Although the word "arthritis" means joint inflammation, the term is used to describe around 200 rheumatic diseases and conditions that affect joints, the tissues that surround the joint, and other connective tissue.5
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You will also see introductions at the end of some sections to any recent developments that have been covered by MNT's news stories. Also look out for links to information about related conditions.
Fast facts on arthritis
Here are some key points about arthritis. More detail and supporting information is in the main article.
- "Arthritis" defines around 200 rheumatic disease and conditions that affect joints.
- Rheumatic diseases include various types of arthritis, as well as osteoporosis and systemic connective tissue diseases.
- Types of arthritis such as lupus and rheumatoid arthritis affect multiple organs and cause a long list of symptoms.
- According to the US Centers for Disease Control and Prevention (CDC), 52.5 million adults report having been diagnosed by their doctor with some form of arthritis.
- Arthritis can impair a person's ability to perform "everyday" tasks.
- Physical activity has a positive effect on arthritis and can improve pain, function and mental health.
- The most common comorbid condition experienced with arthritis is heart disease.
- Factors in the development of arthritis include injury, abnormal metabolism, genetic makeup, infections and immune system dysfunction.
- Treatment for arthritis aims to control pain, minimize joint damage and improve or maintain quality of life.
- Arthritis is treated with a combination of medications, physical therapies and patient education and support.
What is arthritis?
The term "arthritis" is used to describe numerous rheumatic diseases and conditions that affect joints.
Rheumatic conditions are typically characterized by pain, aching, stiffness and swelling in and around one or more joints. The symptoms can develop gradually or suddenly. Certain rheumatic conditions can also involve the immune system and various internal organs of the body.6
Some forms of arthritis, such as rheumatoid arthritis and lupus, can affect multiple organs and cause widespread symptoms.
Arthritis is more common among adults aged 65 years or older, but people of all ages (including children) can be affected.
Prevalence of arthritis
There are 52.5 million adults in the US, equating to 22.7% of the population, reported to have a form of arthritis, rheumatoid arthritis, gout, lupus or fibromyalgia.1
With people living longer in the US, the prevalence of doctor-diagnosed arthritis is expected to increase. It has been estimated that by the year 2030, 67 million, 25% of the projected total adult population aged 18 years and older, will have doctor-diagnosed arthritis.
Arthritis has a significantly higher age-adjusted prevalence in women (23.9%) than men (18.6%), with the prevalence increasing with age and higher among women than men in every age group. According to the CDC, 60% of people with arthritis are women, and most forms of arthritis are more common in women, with the exception of gout, which is more common in men.
An estimated 294,000 children under the age of 18 have some form of arthritis or rheumatic condition; this represents approximately 1 in every 250 children in the US.4
Impact of arthritis
Arthritis has a significant impact on individuals, for example:1
- Almost 43.2% (22.7 million) of adults with arthritis report limitations in their usual activities
- 40% report that it is "very difficult" or they "cannot do" at least 1 of 9 important daily functional activities
- Almost 8 million adults who report an activity limitation due to arthritis also report severe limitation in their ability to stoop, bend, or kneel, and 6 million cannot walk 0.25 miles
- 31% (8.3 million) of working age adults with arthritis report limitations in work.
Impairment in the ability of people with arthritis to perform essential daily tasks may interfere with their work, their sense of purpose in their community, or the care they can provide for their family.
Around 18% of total disabilities are caused by arthritis or rheumatism, making it the most common cause of disability in the US.
Arthritis has a strong association with major depression, with an attributable risk of 18.1% according to the CDC. This is thought to be most likely caused by the limitations arthritis can place on function and enjoyment of life. Around 6.6% of adults with arthritis report severe psychological distress.51
According to the CDC, the prevalence of arthritis increases with body mass index (BMI): almost 16% of adults who are under/normal weight have arthritis; almost 23% of overweight adults have arthritis; and almost 31% of obese adults have arthritis.5
Arthritis can place limitations on everyday activities. Having a higher BMI is associated with an increase in activity limitations related to arthritis, with such limits reported by:2
- 38.2% of people who are under/normal weight
- 37.2% of people who are overweight
- 44.8% of people who are obese.
Arthritis and exercise
Physical activity and exercise have been shown to benefit people with arthritis by improving pain, function and mental health. However, around 24% of adults with arthritis report being physically inactive compared with 18.6% of adults without arthritis.2
By partaking in low levels of exercise, individuals with arthritis face placing themselves at risk of conditions associated with lack of activity such as cardiovascular disease, diabetes, obesity and functional limitations.
Risk factors for arthritis
Certain factors have been shown to be associated with a greater risk of arthritis. Some of these risk factors are modifiable while others are not.
Non-modifiable arthritis risk factors:
- Age: the risk of developing most types of arthritis increases with age
- Sex: most types of arthritis are more common in females; 60% of all people with arthritis are female. Gout is more common in males than females
- Genetic: specific genes are associated with a higher risk of certain types of arthritis, such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and ankylosing spondylitis.
Modifiable arthritis risk factors:
- Overweight and obesity: excess weight can contribute to both the onset and progression of knee osteoarthritis
- Joint injuries: damage to a joint can contribute to the development of osteoarthritis in that joint
- Infection: many microbial agents can infect joints and trigger the development of various forms of arthritis
- Occupation: certain occupations that involve repetitive knee bending and squatting are associated with osteoarthritis of the knee.
The cost of arthritis
Cost attributable to arthritis and other rheumatic conditions (AORC) in the US in 2003 was approximately:2
- $128 billion in total costs - 1.2% of the 2003 US gross domestic product (GDP)
- $80.8 billion direct costs - the largest components were for ambulatory care (52.1%), inpatient care (20.0%) and prescription drugs (19.3%)
- $47.0 billion indirect costs - lost earnings
- By state, a total ranging from $226 million in the District of Columbia to $12.1 billion in California.
