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F Wolfe

Publications and source records attributed to F Wolfe.

At least 37 records · Page 2Linked to original sources
PubMed2000

Preference for nonsteroidal antiinflammatory drugs over acetaminophen by rheumatic disease patients: a survey of 1,799 patients with osteoarthritis, rheumatoid arthritis, and fibromyalgia.

OBJECTIVE: Because there is controversy regarding the efficacy of acetaminophen in rheumatic diseases and because apparently safer nonsteroidal antiinflammatory drugs (NSAIDs) are being produced, we surveyed rheumatic disease patients about their preferences for these agents to determine the degree to which one type of therapeutic agent is preferred over the other. METHODS: In 1998, we surveyed by mailed questionnaire 1,799 patients with osteoarthritis (OA), rheumatoid arthritis, or fibromyalgia who were participating in a long-term outcome study. Patients who had taken acetaminophen rated the effectiveness of acetaminophen, compared its effectiveness with that of NSAIDs, and then rated their overall satisfaction with acetaminophen compared with NSAIDs when both effectiveness and side effects were considered. RESULTS: Two-thirds of study participants had taken acetaminophen. About 37% of patients who had taken acetaminophen found it to be moderately or very effective and about 63% indicated that it was not effective or was only slightly effective. One-fourth of the patients found acetaminophen and NSAIDs to be equally effective, but >60% found acetaminophen to be much less effective or somewhat less effective. About 12% preferred acetaminophen to NSAIDs. When both effectiveness and side effects were considered together, 25% of the patients had no preference, 60% preferred NSAIDs, and 14% preferred acetaminophen. CONCLUSION: There was a considerable and statistically significant preference for NSAIDs compared with acetaminophen among the 3 groups of rheumatic disease patients. Although this preference decreased slightly with age and was less pronounced in OA patients, the preference was noted among all categories of patients and was not altered by disease severity. If safety and cost are not issues, there would hardly ever be a reason to recommend acetaminophen over NSAIDs, since patients generally preferred NSAIDs and fewer than 14% preferred acetaminophen. If safety and costs are issues, then the recommendation of the American College Rheumatology that acetaminophen be tried first seems correct, since 38.2% found acetaminophen to be as effective or more effective than NSAIDs.

Acetaminophen↗
PubMed2000

A reappraisal of HAQ disability in rheumatoid arthritis.

OBJECTIVE: To investigate the course of self-reported disability in rheumatoid arthritis (RA) using the major self-report measure of functional impairment, the Health Assessment Questionnaire (HAQ). METHODS: The course of HAQ disability was assessed in 32,525 observations (1,843 patients) in which the HAQ was administered. In addition, a subset of 2,189 visits from 50 patients, followed on average for 17 years, was studied to model the effect of disease duration on the course of HAQ disability in individual patients. Linear and fractional polynomial regression as well as smoothing algorithms were applied to the group of RA patients and then to the individual course of patients. RESULTS: Group linear and nonlinear models of the effect of disease duration on HAQ disability were found to have 3 characteristics: 1) HAQ disability scores are high at disease onset rather than gradually increasing; 2) HAQ disability increases very slowly over time (0.03 units per year); and 3) all such models fit very poorly, explaining only 5% of the variance in HAQ disability scores. However, application of nonlinear models to individual patient courses (as opposed to groups of patients) explains 37% of the HAQ disability score variation. In some patients, the course of HAQ disability was either 1) chaotic (scores change without any pattern) or 2) determinable, but unrelated to time. When covariates were added to the group model, however, the course of HAQ disability became clearer, and 51% of the variance in the disability score could be explained, statistically, by pain, depression, erythrocyte sedimentation rate, and disease duration. CONCLUSION: Individual RA patients have differing, characterizable courses: 1) nonlinear, 2) chaotic, or 3) non-time determined. The model that self-reported physical disability, as measured by the HAQ, occurs as a function of disease acting over time does not fit the data well and is an inadequate model. This discrepancy may also be the result of the patient's upward reappraisal of functional ability with increasing time. The predominant determinants of HAQ disability in RA are disease activity, pain, and psychosocial factors rather than structural abnormality. Although the HAQ is a useful clinical tool and a central measure of disease outcome, it measures both process and outcome, and usually more process than outcome. Individual patient models that include all that is known about the patient--the paradigm of clinical care-may be a more effective way to examine the course of RA than are conventional group-based models.

