Quasi experimental designs in pharmacist intervention research

Area of Science:

• Pharmacist Intervention Research
• Health Services Research
• Evidence-Based Practice

Background:

• Randomization in pharmacist intervention studies is often challenging.
• Quasi-experimental designs provide alternatives when true experimental models are not feasible.
• These designs include non-randomized and sometimes non-controlled approaches.

Purpose of the Study:

• To overview quasi-experimental designs.
• To discuss their strengths and weaknesses.
• To investigate their application in pharmacist intervention research over the past decade.

Main Methods:

• Literature review of quasi-experimental designs.
• Classification of designs into five categories.
• Analysis of their application in pharmacist intervention research.

Main Results:

• Quasi-experimental designs include those without control groups, with control groups (with or without pre-tests), interrupted time series, and stepped wedge designs.
• One-group pre-post-test and non-equivalent control group designs are most common in pharmacist intervention research.
• These designs have been used to evaluate pharmacist interventions in medication management and specific diseases.

Conclusions:

• Quasi-experimental studies are useful for proof of concept and pilot testing of complex pharmacist interventions.
• While yielding weaker evidence of clinical efficacy individually, collectively they build evidence for pharmacist interventions.
• Researchers should use more robust quasi-experimental designs when randomized controlled trials are not feasible due to logistical or ethical reasons.