Effectiveness of a cognitive behavioral intervention in patients with medically unexplained symptoms: cluster randomized trial
Authors: López-García-Franco Alberto , del-Cura-González Mª Isabel , Caballero-Martinez Luis , Sanz-Cuesta Teresa , Díaz-García Marta Isabel , Rodriguez-Monje Mª Teresa , Chahua Marcela , Muñoz-Sanchez Inmaculada , Serrano-González Dolores , Rollán-Llanderas Teresa , Nieto-Blanco Esther , Losada-Cucco Liliana , Caballero-Martínez Fernando , Sanz-García Nuria , Pose-García Belén , Jurado-Sueiro Montserrat , Rey Manuela Luque , de Blas González Francisca García , Abanto Mª Angeles Miguel , Bayona Teresa Sanz , Ayllón-Camargo Rafaela , Lopez Inmaculada Santamaría , Hernando María Luisa Santiago , Beltran-Alvarez Rosario , Aguilar-Gutierrez Ana Isabel , Mota-Rodriguez Jose Luis , Cosculluela-Pueyo Rafaél , López-Martín-Aragón Teresa , Bonilla-Sanchez Rosa , Aritieda-González-Granda Mª Carmen , Razola-Rincón Raquel , Sanchez-de-la-Ventana Mª Angeles , Martinez-Guinea Concepción , Huerta-Galindo Luis , Barrio-Ovalle Ana Belén , Miguel-Martín Susana , Portero-Fraile Paz , Pensado-Freire Higinio , Herrera-Garcia Mª Luisa , Azcoaga-Lorenzo Amaya , Gómez-García Inés , Llamas-Sandino Nuria , López-Borja Isabel , Maldonado-Castro Hortensia , Lumbreras-Villarán Patricia , Ascanio-Durán Carlos 
Published: May 2012

Abstract

Background
Medically unexplained symptoms are an important mental health problem in primary care and generate a high cost in health services.
Cognitive behavioral therapy and psychodynamic therapy have proven effective in these patients. However, there are few studies on the effectiveness of psychosocial interventions by primary health care. The project aims to determine whether a cognitive-behavioral group intervention in patients with medically unexplained symptoms, is more effective than routine clinical practice to improve the quality of life measured by the SF-12 questionary at 12 month.

Methods/design
This study involves a community based cluster randomized trial in primary healthcare centres in Madrid (Spain). The number of patients required is 242 (121 in each arm), all between 18 and 65 of age with medically unexplained symptoms that had seeked medical attention in primary care at least 10 times during the previous year. The main outcome variable is the quality of life measured by the SF-12 questionnaire on Mental Healthcare. Secondary outcome variables include number of consultations, number of drug (prescriptions) and number of days of sick leave together with other prognosis and descriptive variables. Main effectiveness will be analyzed by comparing the percentage of patients that improve at least 4 points on the SF-12 questionnaire between intervention and control groups at 12 months. All statistical tests will be performed with intention to treat. Logistic regression with random effects will be used to adjust for prognostic factors. Confounding factors or factors that might alter the effect recorded will be taken into account in this analysis.

Discussion
This study aims to provide more insight to address medically unexplained symptoms, highly prevalent in primary care, from a quantitative methodology. It involves intervention group conducted by previously trained nursing staff to diminish the progression to the chronicity of the symptoms, improve quality of life, and reduce frequency of medical consultations.

Trial registration
The trial was registered with ClinicalTrials.gov, number NCT01484223 [http://ClinicalTrials.gov].