BMJ  2005;330:672 (19 March), doi:10.1136/bmj.330.7492.672-b

Letter

Managing osteoarthritis of the knee

Conclusions about use of NSAIDs are misleading

The first 150 words of the full text of this article appear below.

EDITOR—The meta-analysis by Bjordal et al of randomised controlled trials assessing the efficacy of non-steroidal anti-inflammatory drugs (NSAIDs) in osteoarthritic knee pain is technically well done, but the authors' conclusions are misleading.¹ They assert that the mean change in pain, as measured on a visual analogue scale, over placebo was 10.1 mm (95% confidence interval 7.4 to 12.8) and claim a non-relevant difference, since the minimal clinically perceptible difference was 9.7 mm.²

They mixed up the interpretations at group and individual levels. Indeed, 9.7 is the perceptible difference at the individual level (a change lower than 9.7 mm would not be perceived by the patient). However, the 10.1 mm estimate assessed by Bjordal et al makes sense only at the group level.

To understand this multilevel interpretation better, we performed some calculations, classifying patients as improved or not if they achieved a change greater than 10.1 mm. Thus, . . . [Full text of this article]

florence.tubach@bch.ap-hop-paris.fr, INSERM U738; Groupe Hospitalier Bichat-Claude Bernard (Assistance Publique—Hôpitaux de Paris); Faculté Xavier Bichat (Université Paris 7), 46 rue Henri Huchard, 75018 Paris, France

INSERM U738; Groupe Hospitalier Bichat-Claude Bernard (Assistance Publique—Hôpitaux de Paris); Faculté Xavier Bichat (Université Paris 7), 46 rue Henri Huchard, 75018 Paris, France

INSERM CIC 202, Faculté de Médecine, 2 bis Bd Tonnellé, 37032 Tours, France

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