Non-randomized studies:  An evaluation of search strategies, taxonomy and comparative effectiveness with randomized trials in the field of low-back pain.
Published: 2006
Language: eng
Number of pages: 175
ISBN-13: 9780494218921
Description: Randomized controlled trials (RCT) are considered the most reliable method of determining the effects of treatments. However, RCTs may sometimes be impossible, unethical, imprecise, invalid or irrelevant and the practitioner must rely on evidence from non-randomized studies (NRS).To test the influence of methodological quality and clinical homogeneity in the agreement between NRSs and RCTs, we compared 48 pairs of matched interventions. We identified a trend showing that pairs of lower-quality studies disagreed more than pairs in which at least one study was of higher quality. However, the most significant finding was that highly homogeneous pairs showed higher agreement than less homogeneous pairs.A search of MEDLINE and EMBASE yielded 225 articles. In the absence of specific search strategies for NRSs, we developed and tested one based on a dynamic method. It showed a sensitivity of 90% to 100% compared with 95% to 100% using a fixed set of search terms, proving that it is possible to limit search strategies to NRSs.We compared the results of NRSs and RCTs of three surgical interventions for low-back pain. NRSs either agreed with or underestimated the effects of RCTs. Other clinical factors (presence of spondylolisthesis, previous surgery and involvement of workers' compensation) were frequently more powerful explanatory variables than randomization.The objectives of this thesis were to (1) search for NRSs that compared two or more interventions for low-back pain, (2) identify a taxonomy to classify study designs, and (3) compare the results from NRSs and RCTs of the same interventions, exploring the influence of different variables.We found a widely-used taxonomy of study design that classified studies as "experimental", "observational" and "descriptive" and tested its inter-rater reliability on 30 randomly selected studies from our database. There was good agreement in 56% of the studies and poor agreement in 44%. Therefore, even with instructions and definitions the assignment of labels was not reliable.Despite the difficulties in searching for NRSs and the challenges of classifying their study designs, we recommend that review authors include evidence from both RCTs and NRSs when assessing the effects of health-care interventions.
Notes: Source: Dissertation Abstracts International, Volume: 68-01, Section: B, page: 0200.

Thesis (Ph.D.)--University of Toronto, 2006.

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