Objective
To provide a single source for the best available estimates of the US prevalence of and number of individuals affected by osteoarthritis, polymyalgia rheumatica and giant cell arteritis, gout, fibromyalgia, and carpal tunnel syndrome, as well as the symptoms of neck and back pain. A companion article (part I) addresses additional conditions.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/art.23177

Estimates of the prevalence of arthritis and other rheumatic conditions in the United States. Part II.

BACKGROUND Although the rising pandemic of obesity has received major attention in many countries, the effects of this attention on trends and the disease burden of obesity remain uncertain. METHOD ...

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Health Effects of Overweight and Obesity in 195 Countries over 25 Years.

OBJECTIVE
To provide a single source for the best available estimates of the US prevalence of and number of individuals affected by osteoarthritis, polymyalgia rheumatica and giant cell arteritis, gout, fibromyalgia, and carpal tunnel syndrome, as well as the symptoms of neck and back pain. A companion article (part I) addresses additional conditions.


METHODS
The National Arthritis Data Workgroup reviewed published analyses from available national surveys, such as the National Health and Nutrition Examination Survey and the National Health Interview Survey. Because data based on national population samples are unavailable for most specific rheumatic conditions, we derived estimates from published studies of smaller, defined populations. For specific conditions, the best available prevalence estimates were applied to the corresponding 2005 US population estimates from the Census Bureau, to estimate the number affected with each condition.


RESULTS
We estimated that among US adults, nearly 27 million have clinical osteoarthritis (up from the estimate of 21 million for 1995), 711,000 have polymyalgia rheumatica, 228,000 have giant cell arteritis, up to 3.0 million have had self-reported gout in the past year (up from the estimate of 2.1 million for 1995), 5.0 million have fibromyalgia, 4-10 million have carpal tunnel syndrome, 59 million have had low back pain in the past 3 months, and 30.1 million have had neck pain in the past 3 months.


CONCLUSION
Estimates for many specific rheumatic conditions rely on a few, small studies of uncertain generalizability to the US population. This report provides the best available prevalence estimates for the US, but for most specific conditions more studies generalizable to the US or addressing understudied populations are needed.

National Arthritis Data Work-group. Estimates of the prevalence of arthritis and other rheumatic conditions in the United States. Part II

Objective
To provide a single source for the best available estimates of the national prevalence of arthritis in general and of selected musculoskeletal disorders (osteoarthritis, rheumatoid arthritis, juvenile rheumatoid arthritis, the spondylarthropathies, systemic lupus erythematosus, scleroderma, polymyalgia rheumatica/giant cell arteritis, gout, fibromyalgia, and low back pain).

Methods
The National Arthritis Data Workgroup reviewed data from available surveys, such as the National Health and Nutrition Examination Survey series. For overall national estimates, we used surveys based on representative samples. Because data based on national population samples are unavailable for most specific musculoskeletal conditions, we derived data from various smaller survey samples from defined populations. Prevalence estimates from these surveys were linked to 1990 US Bureau of the Census population data to calculate national estimates. We also estimated the expected frequency of arthritis in the year 2020.

Results
Current national estimates are provided, with important caveats regarding their interpretation, for self-reported arthritis and selected conditions. An estimated 15% (40 million) of Americans had some form or arthritis in 1995. By the year 2020, an estimated 18.2% (59.4 million) will be affected.

Conclusion
Given the limitations of the data on which they are based, this report provides the best available prevalence estimates for arthritis and other rheumatic conditions overall, and for selected musculoskeletal disorders, in the US population.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/1529-0131%28199805%2941%3A5%3C778%3A%3AAID-ART4%3E3.0.CO%3B2-V

Estimates of the prevalence of arthritis and selected musculoskeletal disorders in the United States

Osteoarthritis is the most common form of arthritis, affecting millions of people in the United States. It is a complex disease whose etiology bridges biomechanics and biochemistry. Evidence is growing for the role of systemic factors (such as genetics, dietary intake, estrogen use, and bone density) and of local biomechanical factors (such as muscle weakness, obesity, and joint laxity). These risk factors are particularly important in weightbearing joints, and modifying them may present opportunities for prevention of osteoarthritis-related pain and disability. Major advances in management to reduce pain and disability are yielding a panoply of available treatments ranging from nutriceuticals to chondrocyte transplantation, new oral anti-inflammatory medications, and health education. This article is part 1 of a two-part summary of a National Institutes of Health conference. The conference brought together experts on osteoarthritis from diverse backgrounds and provided a multidisciplinary and comprehensive summary of recent advances in the prevention of osteoarthritis onset, progression, and disability. Part 1 focuses on a new understanding of what osteoarthritis is and on risk factors that predispose to disease occurrence. It concludes with a discussion of the impact of osteoarthritis on disability. Ann Intern Med. 2000;133:635-646. www.annals.org For author affiliations and current addresses, see end of text.

