Fibromyalgia and eating disorders in morbid obesity

Sir,

Prevalence rates of obesity and morbid obesity (MO) in Spanish adults are 22.9% and 0.6%, respectively.¹ On the other hand, overweight and obesity are very common in people with fibromyalgia, with a prevalence ranging from 32% to 50%.² Some recent data suggest that excess weight worsens the symptoms of fibromyalgia, and has even been shown to be negatively related to quality of life and positively related to pain.^3,4 It has also been noted that high body mass index (BMI) correlates to greater pain and fatigue levels in people with fibromyalgia, which may represent an aggravating comorbid condition by negatively affecting quality of life, with a resultant physical dysfunction.⁴ A number of mechanisms have been proposed to explain this relationship between obesity and fibromyalgia, including reduced physical activity, sleep disturbances, or depression problems, as well as dysfunction of the thyroid gland or the somatotropic axis.⁵

Therapeutic options for subjects with MO include bariatric surgery (BS), whose medical and psychological benefits have been previously shown in multiple studies.⁶ Because of the increasing number of people with MO who are candidates for BS with fibromyalgia, our aim was to assess whether the presence of fibromyalgia was associated with differences in sociodemographic profile, eating behavior characteristics, and the degree of anxiety in these patients.

From January 2012 to December 2013, 40 women who were candidates for bariatric surgery, of whom 10 (25%) were diagnosed with fibromyalgia, were consecutively recruited. Obese males with fibromyalgia were not identified, and no male was therefore recruited into the study. Sociodemographic variables (age, marital status, number of children, degree of disability, use of drugs, mental health history, and treatment with psychoactive drugs) and variables related to MO (time of start of obesity, family history of MO, result of psychological evaluation, and surgery performed) were collected. The following questionnaires were administered to assess eating behavior and degree of anxiety: the Eating Disorder Inventory (EDI-2) and the State-Trait Anxiety Questionnaire (STAI-II). EDI-2 is an adequate psychometric instrument both for assessing the psychological characteristics of anorexia and bulimia and for screening to identify people at a high risk of eating disorders. Moreover, its use is approved in many protocols for assessing patient candidates for BS.⁷

The group of women with MO and no fibromyalgia (n = 30) had a BMI of 44.8 ± 7.0 (mean and standard deviation), while women with both MO and fibromyalgia (n = 10) had a BMI of 43.4 ± 4.2 (p = 0.559). Analysis of the results showed no statistically significant differences in any of the sociodemographic or obesity-related variables collected, nor in the degree of anxiety and the pattern of eating disorders.

The results suggest that although fibromyalgia is a chronic disease that causes great physical, social, and cognitive dysfunction in nonobese people, it does not imply per se changes in the sociodemographic or psychological profile of patients with MO who are candidates for BS, nor a greater risk of the occurrence of eating disorders in these patients. Physical disability and the low self-esteem frequently associated with obesity may possibly neutralize some aspects of health directly related to fibromyalgia such as pain and fatigue. In other words, obesity in general, and particularly morbid obesity, may be an aggravating factor of fibromyalgia.

One of the limitations of this study is that only baseline data were collected before bariatric surgery. In this case, an additional aspect to be considered is what happens to these patients after the weight loss achieved with BS. Although a clear improvement in the symptoms associated with fibromyalgia has been reported with weight loss achieved through BS,^7,8 the following question arises: will the persistence of fibromyalgia lead to a poorer mid or long-term prognosis in such important aspects as excess weight loss, increased quality of life achieved with weight loss, or long-term maintenance of weight loss? By answering it, we may learn whether or not the therapeutic approach to fibromyalgia in women undergoing surgery should differ from the standard approach to this disease.