Relationship Between Weight and Severity of Fibromyalgia

Abstract

Fibromyalgia is a chronic pain syndrome with diffuse pain, muscle weakness, and other symptoms. A relationship between the severity of symptoms and obesity has been observed.

Objective

To determine the relationship between weight and the severity of fibromyalgia.

Material and Methods

42 patients with fibromyalgia were studied. BMI and fibromyalgia severity are classified weight by FIQR. Results: The mean age was 47.3 ± 9.4 years, 78% presented severe and extreme fibromyalgia, and 88% were overweight or obese. There was a positive correlation between the severity of the symptoms and the BMI (r = 0. 309). The reliability test for FIQR presented a Cronbach’s α of 0.94.

Conclusion

About 80% of the participants do not show controlled symptoms, and their prevalence of obesity is high, observing a positive correlation between both.

Introduction

Fibromyalgia was recognized in 1990 by the American College of Rheumatology (ACR)¹ and in 1992 by the World Health Organization (WHO).² In 1990, the ACR created the Diagnostic Criteria for Fibromyalgia,^3,4 which was last updated in 2016.⁵ It is conceptualized as a chronic pain syndrome with diffuse pain, accompanied by muscle weakness and various symptoms such as chronic fatigue, sleep disorders, morning stiffness, headache, cognitive disturbances, anxiety, depression, irritable bowel syndrome, and others.^1,4,6–8

The worldwide prevalence of fibromyalgia is 2 to 4%,⁹ and in Mexico, 0.7%.¹⁰ It affects women with a 9:1 ratio compared to men, and the ages of most significant impact are between 25 and 50 years of age.^3,7 Numerous factors increase the propensity to suffer it, such as infections, trauma, autoimmune diseases, and psychological stress.^6,11

Within the pathophysiology of fibromyalgia, there is evidence of central and peripheral sensitization, with alterations at the cerebral level, in sleep hours, presence of small fiber neuropathy, muscle and skin alterations, decreased serum levels of serotonin and melatonin and increased pro-inflammatory cytokines, increased oxidants and decreased antioxidants and polymorphisms in genes related to serotonin, dopamine, and substance P.^{1, 3, 7–9, 11–19}

The WHO recognized obesity in 1997 as a pathological entity of its own.²⁰ Suarez defines it as an abnormal or excessive accumulation of fat that can be detrimental to health. Pasca and Montero also gave a complete definition: “Chronic systemic, multi-organ, metabolic and inflammatory disease, multidetermined by the interrelationship between the genomic and the environmental, phenotypically expressed by an excess of body fat (about the sufficiency of the organism to accommodate it), which carries an increased risk of morbidity and mortality.”²¹

The WHO refers to a prevalence of overweight and obesity in adults of 52% globally,²⁰ the Panamerican Health Organization (PAHO) of 58% in Latin America and the Caribbean, and the National Institute of Public Health (INSP) 72.5% in Mexico.^22,23 The WHO considers that the fundamental cause of obesity is an energy imbalance between calories consumed and calories expended due to an increase in the intake of high-calorie foods rich in fat and a decrease in physical activity.²⁰

Obesity can be peripheral and central; in the former, hyperplasia of the adipocytes remains functional, with an accumulation of peripheral subcutaneous fat. In the second, there is hypertrophy of the adipocytes, with translocation of fatty acids to the liver, heart, muscle, pancreas, and brain and release of pro-inflammatory factors, such as IL-6 and TNF-α, and insulin resistance.²¹

Other authors have found a significant relationship between increased pain and obesity (p=0.016) and symptom severity and obesity (p=0.017). Likewise, a low positive correlation was found between pain and seriousness to obesity (r=0.277, p=0.002; r=0.292, p=0.001).²⁴

Due to those mentioned above, this study was conducted to determine the relationship between weight and fibromyalgia severity, using the Revised Fibromyalgia Impact Questionnaire (FIQR), since there are no studies on this subject Mexican population, nor studies on obesity in fibromyalgia using the FIQR.