Adult↗
PubMed2000

The effect of smoking on clinical, laboratory, and radiographic status in rheumatoid arthritis.

OBJECTIVE: (1) To determine the degree to which rheumatoid factor (RF) positivity is associated with smoking; (2) to determine the quantitative effect of smoking and smoking length on the concentration of RF in all patients, and, in the seropositive patients separately, determining if a "dose-response" effect exists; (3) to investigate these relationships in men and women to clarify whether the effect of smoking is similar in both sexes; (4) to determine the effect of smoking, controlling for RF, on a variety of measures of disease status, severity, and activity. METHODS: Six hundred ten consecutive patients with rheumatoid arthritis seen for routine clinical care provided information on their smoking history. All underwent a complete joint examination, completed a series of health status questionnaires, provided information concerning pulmonary illnesses, underwent determinations for RF and erythrocyte sedimentation rate (ESR), and had hand radiographs. RESULTS: RF concentration was linearly related to the number of years smoked. This association was present in both sexes, but was stronger in men. Smoking was similarly related to rheumatoid nodule formation. A nonlinear relationship was found between smoking and radiographic abnormalities as determined by the Larsen method, even controlling for RF. Similarly, pulmonary illness was independently related to smoking and RF. No effect of smoking was seen on disease process variables such as ESR, pain, joint count, global severity, or functional ability. CONCLUSION: Quantitative relationships exist between smoking extent and RF positivity, RF concentration, nodule formation, radiographic progression, and pulmonary disease. These 3 latter effects are independent of RF positivity or concentration. Smoking does not contribute to alterations in disease activity measures, but appears to play a role in overall severity of disease.

Aged↗
PubMed2000

Modeling therapeutic strategies in rheumatoid arthritis: use of decision analysis and Markov models.

OBJECTIVE: The management of patients with rheumatoid arthritis (RA) is controversial, with a number of different proposed treatment strategies based on different conceptions of the natural history of the disease and different interpretations of the efficacy and effectiveness of the drugs used for treatment. We attempted to develop a theoretical framework to assess the effectiveness of different treatment regimens for RA. METHODS: We used decision analysis to structure the problem of comparing sequential monotherapy to a combination strategy. Subsequently, we used 3 different estimates of drug effectiveness: one from expert rheumatologists; a metaanalysis; and a recent nationwide survey of American rheumatologists, in a Markov model. Last, we utilized published duration of therapy data to model drug treatment over time. RESULTS: Estimates of drug effectiveness differed substantially among rheumatologists, but regardless of the estimates and the treatment strategy used, the model predicted over 90% of patients improved by the 3rd drug trial. Over time, treatment patterns in our model resemble the "sawtooth" pattern previously observed. CONCLUSION: Treatment strategies in RA are difficult to model because of uncertainty in both the structure of the model and the data needed to perform the analysis. These models tend to overestimate the effectiveness of drug sequences because of nonindependence between therapies, probably due to sequence effects, a change in responsiveness over time, or resistant subgroups. Our preliminary analysis suggests that the most effective agent, possibly methotrexate, should be used first if the objective is to get as many patients into remission as quickly as possible.

Arthritis, Rheumatoid↗
PubMed2000

Gastrointestinal symptoms and health related quality of life in patients with arthritis.

