Challenges in Systematic Reviews That Evaluate Drug Efficacy or Effectiveness

21 June 2005 | Volume 142 Issue 12 Part 2 | Pages 1066-1072

Increasingly, consumers, clinicians, regulatory bodies, and insurers are using systematic reviews of drug interventions to select treatments and set policies. Although a systematic review cannot provide all the information a clinician needs to make an informed choice for therapy, it can help decision makers distinguish what claims about effectiveness are based on evidence, identify critical information gaps, desc ribe features of the evidence that limit applicability in practice, and address whether drug effectiveness differs for particular subgroups of patients. To improve the relevance and validity of reviews of drug therapies, reviewers need to delineate clinically important subgroups, specific aims of therapy, and most important outcomes. They may need to find unpublished trials, studies other than direct comparator (head-to-head) trials, and additional details of published trials from pharmaceutical manufacturers and regulatory agencies. In this paper, we address ways to formulate questions relevant to specific clinical therapeutic aims; discuss types of studies to include in drug efficacy and effectiveness reviews and how to find them; and describe ways to assess applicability of studies to actual practice.

Author and Article Information

From McMaster University Evidence-based Practice Centre, Hamilton, Ontario, Canada; and Portland Veterans Affairs Medical Center and Oregon Health & Science University Evidence-based Practice Center, Portland, Oregon.

Grant Support: This research was performed under contract to the Agency for Healthcare Research and Quality (contract 290-97-0017), Rockville, Maryland. Dr. Raina holds a Canadian Institutes of Health Research (CIHR) Investigator Award and a Premier's Excellence Award (PREA) from the Ontario Provincial Government.

Potential Financial Conflicts of Interest: Authors of this paper have received funding for Evidence-based Practice Center reports.

Requests for Single Reprints: Parminder Raina, PhD, Department of Clinical Epidemiology & Biostatistics, McMaster University, DTC Room 306, 1280 Main Street West, Hamilton, Ontario L8S 4L8, Canada.

Current Author Addresses: Dr. Santaguida: Department of Clinical Epidemiology & Biostatistics, McMaster University, DTC Room 309, 1280 Main Street West, Hamilton, Ontario L8S 4L8, Canada.

Dr. Helfand: Oregon Health & Science University, Mail Code BICC, 3181 SW Sam Jackson Park Road, Portland, OR 97239.

Dr. Raina: Department of Clinical Epidemiology & Biostatistics, McMaster University, DTC Room 306, 1280 Main Street West, Hamilton, Ontario L8S 4L8, Canada.