Journal of clinical epidemiology
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Randomized Controlled Trial
An advance letter did not increase the response rates in a telephone survey: a randomized trial.
To test the impact of an advance letter on response and cooperation rates in a nationwide telephone survey, given previous inconsistent results. ⋯ An advance letter was not seen to be effective in increasing response or cooperation rates in a nationwide telephone survey. Researchers should consider alternative methods of increasing participation in telephone surveys.
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The aim of this study was to determine the smallest worthwhile effects of two treatments for nonspecific low back pain (LBP). ⋯ People with chronic back pain need to see larger effects on pain of NSAIDS than physiotherapy to consider the effects of these interventions worthwhile. These estimates of the smallest worthwhile effect can be used to interpret the findings of clinical trials and to design adequately powered clinical trials.