Material and Methods

A descriptive, correlational and retrospective study was conducted, of 42 participants with a diagnosis of fibromyalgia, contacted in the rheumatology and pain clinic of physicians in Durango, Mexico, as well as in the associations “Por el Derecho a Existir con Fibromialgia y EM/SFC” and “CreSer Fibromialgia Bajío”; during the years 2019 and 2020. The inclusion criteria were aged 30 to 70 years and who met the 2016 Fibromyalgia Diagnostic Criteria from the ACR. The exclusion criteria were pregnant or postpartum women, as well as cancer.

Sociodemographic data were collected through a structured questionnaire. To classify the severity of fibromyalgia, the FIQR was used, which is an author-reported Likert-type scale containing 21 items divided into three components (function, widespread impact, and severity of symptoms)²⁵ and which considers a maximum of 100 points, classifying it as mild (0–42 points), moderate (43–59 points), severe (60–74 points) and extreme (75–100 points). Its Spanish version was validated by Salgueiro et al. with a Cronbach’s α coefficient of 0.95.²⁶

For the anthropometric measurement, the body mass index (BMI) was taken into account, which classifies weight as underweight (<18.5), normal (18.5–24.9), overweight (25–29.9), and obese (≥30).²⁰

The information was analyzed with the IBM SPSS Statistics 21 statistical program, looking for measures of central tendency, graphs, normality tests, chi-square, Pearson correlation, and reliability tests.

The research had the approval of the Academic Committee of the Master’s Degree in Health Sciences of FAMEN-UJED and the Research Committee and Research Ethics Committee of Hospital General 450 (folio #166). It complied with the Regulations of the General Health Law on Health Research and the International Ethical Guidelines for Biomedical Research on Human Subjects, and all participants signed an informed consent form.

Results

The were 49 participants who agreed to participate in this study: 42 fulfilling the inclusion criteria. The mean age was 47.3 ±9.4 (30–64) years. Table 1 shows their sociodemographic characteristics.

Table 1.

Sociodemographic characteristics of the participants.

Source: Author's elaboration

Variable		n	%
Sex	Women	37	88
	Men	5	12
Marital status	Single	10	24
	Married	24	57
	Free Union	3	7
	Divorced	5	12
Education	Middle school	5	12
	High school	9	21
	Bachelor's degree	18	43
	Master's degree / PhD	10	24
Occupation Employee	Employee	17	41
	Businessman	4	9
	Trader	2	5
	Housekeeper	5	12
	Retired	4	9
	Disability pensioner	1	3
	Unemployed	4	9
	Other	5	12

Thirty-one percent of the participants mentioned having one or more family members with fibromyalgia, and only six participants reported not suffering from any other pathology besides fibromyalgia. They presented a fibromyalgia evolution time of 16.7 ±13.2 (3–52) years, with a delay of 9.6 years between the onset of symptoms and their diagnosis. Regarding fibromyalgia severity, a mean of 70.3 ±16.9 (27–98) points on the FIQR was obtained. Seventy-eight percent were found to have severe to extreme fibromyalgia (Figure 1).

Figure 1.

Classification of the severity of fibromyalgia

Source: Author's elaboration

Within the anthropometric measurements, a mean weight of 77.2 ±13.5 (49.0–107.2) kg, height of 1.63 ±0.07 (1.45–1.80) m and BMI of 29.0 ±4.6 (18.0–41. 9) kg/m2, observing that 88 % of the participants were located between overweight and obesity, with 48 % of those overweight being concentrated in severe fibromyalgia and 88% of those obese being equally distributed between severe and extreme fibromyalgia (Figure 2).

Figure 2.

Classification of body mass index by the severity of fibromyalgia

Source: Author's elaboration

Shapiro-Wilk goodness-of-fit tests were performed for the severity and BMI variables, finding a normal distribution of the data (p=0.081 and p=0.100, respectively). Chi-square tests were performed, which were not significant (p=0.817). However, it was observed that 89.4 % of those with severe fibromyalgia and 85.7 % of those with extreme fibromyalgia were overweight or obese (Table 2).

Table 2.

Chi-square for the severity of fibromyalgia and BMI.

