Arthritis, or rheumatoid arthritis (RA), is a chronic autoimmune disease that mainly affects the joints, but can also affect various organs. It is characterised by inflammation of the synovial membrane, painful flare-ups, and a risk of ankylosis and joint deformities. Its prevalence in France is estimated between 0.49% and 0.77% of the adult population, and it affects approximately three women for every man. In Canada, the prevalence among adults is about 1.4%, reaching 3.3% among women aged 65 and over. In the United States, approximately 1.3 million people are diagnosed. Although its exact cause remains unknown, a genetic predisposition and environmental factors are involved.
Arthritis, acute or chronic inflammation of one or more joints, encompasses more than a hundred diseases classified among the many varieties of arthritis or that cause it. The most widespread and troublesome forms manifest simultaneously in several joints (polyarthritis); they can become chronic and progress to impotence.
Rheumatoid arthritis is a rheumatic disease, the most serious form of chronic polyarthritis and the most painful, as well as potentially the most disabling, since it can block movement (ankylosis) and deform the joints. Chronic in nature, it is characterised by flare-ups interspersed with remissions. It is located mainly in the joints, but is also a systemic condition that can affect various organs and alter general health (fever, fatigue, weight loss).
Joint inflammation can also correspond to gout. Acute rheumatic fever, now rare in developed countries, is an autoimmune polyarthritis that occurs following streptococcal tonsillitis and can lead to cardiac complications. Ankylosing spondylitis affects the spine.
The cause of this disease is unknown, but it appears that a hereditary predisposition and an environmental factor (a virus, for example) may contribute to its onset. Furthermore, it is known to be an autoimmune disease. It exists throughout the world, in all climates and all ethnic groups. It affects approximately 3% of the population in developed countries, with women being three times more affected than men.
The diagnosis of RA is based on a combination of clinical, immunobiological, and radiological evidence. Biological testing reveals an inflammatory syndrome in nearly 90% of cases. Rheumatoid factor is present in approximately 60% of cases, and anti-cyclic citrullinated peptide (anti-CCP) antibodies, which are highly specific, in 60 to 70% of cases.
There are many methods for treating rheumatoid arthritis. Drug treatment relieves symptoms, particularly pain (analgesics, anti-inflammatories). Disease-modifying antirheumatic drugs, such as methotrexate, and biologics (anti-TNF) aim to control inflammation and slow the progression of the disease. Physiotherapy and occupational therapy are also of great help: exercise programmes, physical therapy (heat applications, for example), and the use of devices designed to maintain motor function and joint mobility. Disability occurring in advanced cases can be significantly corrected by surgery.
Prevalence and impact in France, Switzerland, Canada, and the United States
Rheumatoid arthritis is a disease whose prevalence varies considerably by region and by estimation method.
In France, a recent study based on the National Health Data System (SNDS) estimates that the prevalence of RA in adults was between 0.49% and 0.77% in 2019, with the true prevalence likely falling within this range. The disease predominantly affects women, with a sex ratio of 3 to 1. The most frequent causes of death in patients with RA are linked to cardiovascular diseases in 27% of cases.
In Canada, data from Quebec indicate that in 2022-2023, 1.4% of people aged 20 and over had been diagnosed with RA. This proportion increases with age, reaching 3.3% among women aged 65 and over and 2.1% among men of the same age. Rheumatoid arthritis is the most common form of inflammatory rheumatic disease in Canada. An Ontario study showed that the proportion of people with rheumatic diseases continuing a pregnancy increased by 24% between 2011 and 2020, with RA increasing by 22%.
In Switzerland, data specific to the prevalence of RA are less detailed. National registries, such as that of the Swiss Society of Rheumatology, provide information on management but not precise prevalence rates in the sources consulted.
In the United States, approximately 1.3 million Americans are currently diagnosed with rheumatoid arthritis. Prevalence is estimated between 0.5% and 0.8% of the population. An analysis based on Global Burden of Disease (GBD) 2021 data reveals significant geographical disparities: Montana has the highest prevalence (464.73 per 100,000), while the District of Columbia and California have the lowest rates. RA-related mortality decreased significantly between 1999 and 2019, but rebounded in 2020, coinciding with the COVID-19 pandemic.
Overall, rheumatoid arthritis represents a significant health and economic burden in Western countries, with notable geographical and demographic disparities. Population ageing and the increase in comorbidities contribute to the rising prevalence observed in many regions.
Sources
France: PREST Study (SNDS) / Assurance Maladie (Ameli) / Espace Infirmier / La Revue du Praticien
Switzerland: Office fédéral de la santé publique (OFSP) / Sociétés suisses de rhumatologie
Canada: Ministère de la Santé et des Services sociaux du Québec (INSPQ) / NIH (National Institutes of Health)
United States: ACR Meeting Abstracts (GBD 2021) / NIH (PubMed) / Pennsylvania General Assembly