OBJECTIVE: To evaluate the relationship between gastrointestinal (GI) symptoms and health related quality of life (QOL) in patients with osteoarthritis (OA) and rheumatoid arthritis (RA). METHODS: A total of 1773 patients with arthritis participating in a longterm outcome study (OA of the hip or knee = 648, RA = 1125) completed mailed surveys that included assessments of GI symptoms and overall GI symptom severity, Short Form-36, the visual analog scale (VAS) for the EuroQol (Health QOL), a VAS global disease severity scale, and measures of disease and psychological status. The overall response rate exceeded 85%. RESULTS: Dyspepsia (heartburn, bloating, or belching) and upper abdominal/epigastric pain were identified as the most important GI contributors to reduction in QOL, and the simultaneous presence of both these symptoms was associated with lower QOL (54.5) compared to those without symptoms (70.9) on the 0-100 Health QOL scale. Similarly, those in the upper tertile of the global GI severity scale had Health QOL scores of 55.7 compared to 76.4 for those in the lower tertile. These differences in GI symptoms and GI severity, however, were reduced substantially when the effects of functional disability, pain, and depression were adjusted for: 62.3 to 68.6 (p = 0.003) and 63.7 to 70.3 (p<0.001) for the GI symptoms and GI severity scales, respectively. CONCLUSION: QOL is significantly impaired among unselected arthritis patients with GI symptoms compared to those without these symptoms. Dyspepsia and upper abdominal/epigastric pain are more strongly related to QOL measures than other GI symptoms, and are common among arthritis patients. It is possible to construct a simple scale of these 2 symptoms or to use the VAS GI severity scale and get a clinically useful idea of the current level of GI distress and alteration of QOL by GI problems. Two components of impairment can be identified, one that is smaller and unrelated to disease or psychological factors, and a second that is larger and includes these factors. Because GI symptoms can alter function, pain, and psychological status, it is likely that the true effect of GI symptoms on QOL is somewhere between the unadjusted and adjusted values cited above.

Adult↗
PubMed2000

The importance of gastrointestinal (GI) symptom severity in rheumatoid and osteoarthritis: symptom rates and risk for GI hospitalization.

OBJECTIVE: To determine the prevalence and stability of gastrointestinal (GI) symptoms in outpatients with rheumatoid arthritis (RA) and osteoarthritis (OA); to determine the specific symptoms that contribute to severity; and to determine the predictive value of GI symptoms and GI severity on the risk of future GI hospitalization. METHODS: A questionnaire survey was mailed to 1221 patients with RA and OA on a continuing 6 month schedule. Patients completed an average of 4.4 questionnaires (n = 5,047). Questionnaires included a visual analog scale GI severity scale, and questions regarding GI hospitalizations and specific GI symptoms. Hospitalizations that were reported as relating to the GI system were audited by checking hospital records. RESULTS: We found 57.5%, 40.2%, and 25.5% of patients had at least one assessment in which they had a GI symptom severity of 0.25-0.99, 1.00-1.99, and 2.00 or greater, respectively. Overall 74.9% had at least one score of 0.25 or greater, and 73.6% had one score of < 0.25, the cutoff for GI symptoms. By contrast, 6.45% had a GI hospitalization, and in only 0.75% of the questionnaire assessments were hospitalizations noted. Pyrosis and peptic ulcer symptoms were common, and were found in 62.5% and 42.4% of patients and 28.2% and 12.9% of observations, respectively. Among patients reporting GI severity scores between 2 and 3, roughly 60% and 45% reported the presence of pyrosis and peptic ulcer symptoms, respectively. The presence of a GI severity score > or = 0.25 was associated with 2.8-3.0-fold increase in the risk of hospitalization over the following 6 months. CONCLUSION: These data suggest that symptoms have an importance of their own that relates to quality of life, regardless of the risk of serious GI events like hospitalization, and that more attention should be placed on symptoms and symptom severity in future research. In spite of the statistical predictive value of GI symptom severity on future hospitalizations, it is important to recognize that rate of GI hospitalization increases from 0.92 per 100 patient-years to only 2.90 per 100 patient-years when the GI symptom scale goes from approximately zero to positive values. Thus, in spite of its statistical predictive ability, GI symptom severity is a poor clinical predictor of the hospitalizations that occur in patients with rheumatic diseases. Instead, GI symptom severity and specific GI symptoms have a separate importance to patients.

