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Research: LINDE and colleagues,
Listed in Issue 75
Abstract
LINDE and colleagues, Institute for Social Medicine Epidemiology, Charite Hospital, Humboldt-Universitaet, 10098, Berlin, Germany, Klaus.Linde@lrz.tu-muenchen.de, investigated differences between randomized and non- randomized clinical trials in terms of patient characteristics, intervention characteristics, quality aspects, response rates and the provision of additional useful information (e.g. long-term effects, side effects, prognostic indicators), in order to determine whether non-randomized studies should be included in systematic reviews. They used the case of acupuncture for the treatment of chronic headache.
Background
Methodology
The researchers performed meta-analysis of clinical trials of acupuncture for chronic headache. Studies had to include at least 5 patients and report clinical outcome data. Studies were identified through searches of Medline, Embase, the Cochrane Controlled Trials Register, other databases and bibliographies.
Results
They identified 24 randomized trials and 35 non-randomized studies (5 non-randomized, controlled cohort studies; 10 prospective, uncontrolled studies; 10 case series; and 10 cross-sectional surveys). Randomized trials had smaller sample sizes, met more quality criteria and produced lower response rates (0.59) versus 0.78. Studies that met more quality criteria produced lower response rates. There was no difference in follow-up periods between randomized and non-randomized studies. 3 non- randomized studies included an analysis of prognostic variables. Only 1 non-randomized study reported on side effects. Non-randomized studies confirmed the finding of a systematic review of randomized trials that acupuncture is likely to be effective in the treatment of chronic headache. However, non-randomized studies provided little relevant additional information on long-term effects, prognostic factors or side effects.
Conclusion
References
Linde K et al. Should systematic reviews include non-randomized and uncontrolled studies? The case of acupuncture for chronic headache. Journal of Clinical Epidemiology 55 (1): 77-85. Jan 2002.