Understanding Different Types of Clinical Trials

When we talk about clinical trials, we often hear terms like “randomised” or “double-blind,” but what do these mean — and how strong is the evidence they produce?

Here’s a brief guide:

1. Observational Study

• Researchers observe patients without changing treatments.
• Example: watching CPA patients on current antifungals to track outcomes.
• Power: Weak to moderate — shows correlation but not cause.

2. Open-Label Trial

• Everyone knows which treatment they’re getting.
• Useful for testing safety or feasibility.
• Power: Moderate — can be biased, but still useful.

3. Randomised Controlled Trial (RCT)

• Participants are randomly assigned to one treatment or another.
• Helps ensure fairness and balance between groups.
• Power: Strong — considered the gold standard for testing effectiveness.

4. Double-Blind RCT

• Neither patient nor doctor knows who is getting the real treatment or the control.
• Reduces bias even further.
• Power: Very strong — this is the highest standard for reliable evidence.

5. Feasibility or Pilot Trial

• A smaller version of a full RCT, used to test if a larger trial is possible.
• Checks things like recruitment, adherence, and side effects.
• Power: Lower for proving treatment works, but crucial for planning a full trial