The aim of this study was to evaluate the clinical significance of a sham intervention on pain intensity in patients with CLBP undergoing either active or sham interferential current therapy (IFC), and to examine the effects of a limited and enhanced therapeutic alliance.
A retrospective data analysis of an experimental, placebo-controlled, repeated-measures study was conducted. A total of 117 individuals with chronic low back pain (CLBP) were randomly assigned to 4 groups: (1) Active limited (AL) (n=30), which received a single session of active IFC combined with limited TA; (2) Sham Limited (SL) (n=29), which received a single session of sham IFC combined with limited TA; (3) Active Enhanced (AE) (n=29), which received a single session of active IFC combined with enhanced TA; and (4) Sham Enhanced (SE) (n=29), which received a single session of sham IFC combined with enhanced TA. Pain intensity was assessed using a numerical rating scale (PI-NRS). Clinical significance was assessed using distribution and anchor-based methods with calculation of the smallest detectable difference (SDD) and the minimal important difference (MID) for each of the outcomes of interest.
Mean differences (before-after) on the PI-NRS were 18.17, 30.28, 22.00, and 10.14 for the AL, AE, SE, and SL groups, respectively. All groups showed a clinically significant treatment effect based on their effect sizes (ES) of 1.8 (AL), 3.3 (AE), 1.6 (SE), 0.9 (SL) and small detectable differences (SDD) of 6.63 (AL), 7.33 (AE), 5.71 (SE) and 5.95 points (SL) respectively. In addition, MIDs calculated based on anchor-based methods confirmed clinically significant treatment effects in three (AL, AE and SE) of the four groups. In addition, MIDs calculated based on anchor-based methods, considering the patient’s perspective, indicated that interventions using an enhanced TA produced clinically relevant effects, as perceived by the patients, when compared to those without enhanced TA.
Placebo/sham response in patients with CLPB can achieve clinically significant effects as perceived by patients. Contextual factors such as the therapeutic alliance seem to have a notable influence, suggesting that sham-enhanced treatment (SE) may be as effective as both active interventions targeted in this study (AL, AE).
In clinical practice, these observations highlight the necessity of contemplating the placebo response and the TA when devising and executing treatment strategies for patients with chronic conditions such as CLBP. It is possible for physiotherapists to utilize the beneficial aspects of a placebo/sham response. Furthermore, the TA should be used to improve treatment outcomes. It is crucial to acknowledge that the patient's perception of the therapist and the therapeutic process can exert a considerable influence on the efficacy of both active and sham treatments, which can be either beneficial or detrimental.
placebo response
low back pain