/pdf/osteoarthritis-new-insights-part-1-the-disease-and-its-risk-2p0wtgll5h.pdf

Osteoarthritis: New Insights Part 1: The Disease and Its Risk Factors

To investigate the prevalence of osteoarthritis (OA) of the knee in elderly subjects, we studied the Framingham Heart Study cohort, a population-based group. During the eighteenth biennial examination, we evaluated the cohort members for OA of the knee by use of medical history, physical examination, and anteroposterior (standing) radiograph of the knees. Radiographs were obtained on 1,424 of the 1,805 subjects (79%). Their ages ranged from 63-94 years (mean 73). Radiographs were read by a radiologist who specializes in bone and joint radiology, and were graded 0-4 according to the scale described by Kellgren and Lawrence. OA was defined as grade 2 changes (definite osteophytes), or higher, in either knee. Radiographic evidence of OA increased with age, from 27% in subjects younger than age 70, to 44% in subjects age 80 or older. There was a slightly higher prevalence of radiographic changes of OA in women than in men (34% versus 31%); however, there was a significantly higher proportion of women with symptomatic disease (11% of all women versus 7% of all men; P = 0.003). The age-associated increase in OA was almost entirely the result of the marked age-associated increase in the incidence of OA in the women studied. This study extends current knowledge about OA of the knee to include elderly subjects, and shows that the prevalence of knee OA increases with age throughout the elderly years.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/art.1780300811

The prevalence of knee osteoarthritis in the elderly. The Framingham Osteoarthritis Study.

Study objective To determine whether obesity preceded knee osteoarthritis and was thus a possible cause. Design Cohort study with weight and other important variables measured in 1948 to 1951 (mean age of subjects, 37 years) and knee arthritis evaluated in 1983 to 1985 (mean age of subjects, 73 years). Setting Population-based participants; a subset (n = 1420) of the Framingham Heart Study cohort. Methods For those subjects in the Framingham Study having knee radiographs taken as part of the 18th biennial examination (1983 to 1985), we examined Metropolitan Relative Weight, a measure of weight adjusted for height at the onset of the study (1948 to 1951). Relative risks were computed as the cumulative incidence rate of radiographic knee osteoarthritis in the heaviest weight groups at examination 1 divided by the cumulative rate in the lightest 60% weight groups at examination 1. Relative risks were adjusted for age, physical activity level, and uric acid level. Results In 1983 to 1985, 468 subjects (33%) had radiographic knee osteoarthritis. For men, the risk of knee osteoarthritis was increased in those in the heaviest quintile of weight at examination 1 compared with those in the lightest three quintiles (age-adjusted relative risk, 1.51; 95% confidence interval [CI], 1.14 to 1.98); risk was not increased for those in the second heaviest quintile (relative risk, 1.0). The association between weight and knee osteoarthritis was stronger in women than in men; for women in the most overweight quintile at examination 1, relative risk was 2.07 (95% CI, 1.67 to 2.55), and for those in the second heaviest group, relative risk was 1.44 (95% CI, 1.11 to 1.86). This link between obesity and subsequent osteoarthritis persisted after controlling for serum uric acid level and physical activity level, and was strongest for persons with severest radiographic disease. Obesity at examination 1 was associated with the risk of developing both symptomatic and asymptomatic osteoarthritis. Conclusions These results and other corroborative cross-sectional data show that obesity or as yet unknown factors associated with obesity cause knee osteoarthritis.

Obesity and knee osteoarthritis. The Framingham Study.

Objective To evaluate the effect of weight loss in preventing symptomatic knee osteoarthritis in women. Design Cohort analytic study. Setting The Framingham Study, based on a sample of a defined population. Patients Women who participated in the Framingham Knee Osteoarthritis Study (1983 to 1985): Sixty-four out of 796 women studied had recent-onset symptomatic knee osteoarthritis (knee symptoms plus radiographically confirmed osteoarthritis) were compared with women without disease. Measurements Recalled date of symptom onset was used as the incident date of disease. Historical weight was defined as baseline body mass index up to 12 years before symptom onset. Change in body mass index was assessed at several intervals before the current examination. Odds ratios assessing the association between weight change and knee osteoarthritis were adjusted for age, baseline body mass index, history of previous knee injury, habitual physical activity level, occupational physical labor, smoking status, and attained education. Results Weight change significantly affected the risk for the development of knee osteoarthritis. For example, a decrease in body mass index of 2 units or more (weight loss, approximately 5,1 kg) over the 10 years before the current examination decreased the odds for developing osteoarthritis by over 50% (odds ratio, 0.46; 95% Cl, 0.24 to 0.86; P = 0.02). Among those women with a high risk for osteoarthritis due to elevated baseline body mass index (greater than or equal to 25), weight loss also decreased the risk (for 2 units of body mass index, odds ratio, 0.41; P = 0.02). Weight gain was associated with a slightly increased risk for osteoarthritis, which was not statistically significant. Conclusion Weight loss reduces the risk for symptomatic knee osteoarthritis in women.