Arthritis, Rheumatoid↗
PubMed2000

The comparative risk and predictors of adverse gastrointestinal events in rheumatoid arthritis and osteoarthritis: a prospective 13 year study of 2131 patients.

OBJECTIVE: It has been suggested that rheumatoid arthritis (RA) itself may be a risk factor for adverse gastrointestinal (GI) events, but this hypothesis has not been studied in a large sample, nor has the effect of time on risk factors been studied. We investigated rates and risk factors for GI events in RA and osteoarthritis (OA) and assessed the additional risks conveyed by having RA. METHODS: A prospective study of patients with OA and RA from a single center was undertaken using questionnaires mailed at 6 month intervals. The relationship between drug therapy and GI events was assessed in the same 6 month time frame. Over 13 years of biannual assessments, 2,131 patients were studied for serious GI events and adverse GI symptoms during 9,621 patient-years of observation. RESULTS: The incidence rate (IR) for GI hospitalization was 1.56 and 1.28 per 100 patient-years, and for GI bleeding or perforation was 0.50 and 0.58 for RA and OA, respectively. After controlling for age, sex, nonsteroidal antiinflammatory drug (NSAID) and steroid use, the incidence rate ratio (IRR) for RA versus OA did not differ for hospitalization [IRR 1.07 (95% CI 0.66, 1.74)] or for bleeding or perforation [IRR 0.63 (95% CI 0.29, 1.35)]. In multivariate analyses for both groups combined, the IRR was 2.95 (2.05, 4.24) for prednisone use, 1.41 (1.08, 1.85) for NSAID use, and 1.46 (1.22, 1.74) for every 10 year increase in age. In additional multivariate models, Health Assessment Questionnaire disability was also a significant risk factor. During the study period, the odds of NSAID use decreased 2.94 times per 10 year period, while the odds of prednisone use increased by 1.49. Dysphagia [IRR 1.11 (1.00, 1.24)], anorexia [IRR 1.13 (1.03, 1.23)], nausea [IRR 1.13 (1.04, 1.25)], heartburn [IRR 1.12 (1.05, 1.19)], vomiting [IRR 1.20 (1.02, 1.42)], peptic ulcer symptoms [IRR 1.20 (1.11, 1.29)], and abdominal pain [IRR 1.11 (1.01, 1.22)] were associated with NSAID use, but not with steroids. CONCLUSION: Patients with RA and OA do not differ in the rates and risk factors for GI hospitalizations and symptoms after controlling for age, steroid use, NSAID use, or (for OA) body mass index. Prednisone is a more important risk factor among patients with RA than NSAID.

Adrenal Cortex Hormones↗
PubMed2000

The assessment of functional impairment in fibromyalgia (FM): Rasch analyses of 5 functional scales and the development of the FM Health Assessment Questionnaire.

