Frederick Wolfe

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 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.

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

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 of 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.

The American College of Rheumatology Preliminary Diagnostic Criteria for Fibromyalgia and Measurement of Symptom Severity

To develop simple, practical criteria for clinical diagnosis of fibromyalgia that are suitable for use in primary and specialty care and that do not require a tender point examination, and to provide a severity scale for characteristic fibromyalgia symptoms.

American College of Rheumatology/European League Against Rheumatism Provisional Definition of Remission in Rheumatoid Arthritis for Clinical Trials

OBJECTIVE Remission in rheumatoid arthritis (RA) is an increasingly attainable goal, but there is no widely used definition of remission that is stringent but achievable and could be applied uniformly as an outcome measure in clinical trials. This work was undertaken to develop such a definition. METHODS A committee consisting of members of the American College of Rheumatology, the European League Against Rheumatism, and the Outcome Measures in Rheumatology Initiative met to guide the process and review prespecified analyses from RA clinical trials. The committee requested a stringent definition (little, if any, active disease) and decided to use core set measures including, as a minimum, joint counts and levels of an acute-phase reactant to define remission. Members were surveyed to select the level of each core set measure that would be consistent with remission. Candidate definitions of remission were tested, including those that constituted a number of individual measures of remission (Boolean approach) as well as definitions using disease activity indexes. To select a definition of remission, trial data were analyzed to examine the added contribution of patient-reported outcomes and the ability of candidate measures to predict later good radiographic and functional outcomes. RESULTS Survey results for the definition of remission suggested indexes at published thresholds and a count of core set measures, with each measure scored as 1 or less (e.g., tender and swollen joint counts, C-reactive protein [CRP] level, and global assessments on a 0-10 scale). Analyses suggested the need to include a patient-reported measure. Examination of 2-year followup data suggested that many candidate definitions performed comparably in terms of predicting later good radiographic and functional outcomes, although 28-joint Disease Activity Score-based measures of remission did not predict good radiographic outcomes as well as the other candidate definitions did. Given these and other considerations, we propose that a patients RA can be defined as being in remission based on one of two definitions: (a) when scores on the tender joint count, swollen joint count, CRP (in mg/dl), and patient global assessment (0-10 scale) are all ≤ 1, or (b) when the score on the Simplified Disease Activity Index is ≤ 3.3. CONCLUSION We propose two new definitions of remission, both of which can be uniformly applied and widely used in RA clinical trials. We recommend that one of these be selected as an outcome measure in each trial and that the results on both be reported for each trial.

Fibromyalgia Criteria and Severity Scales for Clinical and Epidemiological Studies: A Modification of the ACR Preliminary Diagnostic Criteria for Fibromyalgia

Objective. To develop a fibromyalgia (FM) survey questionnaire for epidemiologic and clinical studies using a modification of the 2010 American College of Rheumatology Preliminary Diagnostic Criteria for Fibromyalgia (ACR 2010). We also created a new FM symptom scale to further characterize FM severity. Methods. The ACR 2010 consists of 2 scales, the Widespread Pain Index (WPI) and the Symptom Severity (SS) scale. We modified these ACR 2010 criteria by eliminating the physician’s estimate of the extent of somatic symptoms and substituting the sum of 3 specific self-reported symptoms. We also created a 0–31 FM Symptom scale (FS) by adding the WPI to the modified SS scale. We administered the questionnaire to 729 patients previously diagnosed with FM, 845 with osteoarthritis (OA) or with other noninflammatory rheumatic conditions, 439 with systemic lupus erythematosus (SLE), and 5210 with rheumatoid arthritis (RA). Results. The modified ACR 2010 criteria were satisfied by 60% with a prior diagnosis of FM, 21.1% with RA, 16.8% with OA, and 36.7% with SLE. The criteria properly identified diagnostic groups based on FM severity variables. An FS score ≥ 13 best separated criteria+ and criteria− patients, classifying 93.0% correctly, with a sensitivity of 96.6% and a specificity of 91.8% in the study population. Conclusion. A modification to the ACR 2010 criteria will allow their use in epidemiologic and clinical studies without the requirement for an examiner. The criteria are simple to use and administer, but they are not to be used for self-diagnosis. The FS may have wide utility beyond the bounds of FM, including substitution for widespread pain in epidemiological studies.

