RCTs are near the top of the evidence hierarchy because they provide strong evidence about treatment effectiveness and causal relationships. Only systematic reviews and meta-analyses of multiple high-quality RCTs are generally considered stronger evidence.

1. Was the study well-designed? Was the methodology appropriate? Was randomisation done properly? Were the right people included? This checks whether the study was set up in a way that could actually answer the research question.

2. Can we trust the results? Were there any biases? Were participants followed up properly? Were the outcomes measured consistently? This checks whether the findings are valid and reliable.

3. Is it relevant to real-life practice? Can the results be applied to your specific patient or population? Are the benefits worth the risks? This connects the research to the real world — for example, to Mr. Ahmed's case.

• Intervention group – receives the new treatment, service, or program.

• Control group – receives a placebo, usual care, or no intervention.

Randomization minimizes bias, making RCTs the gold standard for evaluating causality.

2. Use in Health Care

RCTs are common in medicine, nursing, public health, and clinical services.

Examples:

• Testing a new drug against a placebo.

• Comparing two types of physiotherapy for back pain.

• Evaluating whether nurse-led follow-up reduces hospital readmissions.

Key strength:

Provides strong evidence that the intervention causes the observed effect.