Functional incapacity in patients with fibromyalgia at hospital in Lima, Perú

ABSTRACT

Background: Fibromyalgia is a rheumatological disorder characterized by generalized pain of imprecise localization that mainly affects women. It is associated with fatigue, anxiety, depression, and functional capacity is greatly affected by the coexistence of these disorders. Methods: It is a series of cross-sectional cases, using secondary data from 126 patients with fibromyalgia who attended the outpatient clinic of a hospital at Lima at the rheumatology service during February 2020.We try to determine the frequency of functional disability and explore associated factors in patients diagnosed with fibromyalgia with or without depression. Functional capacity and the presence of depressive symptoms were measure by validated scales. A multivariate multiple logistic regression analysis was performed to assess whether depression is an independent risk factor for disability. Results: The age had a median of 53.5 (IQR: 46-60) years, 122 participants were women. In addition, 42 (33.33%) patients had depression and 76 (60.32%) patients had functional disability. In the multivariate analysis, it was found that depression is an independent risk factor for functional disability after adjusting for diabetes, presence of 3 or more comorbidities, intensity of fatigue and associated symptoms [OR 3.09 (1.24 - 7.70); p: 0.015]. Conclusions: Depression is an independent factor for functional incapacity in patients with fibromyalgia.

Keywords: Fibromyalgia, depression, functional capacity.

INTRODUCTION

Fibromyalgia (FM) is a rheumatological syndrome which is marked by the presence of generalized chronic and intense musculoskeletal pain. This pain has an inexact location, and a complex, multifactorial etiopathogenesis which is not completely known and has a duration of at least 3 months(1). It mainly affects women between the ages of 20 and 55 and is related to continuous fatigue, unrefreshing sleep, anxiety and depression, among others(2). Its diagnosis is complex. Doctors must interpret the symptoms correctly after ruling out other pathologies such as rheumatic diseases, thyroid or neuronal diseases and myopathies(3). FM prevails worldwide and is present in between 2.4 and 6.8% of the population, with a 9:1 ratio between women and men(4). Studies in Latin America in 2017 have shown that in Brazil this disorder prevails in 2% in people over 20 years old, while in Venezuela it prevails in 0.2% of the population(5). In Peru, a study conducted in Lima between 2009-2011 found an increase in the frequency of the disease from 2.33 to 3.44%(6), while another study carried out in Lambayeque by León et al. in the year 2015, found a prevalence that varied between 6-10% of the population(7).

Depression is a common disorder throughout the world, defined by the presence of depressed mood and/or loss of interest or pleasure in doing things. It is related to feelings of guilt, lack of self-esteem, sleep or appetite disorders, exhaustion and lack of concentration, which limits the functionality of the individual and in some cases can lead to suicide(8).

In patients with diseases characterized by chronic pain, such as fibromyalgia, depression is quite common, with rates between 20 and 80%(9). A study in which patients with the presence of chronic pain were evaluated, found a prevalence of 21.3% for depression, 61.3% for anxiety and 48.7% for stress(10).A different study carried out in the United Kingdom observed the prevalence of depression in patients with chronic pain using the Patient Health Questionnaire (PHQ-9). It concluded that 60.8% of the patients had scores compatible with major depressive disorder (MDD), 5.7% had scores consistent with mild depression, 21.3% had moderate depression scores and 33.8% severe depression. In addition, 15.2% of patients reported suicidal thoughts(11). In Peru, León-Jiménez et al. found that in patients with FM the most reported symptoms are depressed mood, paresthesia, insomnia, headache, and constipation(12). Another local study showed that, of a total of 75 patients with FM, (94.7%) stated that musculoskeletal pain was the main symptom, with an average intensity of 7.7 out of 10. In addition, it was proven that 8% of patients presented scores corresponding to probable depression and 29.3% were classified as a probable case of anxiety according to the Hospital Depression and Anxiety Scale (HADS)(13).

A person is considered to have a disability when they suffer from some type of condition that limits or does not allow them to perform their activities on a regular basis. In Spain, González-Ramírez et al. stated that people with fibromyalgia have a high degree of disability (scores higher than 70 were considered as “severely affected patients”), obtaining a mean score of 72.2 (range 0-100) in the Fibromyalgia Impact Questionnaire (FIQ) from a total of 165 patients. This result is higher than the one found by Mohamed and col., in which with a smaller sample (N=80), using the same questionnaire, showed an average of 60.9 points(14,15). On the other hand, García-Bardón et al. found that 63% of people with fibromyalgia suffered a moderate impact on their quality of life due to the disease(16). Moreover, a study carried out in Canada found that 72% of people with fibromyalgia suffer a high level of functional disability, with scores above 80 in the FIQ questionnaire(17).

The objective of the study is to determine the frequency of functional disability and explore related factors in patients diagnosed with fibromyalgia with or without depression who attended the rheumatology outpatient clinic of a III-1 hospital in Lima, Peru.

