Observational designs in clinical multiple sclerosis research: Particulars, practices and potentialities

Area of Science:

• Epidemiology
• Clinical Research Methodology

Background:

• Observational studies are crucial in multiple sclerosis (MS) research for discovery and hypothesis generation.
• Challenges exist in establishing causality due to confounding factors like indication bias, comorbidities, and socio-economic status.

Purpose of the Study:

• To provide an overview of diverse observational study designs and their applications in clinical research.
• To discuss the strengths and limitations of different observational designs in MS research.
• To propose improvements for reporting observational study findings.

Main Methods:

• Review of various observational study designs including cross-sectional, longitudinal, prospective, retrospective, case reports, case series, ecological studies, cohort studies, and case-control studies.
• Discussion of randomized controlled trial (RCT)-extension studies and patient registries.
• Exploration of phase 1 and phase 4 observational studies in pharmacotherapeutic research.

Main Results:

• Observational studies are well-suited for discovery but less so for causality.
• The utility of observational findings depends on the research question, design, analytical techniques, and data quality.
• Different designs (e.g., cohort, case-control) offer unique insights but have inherent limitations.

Conclusions:

• Observational studies are vital alternatives to RCTs when ethically or practically infeasible.
• Phase 4 studies are essential for evaluating real-world treatment effectiveness and identifying rare side effects.
• Improved reporting, including clear research questions, methods, and limitations, is needed for observational studies, with a call for STROBER guidelines.