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ID PMID Title PublicationDate abstract
11596833 A review of the direct costs of rheumatoid arthritis: managed care versus fee-for-service 2001 Rheumatoid arthritis (RA) is a prevalent condition associated with pain, joint destruction and morbidity. Direct healthcare costs are 2 to 3 times higher than average costs for individuals of similar age and gender. Furthermore, utilisation and costs rise with age and disease duration. Managed care has become an increasingly popular way to organise and finance the delivery of healthcare. Studies comparing the quality of care in health maintenance organisations and fee-for-service settings have found few differences in outcomes, although reduced costs have been attributed to lower hospitalisation rates in patients with RA. We reviewed 10 studies of the direct costs of RA. In 1996 dollars, direct costs ranged from $US 2,299 per person per year in Canada to $US 13,549 in a US study focusing on patients who have been hospitalised only. Surprisingly, the contributions to direct costs--hospital care, medications and physician visits--remained relatively stable over time and the setting of care. Hospitalisation costs were the highest component of direct costs accounting, generally, for 60% or more of costs while only approximately 10% of patients with RA were hospitalised. The only exception was a managed care setting where hospitalisation costs were 16% of total direct costs. In managed care settings, costs of medications were proportionately higher than in fee-for-service settings. We conclude that in studies of the direct costs of RA the components of costs have remained relatively stable over time. This may change with the development and growing use of new RA medications including cyclo-oxygenase 2 inhibitors, interleukins, cytokines, treatments that inhibit tumour necrosis factor, and combination therapies. The effectiveness of managed care in controlling direct costs needs to be evaluated in more targeted studies.
11156544 Relative serum amyloid A (SAA) values: the influence of SAA1 genotypes and corticosteroid 2001 Feb OBJECTIVES: (1) To determine whether serum concentration of serum amyloid A (SAA) protein is influenced by the SAA1 allele in Japanese patients with rheumatoid arthritis (RA) as previously shown in a healthy control group; and (2) to analyse what factors, based on such an allelic bias, influence the relative SAA values of those patients. METHODS: SAA and C reactive protein (CRP) concentrations together with SAA1 genotypes were determined in 316 Japanese patients with RA. The relative SAA values were evaluated as an SAA/CRP ratio. RESULTS: Comparison of the three SAA1 homozygote groups showed that the SAA/CRP ratio was highest in the 1.5/1.5 group (mean 9.0, p<0.01 v the other two homozygote groups) followed by the 1.3/1.3 group (mean 7.2, NS v the 1.1/1.1 group) and the 1.1/1.1 group (mean 4.0). The SAA/CRP ratio was significantly higher in patients receiving corticosteroids regardless of the presence of allele 1.5. No clear differences in the ratio between patients with or without amyloidosis were found. CONCLUSION: The SAA1.5 allele and corticosteroid treatment had a positive influence on SAA concentrations in serum. These findings are important when evaluating SAA concentration in inflammatory diseases and when considering the cause or treatment of amyloidosis.
11028844 Intensive treatment of rheumatoid arthritis reduces need for dialysis due to secondary amy 2000 We have analysed changes in the intensity of treatment of patients with rheumatoid arthritis (RA) and its influence on the number of patients with RA and secondary amyloidosis (SA) admitted to dialysis due to end-stage renal disease. The number of visits and patients at the rheumatological outpatient clinic because of RA, the type of medication used in 1988-1997, and the number of patients with RA and SA on dialysis from 1989 to 1999 were extracted from the data set of Kuopio University Hospital. The intensity of treatment could be evaluated as the treated number of patients with RA and the number of visits at the outpatient clinic. Both the numbers increased from 1988 to 1996, patients under treatment from 201 to 550 and visits from 1091 to 2198, respectively. In 1997, the number of patients still increased (n=637), although the number of visits started to decline (n=2054), partly due to better collaboration of health centres. A marked shift from use of only symptomatic treatment or one disease-modifying antirheumatic drug (DMARD) to more common use of immunosuppressants and/or combinations of at least two DMARDs occurred in the five years from 1992 to 1997. In 1988, the figures for only nonsteroidal anti-inflammatory drugs or only glucocorticoids or one immunosuppressive drug were 24%, 8%, and 9%, and in 1997, 4%, 3%, and 22%, respectively. In 1997, 43% of the patients were treated with combinations of two or more DMARDs. The number of patients with RA on dialysis treatment and the number of new admissions each year due to SA decreased from 11 to 2 and from 5 to none, respectively. At the beginning of year 2000 there was only one patient with RA and SA on dialysis.