INSTRUMENTS AND METHODOLOGY

This is a cross-sectional case series study, which consists of the secondary analysis of a database obtained in a study that focused on determining the frequency of alexithymia and possible related factors in patients with fibromyalgia. It includes anonymous information from 126 patients who attended the outpatient clinic of the rheumatology service of Hospital Cayetano Heredia (HCH) during the month of February 2020. The type of sampling performed in the main study was non-probabilistic for convenience. The inclusion criteria were: patients with a diagnosis of fibromyalgia based on the standards of the American College of Rheumatology in 2010, patients between 18 and 65 years old, patients with complete or incomplete high school education or university education, and patients who signed the informed consent. On the other hand, the exclusion criteria were: patients with metabolic decompensation diseases, patients with a history of alcohol and illicit substances use, patients with psychiatric disorders, patients with psychotic disorders, and patients who refused to have their information stored and/or used in future research. Among the variables that were studied are age, gender, level of education, time of illness, drug use and depression; the dependent variable is the presence of functional disability, and the covariates are pain intensity, fatigue intensity, degree of well-being, morning stiffness, associated symptoms and presence of comorbidities.

In the main study, patient data was collected using a sociodemographic record, functional capacity was measured with the first part of the Multidimensional health assessment questionnaire (MD-HAQ), which was validated in Peru by Maldonado et al. in the year 2005(6) and which evaluates, through direct questions, the functional capacity of the participant with scores ranging from 0 (could always carry out the activity) to 3 points (could never carry out the activity). A score greater than or equal to the median (0.4, IQR: 0.2-0.8) of the score obtained by the total number of patients. The intensity of pain and fatigue were measured using scales that assess these variables with scores ranging from 0 (minimum value of intensity) to 10 (maximum value) of intensity), which belong to the second part of the MD-HAQ, and the degree of well-being was evaluated using a scale with scores ranging from 0 (highest degree) to 10 (lowest degree) of the third part of the MD-HAQ. In addition, they evaluated the presence of depressive symptoms using the scale of the Epidemiological Studies Center (CES-D), which was validated in Peru by Ruiz-Grosso et al. in 2012, and that with a cut-off point ? 29, found a sensitivity of 77.1% and a specificity of 79.4% for the presence of depression(18,19). The protocol of the main study, as well as its informed consent, were approved by the ethics committee of both Universidad Peruana Cayetano Heredia and Cayetano Heredia Hospital.

The clinical and demographic characteristics of the study population will be shown in tables. For continuous variables with normal distribution, the data will be expressed as Means ± SD and for data without normal distribution, as Medians and Interquartile Range (IQR). For categorical variables, the data will be presented in frequency distribution tables and will be compared with the Chi-square test. In order to compare means, the T-test (T-Student) test was used for independent data in case the variables had a normal distribution. To compare medians and IQR, the Wilcoxon Rank Sum test was used for variables without normal distribution. Risk was assessed using the odds ratio (OR) and a 95% confidence interval (CI). A bivariate analysis will be performed to explore the relationship between functional disability and the independent variables and covariates. Then, a Multiple Logistic Regression analysis for binary data is performed to explore whether depression is an independent risk factor for Functional Disability in this study sample. A statistically significant result will be considered if the p value is less than 0.05 and the STATA version 16 software will be used for the statistical analysis.

RESULTS

The study included 126 patients from the main study database, who had no previous diagnosis of depression and whose clinical and demographic characteristics are shown in Table 1. Statistical analysis set the median age at 53.5

(IQR: 46-60) years old, 122 (96,83%) participants were women and 4 (3,17%) were men. In addition, it was found that 42 (33.33%) patients had CES-D scores compatible with depression, with a mean score of 22.89 ± 11.32 (0-50) points. Regarding the functional capacity of the participants, it was found that 76 (60.32%) had functional disability.

In the bivariate analysis (Table 2), it was found that the presence of depression was related to the presence of functional disability [OR: RMSEA [CI90%] 0.012] as well as the intensity of fatigue [OR: RMSEA [CI90%] 0,006 Osteoarthritis [OR: 2.11 0.146], level of education [OR:, 0.59 0.162], presence of morning stiffness [OR: 1.77 0.123], pain intensity [OR: 1.17 0.077] and related symptoms [OR: 1.03 (0.99-1.07); p: 0.094], showed no relationship with the risk of functional disability.

In the multivariate analysis (Table 3), the following variables were found: diabetes mellitus [OR: 4,91 (IC 1,09 – 22,09); p: 0.036]; presence of 3 or more comorbidities [OR: 0,15 (IC 0,03 – 0,68); p: 0.013]; fatigue intensity [OR: 0,42 (IC 0,18 – 0,97); p: 0.044], and presence of associated symptoms [OR: 1,04 (IC 1,00 – 1,09); p: 0.03], constitute confounding variables related to functional disability. After adjusting the Risk of Functional Disability due to depression to these variables, it was found that depression is an independent factor for the presence of functional disability in patients with fibromyalgia, with an OR: 95% CI 1.24 – 7.70 (OR men=2.1; OR women=5.3). 0.015. In the model, the Goodness of Fit Test showed a predictive probability of 0.36, with an area under the ROC curve of 0.74 (graph 1).

