Objective: To describe evidence grading methods employed in the systematic reviews in this special series of articles. To provide an overview of results of these reviews to critique the quality of rehabilitation research. To identify issues in the application of evidence grading methods to rehabilitation.
Design: Conceptual review of evidence-based practice and evidence grading methods. English-language research studies on rehabilitation of persons with spinal cord injury, traumatic brain injury, and burn for the 5-yr period of 1999-2004 were reviewed using methods of the American Academy of Neurology supplemented by Cochrane criteria and summarized.
Results: Rehabilitation has a shortage of high-level studies. The number of level 1 treatment studies was quite limited (five in spinal cord injury, 15 in traumatic brain injury, 12 in burn rehabilitation), as was the number of level 2 studies (26, 4, and 2, respectively). Despite the large number of correlational studies published, the number of high-level (1 or 2) diagnostic and prognostic studies was surprisingly limited (34, 11, and 5, respectively). The rate of production of high-level studies is rapidly increasing. Problems were encountered in applying standard evidence criteria to complex issues encountered in some studies, suggesting limitations and issues in evidence grading methodology.
Conclusions: Rehabilitation needs more high-level studies. Some improvements in research methodology are relatively affordable (e.g., improved blinding), whereas others are expensive (e.g., large randomized controlled trials). Lower-level investigations reporting promising results need to be followed by more definitive, higher-level trials.