Physical function in ankylosing spondylitis is independently determined by both disease activity and radiographic damage of the spine.

AIM: To study the relationship between disease activity, radiographic damage and physical function in patients with ankylosing spondylitis (AS) PATIENTS AND METHODS: Baseline and 2-year data of the Outcome in Ankylosing Spondylitis International Study (OASIS)(217 patients) were used. Physical function was expressed by the Bath Ankylosing Spondylitis Functional Index (BASFI) and the Dougados Functional Index (DFI); disease activity by the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and by erythrocyte sedimentation rate and C-reactive protein; and structural damage by the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS). Syndesmophyte- and non-syndesmophyte sum cores, and numbers of affected (bridged) vertebral units were derived from the mSASSS. Univariate correlations were calculated on baseline values using the Spearman rank correlation. Multivariate associations were investigated by generalised estimating equations (GEE) on baseline and 2-year data. RESULTS: mSASSS correlated moderately well with BASFI (Spearman's r = 0.45) and DFI (r = 0.38). BASDAI correlated well with BASFI (r = 0.66) and DFI (r = 0.59). Correlation coefficients for mSASSS versus BASFI and DFI decreased by increasing levels of BASDAI, being zero at the highest quintile of BASDAI. GEE showed that both BASDAI and mSASSS independently and significantly helped to explain either BASFI or DFI. Results were similar for syndesmophyte sum score, non-syndesmophyte sum score, number of affected VUs or number of VUs with bridging. The lumbar part of the mSASSS contributed similarly to the cervical part in explaining BASFI/DFI. CONCLUSION: Physical function impairment in AS is independently caused by patient-reported disease activity and the level of structural damage of the lumbar and cervical spine. Syndesmophytes and other radiographic abnormalities contribute to physical function impairment.

[Atypical tuberculous osteomyelitis of the humeral shaft caused by Mycobacterium avium]. / Atypische tuberculeuze osteomyelitis van de humerusschacht door Mycobacterium avium.

A 41-year-old man underwent skeletal scintigraphy due to chronic pain in the left foot and polyarthralgia. He was taking medication for gout and had previously had sarcoidosis, for which he had received corticosteroids and other therapy that was discontinued 4 years ago. Scintigraphy revealed a mass in the shaft of the left humerus that, according to biopsy, was an asymptomatic osteomyelitis caused by Mycobacterium avium. The shaft of the left humerus is an uncommon site for tuberculous osteomyelitis. A viable fistula remained after the biopsy that persisted despite pharmacologic treatment with ethambutol, rifabutin and clarithromycin. Four months later, sequestrectomy was performed with insertion of gentamicin-impregnated beads, which resulted in rapid resolution. The foot pain resolved spontaneously. The incidence of bone tuberculosis has increased over the last 2 decades. The most commonly affected sites are the spine and large joints. Infection with M. avium is sometimes involved. Because of the increasing incidence it is important to include mycobacterial infections in the differential diagnosis of focal bone lesions, especially when standard cultures are initially negative.

[Two patients with joint pain as initial presentation of a haematological malignancy]. / Twee patiënten met gewrichtsklachten als initiële presentatie van een hematologische maligniteit.

A 75-year-old man and a 53-year-old woman had longstanding joint pain, for which they had been treated with NSAIDs. When the symptoms worsened, a thorough diagnostic investigation was conducted that revealed myeloproliferative bone-marrow disorders in both patients. The man, who had polyarticular gout secondary to chronic myelomonocytic leukaemia, was able to maintain control of his joint pain with medical treatment. In the woman, with a history of stable joint pain due to polyarthritis, deterioration of the symptoms and the development of pancytopaenia led to a diagnosis of acute lymphocytic leukaemia; she died after receiving multiple courses of chemotherapy. The possibility of an underlying malignancy should be considered in patients with atypical symptoms in the locomotor system, an unexpected course or anomalous secondary symptoms.

Discriminating ability of plasma viscosity and erythrocyte sedimentation rate; a prospective study at the rheumatology out-patient department.

Measurements of plasma viscosity (PV) and erythrocyte sedimentation rate (ESR) are supposed to reflect the complex of acute phase reactants in inflammations. Both tests were prospectively studied at the rheumatology out-patient department with regard to their ability to discriminate between inflammatory and non-inflammatory rheumatic diseases in new patients (n = 235). PV and ESR were measured using the Coulter Viscometer II and the Westergren method, respectively. The Receiver Operating Characteristic curve for PV was slightly better than for ESR. However, at the higher cut-off points (PV greater than 1.81 mPa.s, ESR greater than 25 mm/l hr), sensitivities, specificities, predictive values and odds ratios were more favourable for ESR. Furthermore, since the costs of PV measurement are considerably higher, there is no reason for an implementation of PV in the daily routine of the rheumatologist at the outpatient department.