OBJECTIVE: Functional assessment by self-report questionnaire plays an important role in most rheumatic conditions, but psychometric properties of questionnaires have not been studied in fibromyalgia (FM), particularly by Rasch analysis, which allows for examining adequacy of the questionnaire scale. To assess currently used instruments, we examined the Fibromyalgia Impact Scale (FIQ), 4 versions of the Health Assessment Questionnaire (HAQ), and the Medical Outcome Survey Short Form (SF-36). METHODS: More than 2,500 patients from 4 sites (3 US, 1 Israel) completed the FIQ. The HAQ questionnaires were completed by 1438 patients participating in the US National Data Bank for Rheumatic Diseases. Seven hundred sixty patients from Wichita, Kansas, completed the SF-36. Rasch analysis was applied separately to each of these data sets. RESULTS: The FIQ systematically underestimated functional impairment by its handling of activities not usually performed. All questionnaires had problems with non-unidimensionality and ambiguous items when applied to patients with FM. In addition, scales were found to be non-linear. Because of these findings we used the 20 item HAQ questionnaire as an item bank to develop a new questionnaire more suitable for use in FM, the fibromyalgia HAQ (FHAQ). This questionnaire fits the Rasch model well, is relevant, is linear, and has a long, well spaced scale. CONCLUSION: No available functional assessment questionnaire works well in FM. A new questionnaire, the FHAQ, was developed. It has appropriate metric properties and should function well in this condition. Since the FHAQ is a subset of the larger HAQ questionnaire, a new questionnaire is not required; only a different method of scoring is needed. Additional studies regarding sensitivity to change are required to fully validate the FHAQ.

Disability Evaluation↗
PubMed2000

Measuring the epidemiology of distress: the rheumatology distress index.

OBJECTIVES: (1) To examine clinical and psychological variables to determine which are associated with psychologic and psychosocial severity or "distress"; (2) to investigate whether patients with the 2 major rheumatic disorders, rheumatoid arthritis (RA) and osteoarthritis (OA), differ in distress variables and distress; and (3) to develop and validate a simple, clinically acceptable index of distress suitable for routine care and research purposes. METHODS: A total of 2,403 patients were evaluated in 2 data sets (N = 1,399 and N = 1,490). The first data set was evaluated in the clinic by a routine clinical examination and administration of the Clinical Health Assessment Questionnaire (CLINHAQ). This instrument includes measures of pain, global severity, functional disability, anxiety, depression, sleep disturbance, fatigue, health satisfaction, and health status. The second data set was evaluated by a mailed questionnaire that included the CLINHAQ, but also coping scales, the Beliefs in Pain Control Questionnaire, the Self Performance Scale, and the Arthritis Helplessness Index. RESULTS: RA and OA groups had similar scores for the variables associated with distress: pain, global severity, functional disability, anxiety, depression, sleep disturbance, fatigue, health satisfaction, and health status. Patients with fibromyalgia (FM) had more abnormal scores for every variable, reflecting overall distress. Using patients with FM as a "gold standard" of distress, we developed an index in data set 2. the Rheumatology Distress Index (RDI), made up of 5 variables, anxiety, depression, global severity, fatigue, and sleep disturbance, that best identified patients with FM compared to other patients. We then validated the instrument on the distress severity clusters formed in data set 1. The correlation between RDI and distress severity cluster was 0.874 with all patients considered and 0.867 with FM patients excluded. In addition, RDI predicted 1,174 of 1,399 (83.9%) cluster memberships correctly. Compared with a battery of psychological and clinical tests that classified 74% of FM and non-FM patients correctly, the RDI and is only slightly less effective, classifying 70.3% correctly. CONCLUSION: Distress is a patient rather than a disease phenomenon. A simple, easy to administer self-report questionnaire can be used to classify patients according to their level of distress. The resulting index, the RDI. accurately identifies distressed and non-distressed patients. Such an index should be useful for patient care and research.

Aged↗
PubMed2000

Assessing radiographic status of rheumatoid arthritis: introduction of a short erosion scale.

