Original ArticlesBlinding was judged more difficult to achieve and maintain in nonpharmacologic than pharmacologic trials
Introduction
Blinding is a cornerstone of therapeutic assessment [1], [2], [3]. Indeed, studies not involving double-blinding yield exaggerated estimates of treatment effects [1], [4].
However, blinding patients and care providers is usually possible with a matching placebo in trials assessing drugs, but is often more difficult to carry out in trials assessing nonpharmacologic treatments (NPT) such as surgery, rehabilitation, and behavioral interventions [5]. Although some authors propose innovative solutions such as the use of standardized wound dressings [6] to blind patients and outcome assessors when assessing laparoscopic cholecystectomy, surgeons usually know what intervention has been applied, and patients usually know which rehabilitation program they followed.
Hip and knee osteoarthritis can be treated by a wide range of therapy with either pharmacologic treatments (PT) (i.e., involving the use of drugs) such as oral drugs, intra-articular injection, or topical treatments, or nonpharmacologic treatments (NPT) (i.e., involving treatments other than drugs) such as surgery, rehabilitation, joint lavage, acupuncture, behavioral interventions, or spa therapy.
The primary goal of this study was to compare the feasibility of blinding and the perceived risk of unblinding patients, care providers, and outcome assessors between reports assessing NPT, and those assessing PT of hip and knee osteoarthritis. The secondary aim was to compare the reporting of blinding patients, care providers, and outcome assessors between these reports.
Section snippets
Search strategy
We selected reports of all randomized controlled trials (RCTs) assessing NPT and PT in patients with hip or knee osteoarthritis published between January 1, 1992, and February 28, 2002, from the following journals (Journal citation reports 2001):
10 highest impact factors general and internal medicine journals: New England Journal of Medicine, Journal of the American Medical Association (JAMA), The Lancet, Annals of Internal Medicine, Annual Reviews Medicine, Archives of Internal Medicine,
Selected reports
Of the 198 reports identified, 119 were selected for assessment. The 79 reports excluded were abstracts only (n = 5), duplicate publications (n = 3), not randomized (n = 12), not assessing a therapeutic intervention (n = 45), not assessing treatment of hip and knee osteoarthritis (n = 13), or phase II trials (n = 1). Nine reports were secondarily excluded after we obtained the full text, as they were not randomized (n = 3) or were subgroup analyses (n = 1) or extended follow-ups of RCTs described in other
Discussion
This study assessed the feasibility of blinding, the perceived risk of unblinding and the reporting of blinding patients, care providers, and outcome assessors in reports of RCTs published over 10 years in 28 journals in the field of hip and knee osteoarthritis. Our results show that blinding patients, care providers, and outcome assessors was less often considered feasible in NPT than PT trials. Moreover, when blinding was considered feasible, the perceived risk of unblinding was more
Acknowledgements
The authors thank the two reviewers, Asbjorn Hrobjartsson and Victor M. Montori, for their help improving this report. This work was supported by a grant from the Caisse Nationale d'Assurance Maladie des professions indépendantes (CANAM) 93521 Saint-Denis, France, and the Assistance Publique des Hôpitaux de Paris (AP-HP).
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