visit 4 at Week 6.

Custom Intervals — Each visit can have a different interval from the previous visit.

• Select the Custom radio option.
• A table appears with one row per visit containing the visit number, days from previous visit, and time unit.
• Visit 1 is locked to Day 0 (the screening visit) and cannot be edited or deleted.
• Use the Add Interval button and the delete icon on each row to manage visits.
• Example: Visit 1 at Day 0, Visit 2 at Day 7 (intensive early phase), Visit 3 at Day 90 (long follow-up).

Note: When you switch from Consistent to Custom mode, existing kit assignments are cleared and the custom interval table is pre-populated with weekly intervals. You will need to reassign kits.

Interval Comparison

Kit Assignment

After configuring visits, you assign kits to the arm. How this works depends on your interval type.

Consistent Intervals: Kit Selection Table

A Treatment Kits table appears with one row per kit from Step 3:

• Use the + and - buttons to adjust the quantity per visit (minimum: 1).
• At least one kit must be included for the arm to be valid.
• Demand impact: Total kits = Quantity per visit x Number of visits x Number of patients in this arm.

Custom Intervals: Per-Visit Kit Assignment

In custom mode, kits are assigned per visit rather than uniformly. Each row in the custom interval table has a Select Kits button (or Edit Kits (N) if kits are already assigned).

Clicking this button opens a modal with Include/Exclude toggles and quantity steppers, scoped to that specific visit:

• Every visit must have at least one kit assigned.
• Different visits can have different kits and quantities.
• Example: Visit 1 gets a "Starter Kit" and a "Lab Kit." Visit 2 gets only the "Drug A Kit" with quantity 2.

Drop-Out Rate Configuration

Drop-out rates model the percentage of patients who discontinue the trial before completing all visits. This directly reduces kit demand for later visits, making your forecast more realistic.

Drop-Out Rate Type

Global (Single Rate) — One drop-out rate applied uniformly across all visits.

• Enter a percentage (0 to 100%). Default: 10%.
• Example: With 100 enrolled patients and a 10% global drop-out rate, the system reduces the expected patient count at later visits accordingly.

Per Visit — A different drop-out rate at each visit checkpoint.

• In Consistent interval mode: enter a single per-visit drop-out rate (e.g., 5%) applied at each visit. Default: 5%.
• In Custom interval mode: a Drop-out Rate (%) column appears in the custom interval table. Enter a rate (0 to 100%) for each visit individually.

Drop-Out Impact on Demand

Drop-out rates compound across visits. Starting with 100 patients and a 5% per-visit drop-out rate:

This cascading reduction is reflected in the demand forecasting engine, producing more accurate kit requirements.

Copy Configuration Between Arms

When you have two or more treatment arms, a Copy to... button appears in each arm's header. This lets you duplicate one arm's entire configuration to other arms.

1. Click Copy to... on the source arm.
2. A dialog appears listing all other arms. Select one or more target arms.
3. Click Copy Configuration to Selected (N).
4. The system copies the visit schedule, interval settings, kit assignments, and drop-out configuration to each selected arm.
5. Each target arm keeps its own name and allocation percentage — only the schedule and kit configuration are overwritten.

This is useful when multiple arms share similar visit schedules. Copy the configuration from one arm, then make small adjustments on the targets.

Managing Multiple Arms (Tabbed Interface)

Each treatment arm appears as a tab at the top of the form. The tab bar shows:

• Arm name (or "Arm N" if unnamed)
• Allocation percentage as a small badge (e.g., "60%")
• A red dot indicator if the arm has validation errors
• An x button to delete the arm (with confirmation dialog)

Click a tab to switch between arms, click + to add a new arm, or click x to delete an arm. Tabs scroll horizontally if you have many arms.

Validation Before Proceeding

The Continue button to Step 6 remains disabled until all of the following are satisfied:

A validation summary banner appears at the top of the form listing all outstanding issues with the specific arm and field that needs attention.

Tips

• Start simple. Begin with a straightforward two-arm trial (Drug vs. Placebo) using consistent visit intervals. You can add complexity in Step 6.
• Watch the allocation bar. All arm percentages must sum to exactly 100%. The real-time progress bar makes this easy to track.
• More visits = more kits. Consider whether your supply chain can support the visit frequency you are configuring.
• Assign kits to every visit. In custom interval mode, each visit needs at least one kit. Blank assignments block you from proceeding.
• Use "Copy to..." for similar arms. Copy the configuration from one arm and adjust only what differs. This saves significant data entry.
• Drop-out rates are optional but valuable. Industry standard drop-out rates are typically 5 to 15%. Even a rough estimate improves forecast accuracy.
• Switching interval types clears kit assignments. Configure your interval type first, then assign kits.