Replication of Putative Candidate-Gene Associations with Rheumatoid Arthritis in >4,000 Samples from North America and Sweden: Association of Susceptibility with PTPN22, CTLA4, and PADI4

Candidate-gene association studies in rheumatoid arthritis (RA) have lead to encouraging yet apparently inconsistent results. One explanation for the inconsistency is insufficient power to detect modest effects in the context of a low prior probability of a true effect. To overcome this limitation, we selected alleles with an increased probability of a disease association, on the basis of a review of the literature on RA and other autoimmune diseases, and tested them for association with RA susceptibility in a sample collection powered to detect modest genetic effects. We tested 17 alleles from 14 genes in 2,370 RA cases and 1,757 controls from the North American Rheumatoid Arthritis Consortium (NARAC) and the Swedish Epidemiological Investigation of Rheumatoid Arthritis (EIRA) collections. We found strong evidence of an association of PTPN22 with the development of anti-citrulline antibody-positive RA (odds ratio [OR] 1.49; P=.00002), using previously untested EIRA samples. We provide support for an association of CTLA4 (CT60 allele, OR 1.23; P=.001) and PADI4 (PADI4_94, OR 1.24; P=.001) with the development of RA, but only in the NARAC cohort. The CTLA4 association is stronger in patients with RA from both cohorts who are seropositive for anti-citrulline antibodies (P=.0006). Exploration of our data set with clinically relevant subsets of RA reveals that PTPN22 is associated with an earlier age at disease onset (P=.004) and that PTPN22 has a stronger effect in males than in females (P=.03). A meta-analysis failed to demonstrate an association of the remaining alleles with RA susceptibility, suggesting that the previously published associations may represent false-positive results. Given the strong statistical power to replicate a true-positive association in this study, our results provide support for PTPN22, CTLA4, and PADI4 as RA susceptibility genes and demonstrate novel associations with clinically relevant subsets of RA.

The relation between tender points and fibromyalgia symptom variables: evidence that fibromyalgia is not a discrete disorder in the clinic

OBJECTIVE To investigate the relation between measures of pain threshold and symptoms of distress to determine if fibromyalgia is a discrete construct/disorder in the clinic. METHODS 627 patients seen at an outpatient rheumatology centre from 1993 to 1996 underwent tender point and dolorimetry examinations. All completed the assessment scales for fatigue, sleep disturbance, anxiety, depression, global severity, pain, functional disability, and a composite measure of distress constructed from scores of sleep disturbance, fatigue, anxiety, depression, and global severity—the rheumatology distress index (RDI). RESULTS In regression analyses, the RDI was linearly related to the count of tender points (r 2=0.30). Lesser associations were found between the RDI and dolorimetry measurements (r 2=0.08). The RDI was more strongly correlated with the two measures of pain threshold than any of the individual fibromyalgia symptom variables. In partial correlation analyses, all of the information relating to symptom variables was contained in the tender point count, and dolorimetry was not independently related to symptoms. CONCLUSION Tender points are linearly related to fibromyalgia variables and distress, and there is no discrete enhancement or perturbation of fibromyalgia or distress variables associated with very high levels of tender points. Although fibromyalgia is a recognisable clinical entity, there seems to be no rationale for treating fibromyalgia as a discrete disorder, and it would seem appropriate to consider the entire range of tenderness and distress in clinic patients as well as in research studies. The tender point count functions as a ‘sedimentation rate’ for distress, and is a better measure than the dolorimetry score.

Radiographic outcome of recent-onset rheumatoid arthritis: a 19-year study of radiographic progression.