11224655 Polyunsaturated fatty acids and rheumatoid arthritis. 2001 Mar Rheumatoid arthritis is characterized by infiltration of T lymphocytes, macrophages and plasma cells into the synovium, and the initiation of a chronic inflammatory state that involves overproduction of proinflammatory cytokines and a dysregulated T-helper-1-type response. Eicosanoids synthesized from arachidonic acid and cytokines cause progressive destruction of cartilage and bone. The n-6 polyunsaturated fatty acid gamma-linolenic acid is the precursor of di-homo-gamma-linolenic acid. The latter and the n-3 polyunsaturated fatty acid eicosapentaenoic acid, which is found in fish oil, are able to decrease the production of arachidonic acid-derived eicosanoids and to decrease the production of proinflammatory cytokines and reactive oxygen species, and the reactivity of lymphocytes. A number of double-blind, placebo-controlled trials of gamma-linolenic acid and fish oil in rheumatoid arthritis have shown significant improvements in a variety of clinical outcomes. These fatty acids should be included as part of the normal therapeutic approach to rheumatoid arthritis. However, it is unclear what the optimal dosage of the fatty acids is, or whether there would be extra benefit from using them in combination.
10529126 Compliance to drug treatment of patients with rheumatoid arthritis: a 3 year longitudinal 1999 Oct OBJECTIVE: Patient compliance is considered necessary for the success of drug treatment in chronic diseases. We document compliance with drug treatment and the factors affecting it in a cohort of patients with rheumatoid arthritis (RA). METHODS: A prospective cohort study of 556 patients with RA followed for 3 years in 4 counties: Oslo, Norway; Groningen, The Netherlands; and Nancy and Reims, France. Compliance to treatment was assessed annually by interview in terms of adherence to the dose and timing of the prescribed drug regimen. RESULTS: Of the 556 subjects, 429 (77.2%) were taking medication for RA throughout the observation period. Consistent behavior was recorded in 59.5% of cases: 35.7% were consistently compliant, and 23.8% consistently noncompliant. Factors significantly associated with good compliance were older age (p = 0.00), female sex (p = 0.03), decreased disability (p = 0.04), very satisfactory contacts with health care professionals (p = 0.03), and more personal knowledge about the disease and its treatment (p = 0.03). CONCLUSION: This longitudinal study identified compliance behavior as consistent over time in 60% of patients, determined by quality of contact with professionals and the amount of patient information available.
9117178 Faecal microbial flora and disease activity in rheumatoid arthritis during a vegan diet. 1997 Jan To clarify the role of the faecal flora in the diet-induced decrease of rheumatoid arthritis (RA) activity, 43 RA patients were randomized into two groups: the test group to receive living food, a form of uncooked vegan diet rich in lactobacilli, and the control group to continue their ordinary omnivorous diets. Based on clinical assessments before, during and after the intervention period, a disease improvement index was constructed for each patient. According to the index, patients were assigned either to a group with a high improvement index (HI) or to a group with a low improvement index (LO). Stool samples collected from each patient before the intervention and at 1 month were analysed by direct stool sample gas-liquid chromatography of bacterial cellular fatty acids. This method has proved to be a simple and sensitive way to detect changes and differences in the faecal microbial flora between individual stool samples or groups of them. A significant, diet-induced change in the faecal flora (P = 0.001) was observed in the test group, but not in the control group. Further, in the test group, a significant (P = 0.001) difference was detected between the HI and LO categories at 1 month, but not in the pre-test samples. We conclude that a vegan diet changes the faecal microbial flora in RA patients, and changes in the faecal flora are associated with improvement in RA activity.
9308519 Silastic metacarpophalangeal joint arthroplasty in patients with rheumatoid arthritis. 1997 Sep Two hundred sixty-four patients with rheumatoid arthritis were treated with 901 Swanson silastic arthroplasties of the metacarpophalangeal joints. Average followup was 8 years with a minimum of 2 years. Preoperative ulnar deviation averaged 45 degrees and improved to an average of 15 degrees postoperatively. Active flexion arc averaged 40 degrees preoperatively and 50 degrees postoperatively, an increase of 10 degrees. The extensor lag postoperatively improved to 10 degrees from 50 degrees preoperatively, placing the arc of metacarpophalangeal joint motion between 10 degrees and 60 degrees flexion. Complications included dehiscence and delayed wound healing (2%), superficial infection (0.5%), deep infection (3%), and prosthetic fracture (14%). Subjectively, most patients thought that their postoperative function was improved. This was thought to be attributable in part to the correction of the ulnar deviation deformity of the fingers, and the shifting of the arc of motion of the metacarpophalangeal joints to one allowing increased metacarpophalangeal extension, thereby improving the opening capacity of the digits and the overall function of the hand.