Effects of a coping intervention on patients with rheumatic diseases: results of a randomized controlled trial.

OBJECTIVE: To test the effects (on coping, social interactions, loneliness, functional health status, and life satisfaction) of an intervention aimed at teaching people with rheumatic diseases to cope actively with their problems. METHODS: A total of 168 patients with chronic rheumatic disorders affecting the joints were randomly assigned to a coping intervention group, a mutual support control group, or a waiting list control group. Measurements were by self-report questionnaires. RESULTS: Post-intervention measurements showed that the coping intervention increased action-directed coping and functional health status, but these effects did not persist up to 6-months followup. In patients who attended at least half of the 10 sessions, the coping intervention contributed to decreased loneliness at post-intervention and to improvements in social interactions and life satisfaction at 6-months followup. CONCLUSION: Teaching patients with rheumatic diseases to cope actively with their problems had positive impacts. Consequently it is recommended that the coping intervention be incorporated into regular care. Maintenance sessions are advisable.

Development of a questionnaire to investigate patient compliance with antirheumatic drug therapy.

OBJECTIVE: To develop a rheumatology oriented questionnaire that measures compliance to drug regimen and identifies factors that contribute to suboptimal compliance in patients with rheumatoid arthritis (RA), polymyalgia rheumatica (PMR), and gout. METHODS: Thirty-two patients (16 RA, 8 PMR, 8 gout) participated in semistandardized home interviews about their attitude toward their antirheumatic medication, actual drug intake, and reasons for not taking medication. A focus group interview with 7 patients (3 RA, 2 PMR, 2 gout) was held. Following an advertisement in the rheumatology patient organization magazine (>8000 patients) 14 patients (9 RA, 5 PMR) telephoned and explained their reasons for noncompliance. All interviews were recorded on tape, transcribed, and independently reviewed by 2 investigators. Thirty-one statements were selected. After a field test, the phrasing of some items was revised. The questionnaire was then sent by mail to 117 consecutive outpatients (58 RA, 30 PMR, 29 gout). RESULTS: Twelve items were excluded because of low or high corrected item-total correlation or skew distribution of the answers. Internal consistency of the remaining 19 items was intermediate (0.71). Discriminant analyses with an overall patient self-report compliance measure showed a sensitivity of 98%, a specificity of 67%, and a Cohen's kappa of 0.71. Stepwise discriminant analyses revealed that 3 items classified 84% of all cases correctly with a sensitivity of 99%, specificity 80%, and kappa 0.78. CONCLUSION: The 19 item measure was well accepted. It is useful to detect possible barriers for optimal compliance and to predict patient compliance to drug regimen.

Employment, work disability, and work days lost in patients with ankylosing spondylitis: a cross sectional study of Dutch patients.

OBJECTIVE: To evaluate employment status, work disability, and work days lost in patients with ankylosing spondylitis (AS). METHODS: A questionnaire was sent to 709 patients with AS aged 16-60. The results of 658 of the patients could be analysed. RESULTS: After adjustment for age, labour force participation was decreased by 15.4% in male patients and 5.2% in female patients compared with the general Dutch population. Work disability (all causes) was 15.7% and 16.9% higher than expected in the general population for male and female patients respectively. In particular, the proportion of those with a partial work disability pension was increased. Patients with a paid job lost 5.0% of work days as the result of having AS, accounting for a mean of 10.1 days of sick leave due to AS per patient per year in addition to the national average of 12.3 unspecified days of sick leave. CONCLUSION: This study on work status in AS provides data adjusted for age and sex, and the differences from the reference population were significant. The impact of AS on employment and work disability is considerable. Work status in patients with AS needs more attention as an outcome measure in future research.

Effects of fish oil supplementation in rheumatoid arthritis.

