Efficacy of Acceptance and Commitment Therapy (ACT) in Group in Fibromyalgia

Efficacy of Acceptance and Commitment Therapy (ACT) in Group in Fibromyalgia: a Randomized, Controlled Study.

The main objective is to assess the efficacy of Acceptance & Commitment Therapy (ACT) in group for the treatment of fibromyalgia. The secondary aims are: 1.- To assess the cost-effectiveness of ACT and 2.- To assess the efficacy of ACT in other variables such as anxiety, depression, pain or global function. 3.- To evaluate the usefulness or electroencephalographic cordance as a prognostic variable of the treatment.

HYPOTHESIS: ACT in group is effective for improvement of pain acceptance and other outcome variables (pain, anxiety, depression, global function) in fibromyalgia, and it is cost-effective. Cordance is an useful predictor of treatment efficacy in these patients.

DESIGN: Multicentre, randomized, controlled study, with parallel groups, and a 6-month follow-up period. Participants will be randomly allocated to one of two conditions: 1.- Group Acceptation & Commitment Therapy or 2.- Treatment as usual by his general practitioner. Patients diagnosed of fibromyalgia, according to the American College of Rheumatology, will be recruited in primary care. Assuming an alpha=0.05 and p=80%, using two tails, and calculating 5% of refusals, it will be necessary a sample size of 55 patients for each group of patients.

The main outcome will be pain acceptance. Other outcome measures will be global function (assessed with the Fibromyalgia Impact Questionnaire, FIQ), cost-effectiveness (evaluated by the Client Service Receipt Inventory, CSRI) and electroencephalographic cordance. The mediating variables included are anxiety and depression (assessed with the Hospital Anxiety and Depression scale, HADS) and pain (measured with an analog visual scale). A psychiatric interview will be administered to the participants to diagnose Posttraumatic Stress Disorder. Statistical analysis will be carried out for intention to treat, and using the method Last Observation Carried Forward. A Repeated Measures Mixed Model will be used to study the main outcome. All calculations will be made with two tails and a significance of 0.05.

Inclusion Criteria:

1. Age: 18-65 year old
2. Discontinuation drug treatment 7 days before the start of the trial
3. Not having received psychological treatment previously or at least in the last 2 years
4. Ability to understand Spanish
5. Given consent to participate in the study

Exclusion Criteria:

1. Age: <18 year old and > 65 year old
2. Clinical or psychological disease that, at investigator's opinion, can interfere the psychological examination or the adherence to psychotherapy (dementia, alcohol or drug abuse, psychosis, severe personality disorder)