9567626 [Diffuse interstitial pneumopathy after the treatment with gold salts of a patient with rh 1997 Apr We present the case of a male patient with sero-negative rheumatoid arthritis, treated with gold salts, admitted for clinical symptoms and chest X-ray alterations suggesting an interstitial lung disease. This was confirmed by complex lung function tests and fiber bronchoscopy with broncho-alveolar lavage. Considerations are made about the etiology of interstitial lung disease (pulmonary determination of the rheumatoid arthritis or secondary to the gold salts therapy), about the treatment and long-term prognosis, and about the good clinical, functional and radiological evolution under treatment.
9184263 Rheumatoid arthritis: a commonly misused diagnosis by the general population. 1997 May The purpose of this study was to explore what a young general population include when they answer questions concerning the diagnosis rheumatoid arthritis (RA). Altogether 14,420 subjects answered questionnaires concerning disease history, living habits and musculoskeletal pain. They were also asked specifically if they, or any close relative, had RA. One hundred and sixteen (1.6%) men and 115 (1.6%) women reported that they had the disease. Altogether 14 (12%) men and 23 (20%) women of those answering "yes" to the RA question, were found to have the disease verified according to their hospital records. Fifty-five (25%) of the subjects who reported to have RA, were classified in their hospital records as having other defined rheumatic diseases. Our study indicates that when the general population refers to the diagnosis of RA, they include most defined rheumatic diseases as well as unspecified arthralgia. We find it interesting that such a substantial number of young people report they have this serious disease. We therefore recommend that other measures should be used or used in addition to mailed questionnaires when exploring the prevalence of RA.
9770764 Matrix metalloproteinases 2 and 9 in canine rheumatoid arthritis. 1998 Aug 22 Matrix metalloproteinases (MMPs) are considered important mediators of tissue damage in joint diseases. The levels of MMPs 2 and 9 were measured in samples of synovial fluid from 20 joints in seven dogs with rheumatoid arthritis by gelatin zymography. The results were compared with the actual gelatinolytic activity of the fluid measured in a gelatin-degradation ELISA. The gelatinolytic activity in synovial fluid from arthritic joints was markedly greater than that in fluid from disease-free joints. The zymographic activity attributable to MMP-9 (identified by Western blotting) was absent from synovial fluid from control joints but prominent in fluid from arthritic joints, and in these joints the presence of a 75 kDa form of MMP-9 was correlated with the gelatinolytic activity of the fluid measured by the ELISA (r = 0.81, P < 0.05). Synovial fluid from one dog with rheumatoid arthritis was examined before and after treatment with corticosteroids. After treatment its zymographic pattern had returned to normal.
11003387 Genetic dissection of collagen-induced arthritis in Chromosome 10 quantitative trait locus 2000 Sep Rat Chromosome 10 (RNO10) harbors Cia5, a non-MHC quantitative trait locus (QTL) that regulates the severity of type II collagen-induced arthritis (CIA) in DAxF344 and DAxBN F2 rats. CIA is an animal model with many features that resemble rheumatoid arthritis. To facilitate analysis of Cia5 independently of the other CIA regulatory loci on other chromosomes, DA recombinant QTL speed congenic rats, DA.F344(Cia5), were generated. These QTL congenic rats have a large chromosomal segment containing Cia5 (interval size < or =80.1 cM) from CIA-resistant F344 rats introgressed into their genome. Phenotypic analyses of these rats for susceptibility and severity of CIA confirmed that Cia5 is an important disease-modifying locus. CIA severity was significantly lower in the Cia5 congenic rats than in DA controls. We also generated DA Cia5 speed sub-congenic rats, DA.F344(Cia5a), which had a smaller segment of the F344 genome, Cia5a, comprising only the distal q-telomeric end (interval size < or = 22.5 cM) of Cia5, introgressed into their genome. DA.F344(Cia5a) sub-congenic rats also exhibited reduced CIA disease severity compared with the parental DA rats. The regulatory effects in both congenic strains were sex influenced. The disease-ameliorating effect of the larger fragment, Cia5, was greater in males than in females, but the effect of the smaller fragment, Cia5a, was greater in females. We also present an improved genetic linkage map covering the Cia5/Cia5a region, which we have integrated with two rat radiation hybrid maps. Comparative homology analysis of this genomic region with mouse and human chromosomes was also undertaken. Regulatory loci for multiple autoimmune/inflammatory diseases in rats (RNO10), mice (MMU11), and humans (HSA17 and HSA5q23-q31) map to chromosomal segments homologous to Cia5 and Cia5a.