Sixteen patients with rheumatoid arthritis entered a trial to determine the clinical and biochemical effects of dietary supplementation with fractionated fish oil fatty acids. A randomised, double blind, placebo controlled crossover design with 12 week treatment periods was used. Treatment with non-steroidal anti-inflammatory drugs and with disease modifying drugs was continued throughout the study. Placebo consisted of fractionated coconut oil. The following results favoured fish oil rather than placebo: joint swelling index and duration of early morning stiffness. Other clinical indices improved but did not reach statistical significance. During fish oil supplementation relative amounts of eicosapentaenoic acid and docosahexaenoic acid in the plasma cholesterol ester and neutrophil membrane phospholipid fractions increased, mainly at the expense of the omega-6 fatty acids. The mean neutrophil leucotriene B4 production in vitro showed a reduction after 12 weeks of fish oil supplementation. Leucotriene B5 production, which could not be detected either in the control or in the placebo period, rose to substantial quantities during fish oil treatment. This study shows that dietary fish oil supplementation is effective in suppressing clinical symptoms of rheumatoid arthritis.

Assessment of disability with the World Health Organisation Disability Assessment Schedule II in patients with ankylosing spondylitis.

OBJECTIVE: To investigate in ankylosing spondylitis (AS) whether the newly developed World Health Organisation Disability Assessment Schedule II (WHODAS II) is a useful instrument for measuring disability, to assess its responsiveness in relation to other traditional disease specific instruments, and to identify factors that are associated with both short term and long term scores on the WHODAS II. METHODS: Patients with AS from a randomised controlled trial assessing the efficacy of spa treatment (n=117) and from a five year longitudinal observational study (n=97) participated. The patients completed several questionnaires, including the WHODAS II. After a three week course of spa treatment, 31 patients again completed all questionnaires to assess responsiveness. To determine to what degree the WHODAS II reflects some AS oriented measures on disease activity, functioning, and quality of life, correlation coefficients between the WHODAS II and these other questionnaires were calculated. Responsiveness was calculated by the effect size (ES) and standardised response mean (SRM). Linear regression analysis was performed to explore which factors might be associated with short term changes on the WHODAS II and to investigate (in the observational study) which factors of WHODAS II might predict disability five years later. RESULTS: Mean score on the WHODAS II was 23.9 (SD 15.5 (range 0.0-76.1)). Scores on the WHODAS II were significantly correlated with all disease specific questionnaires measured (all p<0.001). The WHODAS II showed a comparable short term responsiveness score (SRM 0.41; ES 0.39). In regression analysis these short term changes on the WHODAS II were significantly associated with changes in functioning (beta coefficient 4.25, 95% confidence interval (95% CI) 1.24 to 7.26, p=0.007). In the observational study, disease activity (beta coefficient 0.35, 95% CI 0.17 to 0.53, p<0.000) as well as functioning (beta coefficient 0.23, 95% CI 0.09 to 0.38, p=0.002) seemed to significantly predict disability (WHODAS II) after five years. CONCLUSION: The WHODAS II is a useful instrument for measuring disability in AS in that it accurately reflects disease specific instruments and that it shows similar responsiveness scores. In AS, a short term change on the WHODAS II is associated with a change in physical function. At the group level, disease activity and physical functioning may predict disability after five years.

A comparative study of the usefulness of the Bath Ankylosing Spondylitis Functional Index and the Dougados Functional Index in the assessment of ankylosing spondylitis.

To determine whether the Bath Ankylosing Spondylitis Functional Index (BASFI, score 0-10) or Dougados Functional Index (DFI, score 0-40) is superior in measuring physical function in ankylosing spondylitis (AS) we studied 191 consecutive outpatients with AS in the Netherlands, France, and Belgium. The participating centers are secondary and tertiary referral centers. The external criterion for disease activity (DA) was: both patient and physician assessment of disease activity on a visual analog scale (VAS) and the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI). The external criterion for damage was 2 radiological scores of the spine; BASRI-s (Bath Ankylosing Spondylitis Radiology Index-spine) and a modified SASSS (Stoke Ankylosing Spondylitis Spine Score). Median scores for BASFI and DFI were 2.5 (range 0-10) and 8.5 (range 0-35), respectively. Spearman correlation coefficient between both indexes was 0.89. The average correlation with disease activity variables was 0.42 for BASFI and 0.41 for DFI. For both BASFI and DFI the correlation with BASRI-s was 0.42 and with SASSS 0.36. When distinguishing between patients with high and low disease activity, sensitivity for both indexes was between 76 and 94%, while specificity was between 66 and 87% for all 3 DA measures. Average misclassification between BASFI, DFI and DA was 23 and 27%, respectively. Both BASFI and DFI correlate equally well with disease activity and damage.

Relative value of erythrocyte sedimentation rate and C-reactive protein in assessment of disease activity in ankylosing spondylitis.