OBJECTIVE To describe the longitudinal radiographic course of rheumatoid arthritis (RA), and to identify and quantitate predictors of radiographic progression. METHODS This prospective, longitudinal study of radiographic progression and clinical predictors of RA involved 256 patients with RA who were seen within the first 2 years of disease (mean 0.77 years) and were followed up for up to 19 years. Participants underwent a total of 6,278 clinical assessments (mean 24.5) and 934 paired radiographs (mean 3.1, range 2-6). Clinical assessments at every visit included determination of the erythrocyte sedimentation rate (ESR), grip strength, pain scores, tender joint counts, and anxiety and depression measurements. Regression analyses utilized time-integrated predictors. RESULTS Overall, radiographic progression rates, as measured by the summary Sharp scores, appeared constant over the course of RA. The strongest correlate of progression was the time-integrated ESR (rho=0.53). This association grew stronger with time. At 0-5 years, 5-10 years, 10-15 years, and 15-20 years, correlations were 0.40, 0.50, 0.65, and 0.74, respectively, and for the period 10-20 years, the correlation was 0.67. In multivariate models, the mean ESR, mean grip strength, rheumatoid factor positivity, and tender joint count were independent predictors of radiographic progression. CONCLUSION Radiographic damage occurs at a constant rate in RA, and is not greater early in RA or reduced later in the course of the illness. Acute-phase reactants are, by far, the strongest determinants of progression.

The long-term outcomes of rheumatoid arthritis: A 23-year prospective, longitudinal study of total joint replacement and its predictors in 1,600 patients with rheumatoid arthritis

OBJECTIVE Although total joint arthroplasty (TJA) is a common procedure and an important outcome in rheumatoid arthritis (RA), little is known about its prevalence, failure rate, or predictors over the course of the illness. The current study evaluated these factors in 1,600 consecutive RA patients seen during a period of observation that extended 23 years. METHODS Beginning in 1974, data from 34,040 RA patient visits were entered prospectively into a computer databank. Data consisted of laboratory, radiographic, physical examination, and self-report questionnaires. At each assessment, we also noted a complete surgical history. Patients were also followed up by questionnaires that were mailed at 6-month intervals. RESULTS Kaplan-Meier life-table estimates indicated that 25% of RA patients will undergo total joint arthroplasty (TJA) within 21.8 years of disease onset. For patients with 1 TJA, 25% had a TJA in a different joint within 0.92 years and 50% within 7.0 years. Ten years after TJA, approximately 6% of implanted knees and 4% of implanted hips had been replaced with a second TJA, and 12% and 13% of the joints had either a second TJA or a TJA-related operation, respectively. In Cox regressions, a large series of clinical and laboratory variables, which primarily reflected disease activity, predicted TJA. Smoking, either past or present, had a protective effect. Patients with highly abnormal values on the Health Assessment Questionnaire Disability Scale, global severity, and erythrocyte sedimentation rate had a 3-6 times increased risk of TJA. CONCLUSION TJA, a marker of joint failure and of RA outcome, is predicted by self-report assessments of severity and function, and by a series of laboratory, radiographic, and clinical variables. Prediction improves with the extent of observation, and 2-year observations approach full-study observations in their accuracy. Most TJAs survive for a long time in RA.

The global burden of rheumatoid arthritis: estimates from the Global Burden of Disease 2010 study

Objectives To estimate the global burden of rheumatoid arthritis (RA), as part of the Global Burden of Disease 2010 study of 291 conditions and how the burden of RA compares with other conditions. Methods The optimum case definition of RA for the study was the American College of Rheumatology 1987 criteria. A series of systematic reviews were conducted to gather age-sex-specific epidemiological data for RA prevalence, incidence and mortality. Cause-specific mortality data were also included. Data were entered into DisMod-MR, a tool to pool available data, making use of study-level covariates to adjust for country, region and super-region random effects to estimate prevalence for every country and over time. The epidemiological data, in addition to disability weights, were used to calculate years of life lived with disability (YLDs). YLDs were added to the years of life lost due to premature mortality to estimate the overall burden (disability-adjusted life years (DALYs)) for RA for the years 1990, 2005 and 2010. Results The global prevalence of RA was 0.24% (95% CI 0.23% to 0.25%), with no discernible change from 1990 to 2010. DALYs increased from 3.3 million (M) (95% CI 2.6 M to 4.1 M) in 1990 to 4.8 M (95% CI 3.7 M to 6.1 M) in 2010. This increase was due to a growth in population and increase in aging. Globally, of the 291 conditions studied, RA was ranked as the 42nd highest contributor to global disability, just below malaria and just above iodine deficiency (measured in YLDs). Conclusions RA continues to cause modest global disability, with severe consequences in the individuals affected.