Elsevier

General Hospital Psychiatry

Volume 28, Issue 2, March–April 2006, Pages 154-160
General Hospital Psychiatry

Symptom Research
More than half of all outpatient visits are trigged by physical symptoms which, in turn, are not adequately explained by medical disorders at least half of the time. Further, the presence and severity of somatic symptoms often correlate more strongly with psychological, cognitive and behavioral factors than with physiological or biological findings. Finally, our understanding of the etiology, evaluation, and management of somatic symptoms and functional syndromes is less advanced than our knowledge of many defined medical and psychiatric disorders. This special section, edited by Kurt Kroenke, M.D., will highlight original studies that advance the science and clinical care of somatic symptoms.
The Spanish version of the FibroFatigue Scale: validation of a questionnaire for the observer's assessment of fibromyalgia and chronic fatigue syndrome

https://doi.org/10.1016/j.genhosppsych.2005.12.001Get rights and content

Abstract

Objective

To examine some of the psychometric properties of the Spanish version of the FibroFatigue Scale (FFS).

Methods

FFS was administered to 120 patients diagnosed with fibromyalgia and chronic fatigue syndrome. Internal consistency was evaluated by using Cronbach's α, test–retest reliability with weighted kappa and construct validity by correlations among FFS, the Fibromyalgia Impact Questionnaire (FIQ), the EuroQol 5D (EQ-5D) and the Hospital Anxiety and Depression Scale (HADS). The interrater reliability was tested using analysis of variance with patients and raters as independent factors.

Results

Internal consistency (α) was .88, test–retest reliability was .91, and interrater reliability was .93. Significant correlations were obtained between overall FFS and the FIQ (.55, P<.01), the EQ-5D (−.48, P<.01) and the HADS depression subscale (.25, P<.01), but not with the HADS anxiety subscale.

Conclusion

These results support the reliability and validity of the data obtained with the Spanish version of the FSS.

Introduction

Fibromyalgia (FM) and chronic fatigue syndrome (CFS) are both chronic clinical conditions characterized by a variety of nonspecific symptoms, including prominent fatigue, myalgia and sleep disturbances. Despite different diagnostic criteria, FM and CFS have many demographic and clinical similarities with few differences in the domains of symptoms [1], [2]. Up to 70% of the patients with CFS-like illnesses may have concurrent FM [3]. In fact, Wessely et al. [4] found a substantial overlap even within the entire group of functional somatic syndromes, including FM, CFS, irritable bowel syndrome and multiple chemical sensitivity, among others.

These two conditions have been assessed with self-rated scales; Fibromyalgia Impact Questionnaire (FIQ) [5] has been one of the most used questionnaires, to our knowledge, for the evaluation of the functional limitations and disability of FM, and several scales for the screening of CFS have been published [6], [7]. However, in psychiatry, observer's rating scales are also considered quite important in addition to self-rating scales [8]. For this reason, FibroFatigue Scale (FFS) was designed as a new observer's rating scale aimed at the assessment of core symptoms and treatment outcome in FM and CFS [9]. Due to substantial overlap in symptomatology between both conditions, the authors decided to develop a scale suitable for FM and CFS.

FFS is a 12-item observer's rating instrument, partially derived from the Comprehensive Psychopathological Rating Scale [10], [11], which measures pain, muscular tension, fatigue, concentration difficulties, failing memory, irritability, sadness, sleep disturbances, autonomic disturbances, irritable bowel symptoms, headache and subjective experience of infection [9]. FFS, in part, has been used as a primary endpoint in clinical trials evaluating the efficacy of different interventions in FM and CFS [12], [13], [14]. This scale has been already been translated into Italian and validated with acceptable psychometric properties [15].

The aim of the study is to validate a translated Spanish version of the FFS, that is, to examine the internal consistency, test–retest reliability, interrater reliability and construct validity of the data obtained with the Spanish version of the FFS.

Section snippets

Patients

The sample was made up of 120 patients (116 women and 4 men), aged 24–62 years (mean 46.7 years, S.D. 7.1 years) belonging to the Fibromyalgia and Chronic Fatigue Syndrome Association of Aragon. They were treated at the Somatoform Disorders Unit of the Miguel Servet University Hospital (Zaragoza, Spain). All of the patients from the Association who had attended the Unit during the year 2004 were invited to participate. To be included in the study, they had to fulfill either the American College

Results

One hundred twenty patients participated in the study. The median and the interquartile range (IQR) of the 12 items of the questionnaire are summarized in Table 1.

Discussion

The present data demonstrate the favorable psychometric characteristics of the data obtained with the Spanish version of the FFS that should define a valid and reliable test: internal reliability, test–retest reliability and interrater reliability. Construct validity has been demonstrated, as was expected, showing significant correlations between FFS and self-reported symptoms of FM (measured by FIQ) and significant inverse correlations between FFS and quality of life (assessed by EuroQol-5D).

Acknowledgments

This work has been possible thanks to the Red de Investigación en Actividades de Prevención y Promoción de la Salud/Research Network on Preventative Activities and Health Promotion (REDIAPP-G03/170), nodo de Aragón and Red Temática de Investigación Cooperativa “Psiquiatría de Enlace” (G03/128) from Instituto de Salud Carlos III, Madrid, Spain.

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