Our aim was to determine whether C-reactive protein (CRP) or erythrocyte sedimentation rate (ESR) is more appropriate in measuring disease activity in ankylosing spondylitis (AS). We studied 191 consecutive outpatients with AS in The Netherlands, France, and Belgium. Patients were attending secondary and tertiary referral centers. The external criterion for disease activity was: physician and patient assessment of disease activity on a visual analog scale (VAS) and the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI). In each measure we defined 3 levels of disease activity: no activity, ambiguous activity, and definite disease activity. The patients with AS (modified New York criteria) were divided into 2 groups: those with spinal involvement only (n=149) and those who also had peripheral arthritis and/or inflammatory bowel disease (IBD) (n=42). For each criterion of disease activity, the patients with no activity and with definite activity were included in receiver operator curves and used to determine cutoff values with the highest sensitivity and specificity. We also calculated Spearman correlations. The median CRP and ESR were 16 mg/l and 13 mm/h, respectively, in the spinal group and 25 mg/l and 21 mm/h, respectively, in the peripheral/IBD group. In both groups the Spearman correlation coefficients between CRP and ESR were around 0.50. There was moderate to poor correlation between CRP, ESR, and the 3 disease activity variables (0.06-0.48). Sensitivity for both ESR and CRP was 100% for physician assessment and between 44 and 78% for patient assessment of disease activity and the BASDAI, while specificity was between 44 and 84% for all disease activity measures. The positive predictive values of CRP and ESR in our setting were low (0.15-0.69). We conclude that neither CRP nor ESR is superior to assess disease activity.

Is avoidant coping independent of disease status and stable over time in patients with ankylosing spondylitis?

OBJECTIVE: To determine whether avoidant coping in ankylosing spondylitis (AS) is independent of disease status and whether it is stable over time. METHODS: 658 patients with AS completed a postal questionnaire on health status, including pain and stiffness (BASDAI), physical function (BASFI), and coping (CORS). In CORS, "decreasing activities to cope with pain" and "pacing to cope with limitations" reflect avoidant behavioural coping. Ninety patients continued in a longitudinal study and 70 completed the CORS after four years. The adjusted contribution of age, sex, disease duration, educational level, pain (BASDAI), and physical function (BASFI) to the two avoidant coping strategies at first assessment was determined by multiple linear regression. Agreement between coping at first assessment and four years later was determined by intraclass correlation, and the correlation between change in coping and change in disease status over time by Pearson's correlation. RESULTS: At first assessment, worse physical function (BASFI) and more pain (BASDAI) were associated with "decreasing activities to cope with pain". Worse physical function, but not pain, was associated with "pacing to cope with limitations". The contribution of physical function or pain to the total explained variance in each of the coping strategies was small. Disease duration was not a determinant of avoidant coping, but greater age was associated with "pacing to cope with limitations". Change in avoidant coping strategies over time could not be explained by change in function or pain. CONCLUSIONS: In AS, avoidant coping at a particular time is largely independent of disease duration or status. Variability in avoidant coping over a limited period of four years cannot be explained by change in disease status.

Withdrawal from labour force due to work disability in patients with ankylosing spondylitis.

OBJECTIVE: To investigate withdrawal from the labour force because of inability to work owing to ankylosing spondylitis (AS) and to determine the characteristics of patients with no job because of work disability attributable to AS. METHODS: A postal questionnaire was sent to 709 patients with AS aged 16-60 years followed up by a rheumatologist. Kaplan-Meier survival statistics were used to assess the time lapse between diagnosis and withdrawal from work. Standardised incidence ratios were calculated to compare withdrawal from the labour force in patients with AS and the general population. Determinants of withdrawal were assessed by Cox's proportional hazard regression analysis using variables assumed to be time independent. Cross sectional characteristics of patients without a job owing to disability were further analysed by simple and multiple regression analyses. RESULTS: A total of 658 patients returned the questionnaire. Of 529 patients with a paid job before diagnosis of AS, 5% had left the labour force within the first year after the diagnosis, 13% after 5 years, 21% after 10 years, 23% after 15 years, and 31% after 20 years. Age and sex adjusted risk for withdrawal was 3.1 (95% CI 2.5 to 3.7) times higher than in the general population. In patients with AS, determinants of withdrawal from work were older age at diagnosis, manual work, and coping strategies characterised by limiting or adapting activities. Patients with work disability at the time of the study were older, came from a lower social class, and were more likely to have total hip replacement, peripheral arthritis, or comorbidity. Moreover, they reported worse physical function (BAS-FI), experienced lower quality of life, and more often had extraspinal disease than those with a job. CONCLUSION: Withdrawal from work is 3.1 times higher in patients with AS than expected in the general population. Within patients, higher age at diagnosis, manual work, and unfavourable coping strategies are important determinants of withdrawal. Patients without a job experience a lower quality of life.

