Epidemiology of Fibromyalgia: East Versus West

Abstract

In this discussion, we explore the intricate and often misunderstood world of fibromyalgia. Epidemiological studies have a crucial role in enhancing our understanding of the prevalence and impact of fibromyalgia. These studies help us determine the necessary resources required to provide adequate assistance to affected individuals. Additionally, they help shape our medical practices by enabling us to diagnose, prognosticate, and select appropriate therapies based on population-based evidence [1].

In 1950, Graham introduced the concept of “pain syndrome” without a specific organic disease. Later in time, Smythe and Moldofsky coined the term “Fibromyalgia” after identifying areas of extreme tenderness called “pain points.” These points are defined as regions of hyperalgesia/allodynia with increased pressure. In 1990, the American College of Rheumatology (ACR) established diagnostic criteria for fibromyalgia, which have been recently modified.

The ACR criteria from 1990 can be used to diagnose fibromyalgia with a sensitivity of 88.4% and a specificity of 81.1%. These criteria are based on two variables: (1) experiencing pain on both sides of the body, both above and below the waist, which is characterized by centralized pain, and (2) experiencing chronic generalized pain that lasts for at least 3 months, which is characterized by pain on palpation in at least 11 of 18 specific body sites [2].

The prevalence of fibromyalgia may differ depending on the diagnostic criteria used. The 1990 criteria are stricter than the 2010 criteria, resulting in only more severely affected patients being identified as having fibromyalgia.

In 2010, the diagnostic criteria for fibromyalgia were revised. The new criteria removed the requirement of a tender point and the absence of a disorder that would otherwise explain the pain. This new diagnostic criterion is considered to be particularly helpful in evaluating patients over time, with a sensitivity of 93.1% and specificity of 91.7%. The focus is on the patient's self-reported physical symptoms and cognitive impairment. The diagnostic criteria were revised again in 2016, with the use of a Widespread Pain Index (WPI) of 7, a Symptom Severity (SS) scale score of 5, or a WPI of 3–6 and an SS scale score of 9 to identify fibromyalgia. These revisions have improved the sensitivity of the diagnostic criteria.

Between the ages of 30 and 50 years, women are more likely to experience symptoms of this condition compared to men. In fact, women have a seven to nine times higher incidence rate than men. However, this condition can affect individuals of all ages, including children, adolescents, and the elderly [1].

Fibromyalgia (FM) affects around 2%–8% of the global population. However, diagnosing FM is challenging as different countries use varying standards to diagnose it. Additionally, almost 84% of FM patients have comorbid disorders, with 67% having other musculoskeletal conditions, 35% having psychological disorders, 27% having gastrointestinal disorders, 23.5% having cardiovascular disorders, and 19% having endocrinological disorders.

There are many coexisting conditions, such as depressive disorder, anxiety disorder, bipolar disorder, rheumatoid arthritis, osteoarthritis, gout, vasculitis, coronary heart disease, hypertension, diabetes, irritable bowel syndrome, Crohn's disease, cancer, peripheral neuropathy, and others, that can significantly affect the treatment and outcome of a disease. This impact can be anywhere between two and seven times more severe [1].

Despite its global prevalence, fibromyalgia is often difficult to diagnose, with an average delay of 2.3 years. Patients with comorbid conditions may experience more severe symptoms than those with isolated fibromyalgia.

In addition to comorbid conditions with FM, there is also a “fibromyalgia syndrome” that encompasses “overlapping symptoms” of multiple conditions. It can be difficult to differentiate pain symptoms caused by rheumatic conditions from centralized fibromyalgia pain, particularly with the recognition of central sensitivity syndrome in fibromyalgia among patients with rheumatoid arthritis, axial spondylarthritis, psoriatic arthritis, and other conditions. This recognition has led to a higher incidence of fibromyalgia than previously reported in the general population.

Fibromyalgia is a condition that shares symptoms with other diseases including lupus, multiple sclerosis, rheumatoid arthritis, polymyalgia rheumatica, axial spondylarthritis, thyroid disease, T2DM, anemia, chronic fatigue syndrome, statin-induced myalgias, hypothyroidism, various inflammatory or rheumatic conditions, neuropathic conditions, sleep apnea syndrome, somatoform disorders like anxiety or depression, and viral illnesses [3].

In Iran's 2008 COPCORD study, Bangladesh rural areas had the highest percentage of FM cases with 4.4%, while Iran ranked fifth with 1.3% in rural areas and 0.7% in urban areas [4].

In 2021, the urban areas of Tehran, Zahedan, and Sanandaj were 0.79% and 0.06% in Tuyserkan's rural areas [5].

The prevalence of the condition varied among women based on diagnostic criteria and was lower in rural areas compared to urban areas [6].

The prevalence of fibromyalgia (FM) varies across different countries. In Venezuela, the lowest overall prevalence was recorded at 0.2%. In Ecuador urban, the prevalence was higher at 9.5%. The prevalence of FM in Argentina was found to be 0.1%; whereas in Japan, it was 2.1%, with females accounting for almost half of the cases.

Japan had the lowest rate of pain reported, which was 4.4%, and treated, which was 26.3%, compared to other developed countries. In the United States, 23.8% of people experienced pain, and 40.1% of them were treated. In Europe, including the United Kingdom, France, Germany, Italy, and Spain, 20.2% of people experienced pain, and 47% of them were treated [6]. In China, the prevalence of FM was 0.07% [7].

Asia, Africa, Americas, and Europe have been studied as part of the global epidemiology of fibromyalgia. However, there has only been one study conducted in Africa, specifically in Tunisia, while no studies have been conducted in Oceania [8].

The following statistics provide information about the prevalence of fibromyalgia (FM) across different regions of the world. The global prevalence of FM is 2.7%, with a range from 0.4% in Greece to 9.3% in Tunisia. In the United States, the prevalence is 3.1%, while in Europe, it is 2.5%, and in Asia, it is 1.7%. The mean prevalence of FM in women is 4.2%, whereas in men, it is 1.4%, resulting in a female-to-male ratio of 3:1.

In Saudi Arabia, the prevalence of FM is notably higher at 13.4%. A study showed that 15% of hospitalized patients had FMS, of which 91% were women. In France, the prevalence of FM is much lower at 1.60% among 3081 people over the age of 18 [9].

Fibromyalgia, a chronic disorder characterized by widespread pain and fatigue, is prevalent in regions affected by war and conflict. In Damascus, Syria, 11.8% of the population reportedly suffers from FM, while in Lebanon, the figure stands at 7%. This can be attributed to several factors such as death, displacement, emigration, unemployment, poverty, social and educational challenges, low wages due to economic inflation, and lack of access to health insurance. The ongoing COVID-19 pandemic has also contributed to the rise in FM cases in these areas [10].

According to the most recent report from the National Fibromyalgia Association, around 10 million people in the United States and 3%–6% of the world's population are believed to be affected by fibromyalgia. The condition is more common in women, with 75%–90% of cases occurring in females. Fibromyalgia often runs in families, affecting siblings and even mothers and their children. The condition usually affects people between 20 and 50 years of age, and around 8% of those aged 80 years or above meet the ACR criteria for fibromyalgia. Lastly, it is worth checking the health insurance database to find out more about this condition [8]:

The author declares no conflicts of interest.