What does “Primary Purpose: Treatment” mean in a clinical study?

Question

At clinicaltrials.gov you can look up studies to learn more about them. On one such study, I saw this block of text:

Study Type: Interventional 
Study Design: Allocation: Randomized
              Intervention Model: Parallel Assignment
              Masking: Participant, Care Provider, Investigator, Outcomes Assessor
              Primary Purpose: Treatment

I understand all of these except the last one. To the untrained eye, that sounds like "we mostly want to treat people, but we will gather data while we're doing so." Is that a correct interpretation? What are other possible responses to "Primary Purpose" and how would they differ from "Treatment"?

Answer 1

Your interpretation is basically correct.

The formal definition is:

https://prsinfo.clinicaltrials.gov/definitions.html#IntPurpose

Primary Purpose *§ Definition: The main objective of the intervention(s) being evaluated by the clinical trial. Select one.

• Treatment: One or more interventions are being evaluated for treating a disease, syndrome, or condition.

The other choices are:

• Prevention: One or more interventions are being assessed for preventing the development of a specific disease or health condition.

• Diagnostic: One or more interventions are being evaluated for identifying a disease or health condition.

• Supportive Care: One or more interventions are evaluated for maximizing comfort, minimizing side effects, or mitigating against a decline in the participant's health or function.

• Screening: One or more interventions are assessed or examined for identifying a condition, or risk factors for a condition, in people who are not yet known to have the condition or risk factor.

• Health Services Research: One or more interventions for evaluating the delivery, processes, management, organization, or financing of healthcare.

• Basic Science: One or more interventions for examining the basic mechanism of action (for example, physiology or biomechanics of an intervention).

• Device Feasibility: An intervention of a device product is being evaluated in a small clinical trial (generally fewer than 10 participants) to determine the feasibility of the product; or a clinical trial to test a prototype device for feasibility and not health outcomes. Such studies are conducted to confirm the design and operating specifications of a device before beginning a full clinical trial.

• Other: None of the other options applies.