Work status and productivity costs due to ankylosing spondylitis: comparison of three European countries.

OBJECTIVE: To compare work disability, sick leave, and productivity costs due to ankylosing spondylitis (AS) of three European countries. METHODS: 216 patients with AS from the Netherlands, France, and Belgium participated in a two year observational study. Employment and work disability rates at baseline were adjusted for age and sex. Productivity costs were calculated by both the friction cost method and the human capital approach. The adjusted contributions of country to employment, work disability, and having an episode of sick leave were assessed by logistic regression and the contribution of the country to days of sick leave and costs by Cox proportional hazard analysis. RESULTS: 209 patients completed the two years' follow up with sufficient data for cost analysis. Adjusted employment was 55% in the Netherlands as compared with 72% in both other countries and only in the Netherlands was it lower than expected in the general population. Adjusted work disability was 41%, 23%, and 9% in the Netherlands, France, and Belgium and in all countries was higher than expected in the general population. In those with a paid job, the mean number of days of sick leave per patient per year because of AS was 19 (range 0-130), six (range 0-77), and nine (range 0-60 ) in the Netherlands, France, and Belgium respectively. Applying the friction cost method to those with a paid job resulted in mean costs per patient per year of 1257 euros (range 0-7356), 428 euros (range 0-5979), and 476 euros (range 0-2354) in the Netherlands, France, and Belgium. Applying the human capital approach to the whole group resulted in mean costs per patient per year of 8862 euros (range 0-46 818), 3188 euros (range 0-43 550), and 3609 euros (range 0-34 320) in the three countries, respectively. After adjusting for sociodemographic and disease characteristics, living in the Netherlands, as compared with both other countries, was associated with a higher chance of being work disabled (odds ratio (OR)=3.82; 95% confidence interval (CI) 1.33 to 11.01), but not with the risk of having an episode of sick leave. Similarly, living in the Netherlands contributed independently to the number of days sick leave (OR=0.65; 95% CI 0.43 to 0.97), a higher amount of friction costs (OR=0.63; 95% CI 0.42 to 0.96), and a higher amount of human capital costs (OR=0.46; 95% CI 0.32 to 0.68). CONCLUSION: There are remarkable differences in work status and productivity costs between the three European countries. This has implications for the generalisability of health economic studies.

Direct costs of ankylosing spondylitis and its determinants: an analysis among three European countries.

OBJECTIVE: To assess direct costs associated with ankylosing spondylitis (AS). To determine which variables, including country, predict costs. METHODS: 216 patients with AS from the Netherlands, France, and Belgium participated in a two year observational study and filled in bimonthly economic questionnaires. Disease related healthcare resource use was measured and direct costs were calculated from a societal perspective (true cost estimates) and from a financial perspective (country-specific tariffs). Predictors of costs were assessed using Cox's regression analysis. RESULTS: 209 patients provided sufficient data for cost analysis. Mean annual societal direct costs for each patient were euro;2640, of which 82% were direct healthcare costs. In univariate analysis costs were higher in the Netherlands than in Belgium, but this difference disappeared after adjusting for baseline differences in patients' characteristics among countries. Longer disease duration, lower education, worse physical function, and higher disease activity were predictors of costs. Mean annual direct costs from a financial perspective were euro;2122, euro;1402, and euro;941 per patient in the Netherlands, France, and Belgium, respectively. For each country, costs from a financial perspective were significantly lower than costs from a societal perspective. CONCLUSION: Direct costs for AS are substantial in three European countries but not significantly different after adjusting for baseline characteristics among countries. Worse physical function and higher disease activity are important determinants of costs, suggesting better disease control might reduce the costs of AS. The difference in costs from a societal and financial perspective emphasises the importance of an economic analysis.

Costs of ankylosing spondylitis in three European countries: the patient's perspective.

