What is the age of onset for rheumatoid arthritis?

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The overall likelihood of an individual developing RA increases with age, but it is most common in females aged 25–45 years.

If RA develops in adults aged 65 or younger, doctors refer to it as early onset RA. When RA develops in individuals over the age of 65, doctors refer to it as elderly onset RA (EORA) or late onset RA (LORA).

The RA age of onset matters because it can influence an individual’s outlook and treatment.

There are three main risk factors that increase the likelihood of RA being fatal: disease severity, disease activity, and the presence of other health conditions.

The age of onset for RA plays a significant role in determining the severity of the disease and the treatment options. It also affects disease progression and the chance of individuals developing other conditions alongside RA, known as comorbidities.

Additionally, the age of onset affects the sexes differently. RA tends to occur more frequently in females, but EORA may affect males and females at a similar rate.

According to the Arthritis Foundation, adults with early stage RA may not have discoloration or swelling of the joints, but they may have tenderness or pain in the affected areas.

Other symptoms of RA include:

• pain, swelling, stiffness, or tenderness in multiple joints lasting 6 weeks or more
• symptoms first affecting smaller joints, such as the wrist and the joints in the hands and feet
• symptoms occurring equally on both sides of the body
• morning stiffness lasting for at least 30 minutes

Many people with RA also become exhausted or fatigued and may have a low grade fever.

The symptoms that a person experiences and their intensity may not be consistent. For example, RA symptoms commonly come and go, alternating between flares of significant inflammation and pain and periods of remission.

Risk factors that increase the likelihood of developing RA include:

• Age: Although RA can begin at any age, the possibility increases with age.
• Sex: Females are two to three times more likely to develop RA than males.
• Genetics: Some people inherit specific genes called human leukocyte antigen (HLA) class II genotypes that confer an increased risk of developing RA and experiencing more severe symptoms. Environmental factors, which include obesity and smoking, further increase these individuals’ risk of RA.
• Smoking: Smoking cigarettes increases the risk of developing RA and worsens disease severity.
• Early life exposures: Certain early life exposures may increase the risk of RA in adulthood. For example, children who had exposure to cigarette smoke when in the womb are twice as likely to develop RA.
• Obesity: Having excess body weight increases the risk of RA, with the risk correlating with the severity of obesity.

People who have breastfed infants may have a reduced risk of developing RA.

EORA occurs in individuals over the age of 65 years. Although early onset RA is more prominent in females, EORA has a more similar distribution between males and females.

Doctors often diagnose EORA earlier in the disease, and although it is frequently acute with symptoms coming on quickly, it is less erosive or damaging to the bones than early onset RA. Additionally, EORA often involves larger joints such as the shoulders rather than the small joints of the hands.

Among those with EORA, fewer individuals may test positive for rheumatoid factor (RF), an immune system protein that may attack healthy tissues. Overall, 80% and 60–70% of individuals with RA test positive for RF and cyclic citrullinated protein (CCP), respectively, according to the American College of Rheumatology.

The treatment for RA and EORA may differ. Treating young adults with RA typically involves disease-modifying antirheumatic drugs (DMARDs) and biologics. In comparison, doctors commonly treat those with EORA with lower dosages or less potent DMARDs, biologic medications, or both. Generally, they avoid corticosteroids for these individuals due to the long-term side effects.

The various ways that EORA presents can make it challenging for doctors to diagnose, and it requires different clinical and treatment approaches.

Juvenile idiopathic arthritis (JIA) is the type of arthritis that doctors most commonly diagnose in children and teenagers.

The term idiopathic means unknown, and it signifies a lack of knowledge about why some children develop JIA. Doctors speculate that children with JIA have specific genes that bacteria, viruses, or other external factors activate, but research is ongoing to confirm this theory.

There are seven types of JIA, which doctors distinguish by:

• signs
• symptoms
• number of affected joints
• laboratory results
• family history

The seven types of JIA are:

• Oligoarticular JIA: This type affects four joints or fewer in the initial 6 months of the disease. Children, especially young girls, who test positive for anti-nuclear antibodies are at risk of the inflammatory eye disease uveitis.
• Enthesitis-related JIA: This condition commonly affects the hips, knees, and feet, causing tenderness where the bone meets a tendon, ligament, or other connective tissue.
• Rheumatoid factor-negative polyarticular JIA: Individuals with this type of JIA test negative for RF. It affects five or more joints in the initial 6 months of disease.
• Rheumatoid factor-positive polyarticular JIA: This type also affects five or more joints, but affected individuals test positive for RF and CCP.
• Systemic JIA: People with systemic JIA may experience joint pain, rash, high fever, and systemic illness lasting 2 weeks or more.
• Psoriatic JIA: This condition also involves psoriasis, an autoimmune disease that affects the skin.
• Undifferentiated arthritis: Some people’s condition may not fit into one of the above categories. In such cases, doctors will describe it as undifferentiated arthritis.

Anyone experiencing symptoms of RA should seek medical attention. It is important to receive an accurate diagnosis quickly, as appropriate, timely treatment can limit the effects of RA and their impact on someone’s life.

Rheumatologists are doctors who specialize in RA, and they are the most suitable healthcare professionals to diagnose the condition accurately. They will take the individual’s medical history, perform a physical exam, and request laboratory tests and imaging studies to make a diagnosis.

RA can develop in people of any age, from children to older adults. The disease appears most commonly in females aged 25–45 years, but it can also affect people at an older age.

Some defining differences between RA and EORA include:

• distribution between sexes
• disease progression
• disease severity
• treatment

JIA affects children and teenagers, and the seven subtypes differ by their characteristics.

It is crucial for anyone experiencing symptoms of RA to speak with a doctor. A proper diagnosis and early treatment are essential to prevent the disease from significantly affecting an individual’s life.