		BMI				Total
		Underweight	Normal	Overweight	Obesity
Severity	Mild	0	0	3	1	4
	Moderate	0	1	3	1	5
	Severe	1	1	10	7	19
	Extreme	0	2	5	7	14
Total		1	4	21	16	42

Source: Author's elaboration (p=0.817)

BMI: body mass index

The three components of the FIQR were analyzed (Table 3), finding significant data in the third component (symptoms), with a positive correlation between this and BMI (r=0.309). The correlations with the first (function) and second (overall impact) components and the FIQR as a whole were not statistically significant. A reliability test was performed for the FIQR, finding a Cronbach’s α of 0.94.

Table 3.

Pearson's correlation between BMI and FIQR score, including its three components.

Variable	Correlation	P
Fibromyalgia severity	0.127	0.424
Function (FIQR1)	−0.007	0.963
Overall Impact (FIQR2)	−0.080	0.614
Symptoms (FIQR3)	0.309*	0.046

Source: Author's elaboration

^*statistically significant.

BMI: body mass index

FIQR: Revised Fibromyalgia Impact Questionnaire

Discussion

Fibromyalgia is chronic and has very diverse symptomatology. It has a worldwide prevalence of 2 to 4% and 0.7% in Mexico; however, due to the little knowledge about it and the difficulty of its diagnosis, these data could underestimate the true prevalence. The mean age found, 46.6 ±9.93 years, agrees with the ages of the most significant impact of 25 to 50 years that have been recorded,³ falling within the range of the economically active population. Although 67% have professional or higher education, only 55% are gainfully employed, which could be because the severity of the symptoms does not allow them to maintain a job.

Of the six participants who reported having no comorbidities, only two were not overweight or obese, so the prevalence of comorbidities was higher than in Spanish patients (84 %).²⁷ A delay of 9.6 years was found between the onset of symptoms and diagnosis, confirming the difficulty in diagnosis. Even though 93% take medication to control their symptoms, only four participants present mild fibromyalgia, finding 78% between severe and extreme, with a mean of 70.3 ±16.9 points on the FIQR, similar to what was found when the instrument was validated in its Spanish version.²⁶

The mean BMI was 29.0 ±4.6 kg/m², very similar to that of other Mexican and Turkish patients.^{28, 29} A large number of overweight participants present severe fibromyalgia (48%) and most of those with obesity present severe to extreme fibromyalgia (88%); these anthropometric alterations could be caused by the sedentary lifestyle of most of the patients, mostly generated by the multiple uncontrolled symptoms of the disease, which in turn causes an increase in these symptoms, and consequently a cycle that deteriorates the quality of life.^24,30,31

When studying the three components of the FIQR separately, it was found that the third (severity of symptoms) presents a positive correlation with BMI (r=0.309). Despite the sample size, the above resembles other investigations using scales different from the FIQR, with samples of more than 100 patients. A reliability test of the FIQR was performed to assess whether the instrument was adequate, finding a Cronbach’s α of 0.94, similar to that presented by Salgueiro when validating his Spanish version²⁶, which is essential since it is a more updated instrument to assess the severity of fibromyalgia specifically.

One limitation of this study is the small number of participants, due to the underdiagnosis of the disease and the health crisis caused by the SARS-CoV-2 pandemic, which led to the suspension of many specialty medical consultations and preventive health measures, including social isolation. Another limitation was the lack of information on the level of exercise of the participants. Nevertheless, we consider that the data obtained during this investigation reflect the magnitude of the effects of weight concerning the severity of fibromyalgia. It would be important to conduct a longitudinal study to observe whether the weight decrease would lead to the decrease in fibromyalgia severity.

Conclusion

Most of the participants present at least one pathology in addition to fibromyalgia. We observed that about 80% of the participants do not show controlled symptomatology, and their prevalence of obesity is high; this, added to the fact that it was observed that there is a positive correlation between the severity of symptoms and BMI. This leads us to conclude that it would be of great importance to conduct a study with a larger sample, where the leading causes of obesity in these patients are also investigated, to find better treatments to reduce the symptomatology and improve the quality of life. We found that the Spanish version of the FIQR is a reliable instrument for the population studied, so it can continue to be used in the Mexican people for subsequent studies.