OBJECTIVE: To assess a patient's out of pocket costs, income loss, time consumption, and quality of life (QoL) due to ankylosing spondylitis (AS) in three European countries and to assess variables predicting these outcomes. METHODS: 216 patients with AS from the Netherlands, France, and Belgium participated in a two year study. Health resource use, days absent from work, time lost, and quality of life (EuroQol) were assessed by bimonthly questionnaires. AS related healthcare and non-healthcare expenditure and income loss were calculated taking into account country-specific regulations. Predictors of costs, time consumption, and QoL were analysed by Cox's regression. RESULTS: 209 patients provided data for cost analysis. Average annual healthcare and non-healthcare expenditure was euro;431 per patient and average annual income loss was euro;1371 per patient. Healthcare costs were highest for Belgian and lowest for French patients, while non-healthcare costs were highest for Dutch patients. A patient's total costs were associated with higher age and worse physical function. On average, patients with AS needed 75 minutes additional time a day because of AS. Worse physical function and higher disease activity predicted time consumption. After adjusting for baseline confounders, QoL was worse in Belgian and French than in Dutch patients. Peripheral arthritis, worse physical function, higher disease activity, and loss of income contributed to worse QoL. CONCLUSION: AS is time consuming and associated with substantial out of pocket costs. Belgian patients incur the highest healthcare payments. Poor physical function increases patient's costs and time consumption. Loss of income is associated with lower QoL.

Radiological scoring methods in ankylosing spondylitis: reliability and sensitivity to change over one year.

Our aim was to compare reliability and sensitivity to change of different radiological scoring methods in ankylosing spondylitis (AS). Two trained observers scored 30 AS radiographs twice with an interval of 4 weeks. The same two observers scored 187 AS radiographs in pairs, at baseline and after one year followup, to measure change and agreement on change. The sacroiliac (SI) joints were scored in 5 grades by the New York method and the SASSS (Stoke Ankylosing Spondylitis Spine Score). Hips were graded 0-5 (according to Larsen). Cervical and lumbar spine were graded (0-4, Bath Ankylosing Spondylitis Radiological Index, BASRI), and scored in detail (0-72, SASSS). SASSS of the cervical and lumbar spine scored on the anterior sites of the vertebrae proved most reliable, with both intra and interobserver intraclass correlation coefficients (ICC) between 0.87 and 0.97. BASRI was only moderately reliable, with Cohen's kappa ranging between 0.50 and 0.82 for intra, and 0.38-0.64 for interobserver reliability. Similarly, SI joint scores (New York, SASSS) showed intraobserver kappa between 0.56 and 0.84, and interobserver reliability with kappa between 0.37 and 0.47. Larsen hip scores proved unreliable: moderate intraobserver kappa of 0.47-0.58 and low interobserver kappa of 0.29. After retraining, interobserver kappa did not improve (0.45 and 0.17). In retrospect, a one year period was too short to measure sensitivity to change. Observers agreed that no change occurred in up to 89% of cases. A measurable change of deterioration or improvement occurred rarely. We conclude that in AS, only the SASSS method for the spine and the BASRI reached good reliability. Other methods for spine, SI joints, and hips were moderately reliable at best. There was moderate to good agreement on no change between the observers. No method showed change over a period of one year in a considerable number of patients.

Rhemulatologists' performance in dailiy practice.

OBJECTIVE: To assess rheumatologists' performance for 8 rheumatologic conditions and to explore possible explanatory factors. METHODS: After written informed consent was obtained, 27 rheumatologists (21% of all Dutch rheumatologists) practicing in 16 outpatient departments were each visited by 8 incognito "standardized patients" (SPs). The diagnoses of these 8 cases account for about 23% of all new referred patients in the Netherlands. Results for ordered lab tests as well as real radiographs with corresponding results from a radiologist were simulated. Information from the visits was obtained from the SPs, who completed predefined case-specific checklists, and by collecting data on resource utilization. Feedback was provided. RESULTS: Altogether 254 encounters took place, of which 201 were first visits and 53 were followup visits. SPs were unmasked twice during a visit. There was considerable variation in resource utilization (lab tests and imaging) between cases and between rheumatologists. Mean costs per rheumatologist ranged from US $ 4.67 to $ 65.36 per visit for lab tests and from US $ 33.15 to $ 226.84 per visit for imaging tests. No significant correlations were seen between resource utilization costs and number of years of clinical experience or performance on checklist scores. Rheumatologists with longer experience had lower total item checklist scores (r = -0.47; P < 0.05). CONCLUSION: A considerable variation in resource utilization was found among 27 Dutch rheumatologists. The information obtained is an excellent source for discussion on the appropriateness of care.