OBJECTIVE: Although radiographs are an important marker of rheumatoid arthritis severity, no valid simple scoring method exists. Current scoring systems are cumbersome, difficult to learn, time consuming, and suitable only for experts. In addition, there is no "gold standard" for radiographic severity, so that it is impossible for the clinician, trialist, or researcher to place patients' scores along a continuum of radiographic severity. We investigated the scoring and scaling properties of radiographs read by the Larsen method, and we developed a shortened scale that can be placed in the perspective of a linear severity continuum. METHODS: A total of 3,538 paired hand radiographs obtained over a 24 year period were read by Larsen method and evaluated by Rasch analysis. By iterative methods the number of joints was reduced so that proper fitting, scaling, and dimensionality were obtained. The shortened scale was then tested against the full Larsen scale to determine its ability to detect radiographic progression. RESULTS: A scale consisting of 6 joints on each hand (3 wrist areas and 3 metacarpophalangeal joints) performed as well as the full 28 joint Larsen score, and had improved fit and scaling properties. This Short Erosion Scale (SES) also performed as well as the Larsen score in measuring radiographic progression as measured by comparative effect sizes. In addition, a nomogram was developed to translate SES scores into radiographic severity scores according to a Rasch logit scale. CONCLUSION: We developed a Short Erosion Scale by reducing the number of joints evaluated in the Larsen method from 28 to 12. The scale is at least as sensitive in detecting change as the full Larsen scale. SES fits the Rasch model and is hierarchical and generally well spaced. Graphs and nomograms are available so that intrinsic radiographic severity can be documented. This scale is suitable for use in clinical practice and observational studies, and may be appropriate for clinical trials as well.

Arthritis, Rheumatoid↗
PubMed1999

Toward a multidimensional Health Assessment Questionnaire (MDHAQ): assessment of advanced activities of daily living and psychological status in the patient-friendly health assessment questionnaire format.

OBJECTIVE: To develop components of a multidimensional Health Assessment Questionnaire (MDHAQ) through the addition of new items in the "patient-friendly" HAQ format, including advanced activities of daily living (ADL), designed to overcome "floor effects" of the HAQ and modified HAQ (MHAQ) in which patients may report normal scores although they experience meaningful functional limitations, and psychological items, designed to screen efficiently for psychological distress in routine care. METHODS: The new MDHAQ items, as well as scales for pain, fatigue, helplessness, and global health status on a 2-page questionnaire, were completed by 688 consecutive patients with various rheumatic diseases, including 162 with rheumatoid arthritis (RA), 114 with fibromyalgia, 63 with osteoarthritis, 34 with systemic lupus erythematosus, 20 with vasculitis, 18 with psoriatic arthritis, 16 with scleroderma, and 261 with various other rheumatic diseases, over 2 years at a weekly academic rheumatology clinic. RESULTS: The new MDHAQ items have good test-retest reliability and face validity. MHAQ scores were highest in patients with RA, and scores for other scales were highest in patients with fibromyalgia. On the advanced ADL, 58% of patients reported difficulty with errands, 68% with climbing stairs, 79% with walking two miles, 87% with participating in sports and games, and 94% with running or jogging two miles. On the psychological items, 75% of patients reported difficulty with sleep, 63% with stress, 61% with anxiety, and 57% with depression. Normal MHAQ scores were reported by 23% of patients and normal HAQ scores by 16% of patients who completed these questionnaires, while fewer than 5% had normal scores on the MDHAQ. CONCLUSION: The MDHAQ items overcome in large part the "floor effects" seen on the HAQ and MHAQ, and are useful to screen for problems with sleep, stress, anxiety, and depression in the "patient-friendly" HAQ format. These data support the value of completion of a simple 2-page patient questionnaire by each patient at each visit to a rheumatologist.

Female↗
PubMed1999

Psychological distress and rheumatic disease.

Psychological factors influence the results of self-reports of pain, function and global severity in questionnaires such as the HAQ, SF-36 and the WOMAC. Persons with psychological distress use more resources, including medications, and have greater rates of work disability and joint surgery. Psychological status is influenced only very slightly by disease severity and tends to remain relatively constant over the course of the rheumatic disease. The psychological status of patients with differing rheumatic diseases is similar, and patients with rheumatoid arthritis do not have special psychological problems or psychological characteristics.

Arthritis↗
PubMed1999

Determinants of WOMAC function, pain and stiffness scores: evidence for the role of low back pain, symptom counts, fatigue and depression in osteoarthritis, rheumatoid arthritis and fibromyalgia.