The CDC reports that 47% of US adults with arthritis also have at least one comorbid condition (the presence of more than one disease or condition in the same person at the same time).3
Among people with arthritis the most common comorbidities are:
- Heart disease - 24% (11.2 million)
- Chronic respiratory conditions - 19% (9.0 million)
- Diabetes - 16% (7.3 million)
- Stroke - 6.8% (3.2 million).
Risk factors for other chronic conditions are common among US adults with arthritis, such as:
- High blood pressure - 53%
- Physical inactivity - 47%
- High cholesterol - 47%
- Obesity - 36%
- Smoking - 19%.
More than half (53%) of US adult with arthritis report high blood pressure. High blood pressure is associated with heart disease - the most common comorbidity among adults with arthritis.
Approximately 1 in 5 (19%) of US adults with arthritis are smokers. Smoking is associated with chronic respiratory conditions - the second most common comorbidity among adults with arthritis.
Smoking also adversely affects the synthesis of collagen, the key protein making up connective tissue and the scaffolding of bone, as well as increasing oxidative damage and decreasing circulation and the supply of nutrients to the joint tissues and bone. As such, smoking is detrimental to the health of joints and bone and contributes to arthritis development and progression.
Hospitalizations from arthritis
In 2004, there were an estimated:4
- 744,000 hospitalizations with a principal diagnosis of arthritis
- 5 million hospitalizations with a principal or secondary diagnosis of arthritis
- 78 million ambulatory care visits with a primary diagnosis of AORC.
Data from the Healthcare Cost and Utility Project (HCUP) 2011 Nationwide Inpatient Sample (NIS) estimates that in 2011:52
- 6.7 million hospitalizations (17.3% of all hospitalizations) were associated with a diagnosis of arthritis or rheumatic condition (AORC)
- Most of the 6.7 million hospitalizations were associated with osteoarthritis (OA), gout, rheumatoid arthritis and other less specific disorders
- OA accounts for 47.4% of all arthritis-related hospitalizations; 3,161,100 hospitalizations for OA as principal diagnosis.
In 2011, knee and hip joint replacement procedures (usually for OA) accounted for 35% of total arthritis-related procedures during hospitalization.53
In 2004, joint replacements for arthritis included:4
- 454,652 total knee replacements
- 232,857 total hip replacements
- 41,934 shoulder replacements
- 12,055 other joint replacements.
Between 1992 and 2011, there was an increase of 217% in the rate of total knee replacements (from 203.6 to 645.1 per 100,000 people). There was also a 119% increase in the rate of total hip replacement (from 139.9 to 306.6 per 100,000).52
Between 1979 and 1998, deaths related to arthritis or rheumatic conditions (AORC) increased from 5,537 to 9,367.4 The approximate death rate from AORC in 1979 was 2.46 per 100,000 population, rising to 3.48 per 100,000 population in 1998. Both rates age-standardized to the year 2000 population were 2.75 and 3.51, respectively.
Using 10 categories of AORC, just three categories accounted for almost 80% of deaths:9
- Diffuse connective tissues diseases: 34% - mostly systemic lupus erythematosus (SLE) and systemic sclerosis
- Other specified rheumatic conditions: 23% - mostly vasculitis
- RA: 22%.
What causes arthritis?
There is no single cause of all types of arthritis; the cause or causes in any given case vary according to the type or form of arthritis. Potential causes for arthritis may include:
Potential causes for arthritis may include:
- Injury - leading to degenerative arthritis
- Abnormal metabolism - leading to gout and pseudogout
- Inheritance - such as in osteoarthritis
- Infections - such as in the arthritis of Lyme disease
- Immune system dysfunction - such as in RA and SLE.
Most types of arthritis are caused by a combination of many factors working together, although some arthritis conditions have no obvious cause and appear to be unpredictable in their emergence.
Some people may be more susceptible to certain arthritic conditions due to their genetic makeup. Additional factors, such as previous injury, infection, smoking and physically demanding occupations, can interact with a person's genes to further increase the risk of arthritis.
Osteoarthritis is caused by a reduction in the normal amount of cartilage tissue through wear and tear throughout life.
Diet and nutrition can play a role in managing arthritis and the risk of arthritis, although specific foods, food sensitivities or intolerances are not known to cause arthritis. Foods that increase inflammation, particularly animal-derived foods and diets high in refined sugar, can exacerbate arthritis. Similarly, eating foods that provoke an immune system response can exacerbate arthritis symptoms.
Gout is one type of arthritis that is closely linked to diet as it is caused by elevated levels of uric acid which can be a result of a diet high in purines. As such, diets that contain high-purine foods, such as seafood, red wine and meats can trigger a gout flare-up. Vegetables and other plant foods that contain high levels of purines do not appear to exacerbate gout symptoms, however.
Cartilage is a flexible, connective tissue in joints that absorb the pressure and shock created from movement like running and walking. It also protects the joints and allows for smooth movement.34
Rheumatoid arthritis occurs when the body's immune system attacks the tissues of the body, specifically connective tissue, leading to joint inflammation and pain and degeneration of the joint tissue.
Recent developments on arthritis causes from MNT news
The joints that "crack" are often the knuckles, knees, ankles, back and neck, and there are numerous reasons why these joints "sound off." However, can your knuckle-cracking habit that aggravates the masses give you arthritis? Or is it just another harmless habit?
Children prescribed courses of antibiotics were found to have twice the risk of developing juvenile arthritis than children who did not receive antibiotics, according to the findings of a new study published in Pediatrics.
On the next two pages we look at the types of arthritis, the signs and symptoms and the possible treatment options for arthritis.