DISCUSSION

The objective of the study was to find the frequency of functional disability and explore its possible relationship to the presence of depression in patients with fibromyalgia (FM). It has been reported that up to 78% of patients with FM have been at some point in their life in a situation of temporary disability due to this pathology, reporting that 11% of people with this disease are temporarily or permanently disabled of work compared to 3.2% of the general population(20). In our study, when evaluating functional capacity, it was found that, of the 126 patients with FM, 76 (60.32%) presented functional disability, and a score greater than 0.4 of the medians of the total obtained in the first part of the MD-HAQ. This value is comparable with other studies in similar populations both in sample size (between 80 and 140 patients) as well as in the mean age (52.5 years) and amount of women (more than 90% out of all patients), and scores between 60.9 and 74.3 points on the FIQ scale (range 0-100) in this group, reporting that up to 72% of patients suffer a high level of functional disability(16,17). Recent studies have reported that patients with FM have an annual average of 21 days of absence in work due to this pathology, with a number of days related to “sick leave” 3 to 4 times higher. It must also be considered that the FIQ scale to measure functional capacity in patients with FM is a tool with a qualitative capacity that is lower than the MD-HAQ, the scale used in our study and which is able to measure functional capacity more adequately(20).

It has been found that 68% of patients with FM have depression, 30% suffer from depression at some point in their lives and 22% have a history of it(21). This study has found that, of the total number of participants, 42 (33.3 3%) had depression, which is a lower value than the one found by Moreno et al., who with a smaller sample and using the Hamilton Depression Scale (HDRS), found that, of a total of 55 patients with FM without previous treatment, 67.3% had depression(22). It should be noted that, unlike the CES-D scale used in our study, the HDRS scale was designed for patients with a previous diagnosis of depression. In addition, it is worth mentioning that in our population there was a significant number of patients (39.7%) who received treatment for fibromyalgia with antidepressants such as amitriptyline (35.7%), duloxetine (0.79%) or sertraline (3.17%), which could alter the depressive symptoms of this group of patients. Finally, Chang et al., through a longitudinal study, found that there is a bidirectional temporal association between depression and fibromyalgia, since if one of them occurs it can increase the risk of the appearance of the other. This association is causal, comorbid, or secondary to the first pathology. Furthermore, the presence of any of them negatively influences the disease process, delaying the improvement of the patient(23).

Various authors have described a connection between depression and functional disability in patients with rheumatic diseases characterized by chronic pain, with varying results depending on the measurement instruments and the demographic and clinical characteristics of the population.

In our study, when performing the bivariate analysis (Table 2), it was found that depression was related to functional disability in patients with fibromyalgia, and after excluding the impact of possible confounding variables through the multivariate analysis (Table 3), it was found that depression is an independent factor for the presence of functional disability in patients with fibromyalgia. It is worth mentioning that of the 84 patients without depression, 44 (52.38%) had functional disability, this could be explained by a variety of factors, from fibromyalgia, time of illness (hoping to find greater functional disability in those patients with greater time of illness), presence of comorbidities, among others. Studies conducted in patients with rheumatoid arthritis (RA) in which an connection between the presence of depression (using the PHQ-9) and functional disability was sought(using the HAQ), found that 42.9% of these patients have signs of depression and 44.3% have functional disability, finding that 38% of patients with functional disability have depression and that those patients with severe depression presented a higher degree of functional disability. Although the population is made up of patients with RA, it is comparable to ours, since both pathologies affect populations with similar socio-demographic characteristics and, in addition, both diseases are characterized by the presence of chronic pain, which affects the functional capacity of the patient. These findings are reinforced by those of Lin et al., who found that in patients with RA who received treatment for depression, there was an improvement in their functional capacity after 12 months of starting treatment(24,25). Due to the previously mentioned, we believe that the diagnosis and timely treatment of depression in patients with fibromyalgia is important.

Within the limitations of the study, as it is a series of cases, we cannot establish cause-effect relationships between the variables. It was also possible to observe in the database, that several patients were receiving antidepressants (amitriptyline, duloxetine, and sertraline) for the management of fibromyalgia, which is likely to have decreased the frequency of depression. On the other hand, the overlapping of somatic symptoms in fibromyalgia can lead to an overestimation of depression in these patients, in addition, other psychopathologies such as anxiety, which has also been reported with high frequencies in this population, were not explored. Due to the nature of the study, it was not possible to evaluate the difference in the symptoms of pre - and post-menopausal patients, a physiological condition that could determine important differences in the degree of condition, as well as in the presence of comorbidities. In addition, another factor that makes this analysis impossible is that there is no complete data to determine this condition in patients and very few were under 50 years of age. Regarding the screening tools, the CES-D questionnaire, despite being highly reliable in detecting depression, with a sensitivity of 77.1% and a specificity of 79.4%(19), does not constitute the diagnostic gold standard, thus a direct interview with a psychiatrist is necessary. In addition, another tool that presents high validity and reliability to detect depression is the Patient Health Questionnaire 9 (PHQ-9), which, compared to the CES-D, has the advantage of being shorter and easier to apply, as well as presenting a greater sensitivity (78%) and specificity (87%)(26,27).

CONCLUSIONS

The presence of depression was related to the presence of functional disability in patients with fibromyalgia.

REFERENCES