Placebo and nocebo response magnitude on temporomandibular disorders related-pain: a systematic review and meta-analysis.

OBJECTIVES:

The aim of this systematic review (SR) was to answer the following question: "In adult patients with temporomandibular disorders (TMD) related-pain, what is the placebo or nocebo effect of different therapies?"

METHODS:

A SR was performed with randomized clinical placebo-controlled trials on diagnosed painful TMD studies from five main databases and from three grey literature. Studies included must to have sample older than 18 years, with painful TMD, which diagnosis was done by Research Diagnostic Criteria (RDC/TMD) or Diagnostic Criteria (DC/TMD).

RESULTS:

Out of 770 articles obtained, 42 met the inclusion criteria for qualitative and 26 for quantitative analysis. Meta-analysis indicated mean variation on pain intensity for placebo therapy was higher on laser acupuncture with 45.5mm points reduction, followed by avocado soybean extract with 36mm, and amitriptyline 25mg with 25.2mm. Laser showed a 29% of placebo effect, as well medicine with 19% and other therapies with 26%. Possible nocebo effect of 8% pain increase was found for intra-articular injection of ultracain.

CONCLUSIONS:

Based on the available data, the placebo response could play a major effect on TMD pain management and may be responsible from 10 to 75% of pain relief. Laser acupuncture, avocado soybean and amitriptyline promoted the higher placebo effect. Possible nocebo effect was found only for Ultracain Injection with 8%.

CLINICAL RELEVANCE:

Clinicians could apply such evidence to optimize pain management and judgment about treatment efficacy and researches may find it useful when designing their investigations. This article is protected by copyright. All rights reserved.