OBJECTIVES: The Western Ontario MacMaster (WOMAC) is a validated instrument designed specifically for the assessment of lower extremity pain and function in osteoarthritis (OA) of the knee or hip. In the clinic, however, we have noted that OA patients frequently have other musculoskeletal and non-musculoskeletal problems that might contribute to the total level of pain and functional abnormality that is measured by the WOMAC. In this report, we investigated back pain and non-articular factors that might explain WOMAC scores in patients with OA, rheumatoid arthritis (RA) and fibromyalgia (FM) in order to understand the specificity of this instrument. METHODS: RA, OA and FM patients participating in long-term outcomes studies completed the WOMAC and were assessed for low back pain, fatigue, depression and rheumatic disease symptoms by mailed questionnaires. RESULTS: Regardless of diagnosis, WOMAC functional and pain scores were very much higher (abnormal) among those complaining of back pain. On average, WOMAC scores for back pain (+) patients exceeded those of back pain (-) patients by approximately 65%,, and 52% of OA patients reported back pain. In regression analyses, study symptom variables explained 42, 44 and 38% of the variance in WOMAC function, pain and stiffness scores, respectively. In the subset of OA patients, radiographic scores added little to the explained variance. The strongest predictor of WOMAC abnormality in bivariate and multivariate analyses was the fatigue score, with correlations of 0.58, 0.60 and 0.53 with WOMAC function, pain and stiffness, respectively. The WOMAC performed well in RA and FM, and correlated strongly with the Health Assessment Questionnaire (HAQ) disability scale and a visual analogue scale (VAS) pain scale. CONCLUSION: The WOMAC captures more than just knee or hip pain and dysfunction, and is clearly influenced by the presence of fatigue, symptom counts, depression and low back pain. WOMAC scores also appear to reflect psychological and constitutional status. These observations suggest the need for care in interpreting WOMAC scores as just a measure of function, pain or stiffness, and indicate the considerable importance of psychological factors in rheumatic disease and rheumatic disease assessments.

Adult↗
PubMed1999

Rasch analysis of the Western Ontario MacMaster questionnaire (WOMAC) in 2205 patients with osteoarthritis, rheumatoid arthritis, and fibromyalgia.

OBJECTIVE: Advances in health measurement have led to the application of Rasch Item Response Theory (IRT) analysis (Rasch analysis) to evaluate instruments measuring health status and quality of life of patients, including the Health Assessment Questionnaire and SF-36. This study investigated the extent to which the Western Ontario MacMaster osteoarthritis questionnaire (WOMAC) satisfies the Rasch model, particularly in respect to unidimensionality, item separation, and linearity. METHODS: The study included a total of 2205 patients, 1013 with rheumatoid arthritis (RA), 655 with osteoarthritis of the knee or hip (OA), and 537 with fibromyalgia. All patients completed the WOMAC as part of a longitudinal study of rheumatic disease outcomes. To examine whether the WOMAC pain and function scales each fits the Rasch model, the Winsteps program was used to assess item difficulty, scale unidimensionality, item separation, and linearity. RESULTS: Although the WOMAC worked best in OA, regardless of disorder, both the pain and function scales were unidimensional, had adequate item separation, and had a long range (25-150) of linearity in the function scale. Several functional items, however, had a high information weight fit (INFIT) statistic, indicating poor fit to the model. These items included "getting in and out of the bath" and "going down stairs." CONCLUSION: The WOMAC generally satisfies the requirements of Rasch item response theory across all disorders studied, and is an appropriate measure of lower body function in OA, RA and fibromyalgia. Although some individual items do not fit well, it is not likely that removing such items would result in more than overall minimal differences, and it will be difficult to remove traces of multidimensionality while keeping the central constructs of progressive lower body musculoskeletal abnormality intact. In addition, it is possible that a "purer", still more unidimensional instrument would be less useful in clinical trials and epidemiological studies by restricting the range of the scale.

Activities of Daily Living↗