Weight loss reduces the risk for symptomatic knee osteoarthritis in women. The Framingham Study.

Objective. Knee osteoarthritis (OA) is highly prevalent, especially in the elderly. Preventive strategies require a knowledge of risk factors that precede disease onset. The present study was conducted to determine the longitudinal risk factors for knee OA in an elderly population.



Methods. A longitudinal study of knee OA involving members of the Framingham Study cohort was performed. Weight-bearing knee radiographs were obtained in 1983–1985 (baseline) and again in 1992–1993. Incident disease was defined as the occurrence of new radiographic OA (Kellgren and Lawrence grade ⩾2 on a 0–4 scale) in those without radiographic OA at baseline. Risk factors assessed at baseline and in the interim were tested in univariate and multivariate equations to evaluate their association with incident knee OA.



Results. Of 598 patients without knee OA at baseline (mean age 70.5 years, 63.7% women), 93 (15.6%) developed OA. After adjustment for multiple risk factors, women had a higher risk of OA than did men (adjusted odds ratio [OR] = 1.8, 95% confidence interval [95% CI] 1.1–3.1). Higher baseline body mass index increased the risk of OA (OR = 1.6 per 5-unit increase, 95% CI 1.2–2.2), and weight change was directly correlated with the risk of OA (OR = 1.4 per 10-lb change in weight, 95% CI 1.1–1.8). Physical activity increased the risk of OA (for those in the highest quartile, OR = 3.3, 95% CI 1.4–7.5). Smokers had a lower risk than did nonsmokers (for those who smoked an average of ⩾10 cigarettes/day, OR = 0.4, 95% CI 0.2–0.8). Factors not associated with the risk of OA included chondrocalcinosis and a history of hand OA. Weight-related factors affected the risk of OA only in women.



Conclusion. Elderly persons at high risk of developing radiographic knee OA included obese persons, nonsmokers, and those who were physically active. The direction of weight change correlated directly with the risk of developing OA.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/art.1780400420

Risk factors for incident radiographic knee osteoarthritis in the elderly. The framingham study

Objective. To determine the incidence of radiographic knee osteoarthritis (OA) and symptomatic OA (symptoms plus radiographic OA), as well as the rate of progression of preexisting radiographic OA in a population-based sample of elderly persons.

Methods. Framingham Osteoarthritis Study subjects who had knee radiographs and had answered questions about knee symptoms in 1983–1985 were reexamined in 1992–1993 (mean 8.1-year interval) using the same protocol. Subjects were defined as having new (incident) radiographic OA if they developed grade ≤2 OA (at least definite osteophytes or definite joint space narrowing). New symptomatic OA was present if subjects developed a combination of knee symptoms and grade ≤2 OA. Progressive OA was diagnosed when radiographs showing grade 2 disease at baseline showed grade ≤3 disease on followup.

Results. Of 1,438 participants in the original study, 387 (26.9%) died prior to followup. Of the 1,051 surviving subjects, 869 (82.7%) participated in the followup study (mean ± SD age 70.8 ± 5.0 at baseline). Rates of incident disease were 1.7 times higher in women than in men (95% confidence interval [CI] 1.0–2.7), and progressive disease occurred slightly more often in women (relative risk = 1.4; 95% CI 0.8–2.5) but rates did not vary by age in this sample. Among women, approximately 2% per year developed incident radiographic disease, 1% per year developed symptomatic knee OA, and about 4% per year experienced progres- sive knee OA.

Conclusion. In elderly persons, the new onset of knee OA is frequent and is more common in women than men. However, among the elederly, age may not affect new disease occurrence or progression.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/art.1780381017

Allan Naimark

Papers

The prevalence of knee osteoarthritis in the elderly. The Framingham Osteoarthritis Study.

Obesity and knee osteoarthritis. The Framingham Study.

Weight loss reduces the risk for symptomatic knee osteoarthritis in women. The Framingham Study.

Risk factors for incident radiographic knee osteoarthritis in the elderly. The framingham study

The incidence and natural history of knee osteoarthritis in the elderly, the framingham osteoarthritis study