Effect moderators in Internet-based exposure therapy for fibromyalgia: The role of pain intensity.

BACKGROUND: A recent randomized controlled trial (N = 140) was indicative of large and sustained average improvements of Internet-based exposure for fibromyalgia, as compared to a waitlist. However, little is known about who benefits the most from this treatment. OBJECTIVES: To test for potential moderating effects of age, educational attainment, the duration of fibromyalgia, baseline overall fibromyalgia severity, pain intensity, fibromyalgia-related avoidance behaviour and symptom preoccupation on the waitlist-controlled effect of 10 weeks of Internet-based exposure for fibromyalgia. METHODS: Secondary analysis of a randomized controlled trial (ClinicalTrials.gov NCT02638636). We used linear mixed effects models to determine whether the waitlist-controlled effect of exposure therapy on overall fibromyalgia severity (Fibromyalgia Impact Questionnaire) differed as a function of the potential moderators. RESULTS: Only pain intensity (0-10) was found to be a significant moderator, where a higher baseline pain intensity predicted a more limited waitlist-controlled effect of Internet-based exposure (B = 3.48, 95% CI: 0.84-6.13). Standardized point estimates of effects were small for the sociodemographic variables, and in the moderate range for some clinical variables that did not reach statistical significance such as behavioural avoidance and time with the fibromyalgia diagnosis. CONCLUSIONS: Results suggest that Internet-based exposure treatment was more useful for participants with lower baseline levels of pain, and less so for participants with higher baseline levels of pain. The treatment had relatively similar effects across the other tested moderators. SIGNIFICANCE: This study evaluated potential effect moderators in exposure-based treatment for fibromyalgia. Results indicated that a higher level of pain intensity at baseline was predictive of a less favourable outcome. It may be extra important to monitor progression for these patients and to provide additional therapeutic support when needed.

Internet-Delivered Exposure Therapy for Fibromyalgia: A Randomized Controlled Trial.

BACKGROUND: Fibromyalgia (FM) is a common and disabling chronic pain disorder, for which existing pharmacological and psychological treatments have yet yielded insufficient effects. Previous literature has shown that exposure therapy may be an effective treatment for chronic pain. This study constitutes the first randomized controlled trial evaluating exposure therapy for FM. METHODS: A total of 140 participants with diagnosed FM were randomized to a 10-week Internet-delivered exposure treatment (iExp; n=70) or a waitlist control condition (WLC; n=70). Primary outcome measure were FM symptoms and impact, and secondary outcome measures were fatigue, disability, quality of life, pain-related distress and avoidance behaviors, insomnia, depression, and anxiety. RESULTS: Data retention was high (100% data completion at posttreatment for primary outcome, 96% at 6-month follow-up and 94% at 12-month follow-up). Results showed that participants in the iExp group made large and superior improvements compared with WLC on FM symptoms and impact (B, -1.93; z, -10.14; P<0.001, between-group Cohen d=0.90), as well as all secondary outcomes (between-group Cohen d ranging from 0.44 to 1.38) with sustained results. CONCLUSIONS: We conclude that iExp seems to be an efficacious treatment for FM compared with no treatment, and the results also highlight the potential increase of accessibility by using the Internet format to deliver psychological treatments for these patients. Future trials with active control conditions are warranted.