10917993 Management of leg ulcers in patients with rheumatoid arthritis or systemic sclerosis: the 2000 Aug PURPOSE: We assessed the etiology and the prevalence of peripheral arterial and venous disease in leg ulcers in patients with rheumatoid arthritis and systemic sclerosis and analyzed the outcome after treatment of macrovascular disease. METHODS: A clinical study on 15 consecutive patients with chronic leg ulcers in collagen vascular disease (nine patients with rheumatoid arthritis, six patients with systemic sclerosis) was carried out in a referral center. Angiography was used when the ankle-arm index was less than 0.8; venography was used when venous reflux was detectable by means of a hand-held Doppler examination. Therapies included percutaneous transluminal angioplasty (seven patients), femoropopliteal bypass grafting surgery (one patient), saphenectomy of the greater saphenous vein (six patients), and split skin graft (11 patients). RESULTS: All patients with rheumatoid arthritis exhibited a multifactorial etiology of their ulcers: four of nine patients had peripheral arterial disease, and five of nine patients had venous insufficiency. In one of these patients, arterial and venous disease was combined. Five of six patients with systemic sclerosis exhibited a multifactorial etiology of their ulcers: three of six patients had peripheral arterial disease, and three of six patients had venous insufficiency. One of these patients had both arterial and venous disease. In patients with rheumatoid arthritis, healing was achieved in six of nine patients, and marked improvement occurred in two of nine patients. A below-knee amputation was necessary in one patient with rheumatoid vasculitis. In patients with systemic sclerosis, healing was achieved in three of six patients, and marked improvement occurred in the other three patients. CONCLUSION: Most leg ulcers in patients with rheumatoid arthritis and systemic sclerosis disclose a multifactorial etiology. Relevant arterial and venous disease can be found in approximately half the patients. Our study suggests that revascularization and vein surgery improve the healing of leg ulcers in patients with collagen vascular disease. A prospective trial is now required to confirm these results.
10332964 HLA-DRB1 genotype influences risk for and severity of rheumatoid arthritis. 1999 May OBJECTIVE: To examine how HLA-DRB1 genotypes influence rheumatoid arthritis (RA) risk and clinical severity. METHODS: We performed polymerase chain reaction based DRB1 and tumor necrosis factor (TNF) genotyping of 309 Caucasian RA and 283 Caucasian control subjects. For risk analyses, we grouped the DRB1 alleles encoding each specific shared epitope: *0401 alone, *0404 with *0102, *0405 with *0408 and *0101, and *1001 alone. For estimates of RA outcome, we retrospectively obtained data regarding ARA classification criteria, age of disease onset and disease duration, number of slow acting antirheumatic drugs (SAARD) used, and rheumatoid factor (RF). RESULTS: Homozygous shared-epitope DRB1 genotypes, compound heterozygous genotypes, and simple heterozygous genotypes all conferred elevated relative risk (RR) for RA (RR 4.3, 11.7, and 3.5, respectively). However, compound heterozygous genotypes conferred more risk than either simple heterozygous genotype (RR 3.3, p = 0.004) or homozygous genotype (RR 2.8, p = 0.036). There was a trend toward more compound heterozygous genotypes in the male RA group than in the female RA group (p < 0.1), and male sex was associated with higher frequency of rheumatoid nodules (56 vs 35% for female RA). RA outcome was estimated by number of SAARD used; mean SAARD used was higher in male than in female RA (p < 0.01) and higher in genotypes containing one or 2 shared epitope DRB1 alleles than in those negative for shared epitope DRB1 alleles (p < 0.05). Analyses also suggested that shared epitope DRB1 genotype significantly influenced the occurrence of seropositive RA. Seropositive RA fraction was related to either number of shared epitope alleles (0, 1, or 2) represented in the DRB1 genotype, or, alternatively, to the combination of sex with shared epitope DRB1 genotype. The presence of one or 2 shared epitope DRB alleles influenced the occurrence of high titer seropositive RA as defined by sheep cell agglutination test (p < 0.01). TNFab microsatellite markers and TNF promoter polymorphisms did not influence SAARD number, seropositive RA, or high titer seropositive RA. CONCLUSION: Not all shared epitope DRB1 genotypes conferred the same relative risk, and the male RA group tended to have more compound heterozygous genotypes and more severe RA as indicated by rheumatoid nodules and SAARD usage. DRB1 genotypes with one or 2 shared epitope DRB1 alleles influenced the RA outcome as estimated by numbers of SAARD used and RF.
11564158 Macrophage-neutrophil interaction: a paradigm for chronic inflammation revisited. 2001 Oct Macrophages have been described as 'factories' of pro-inflammatory cytokines. Several years ago the present investigators reported that binding of inactive myeloperoxidase (iMPO) to the macrophage-mannose receptor resulted in the induction of TNF and other cytokines. Also, if endothelial cells were incubated with iMPO, but not enzymatically active myeloperoxidase (MPO), upregulation of cytokine mRNA and cytokines was observed. Taken in their entirety, the data suggest a dichotomy of function for myeloperoxidase; that is, enzymatically active MPO functions primarily in cell killing through the 'cytotoxic triad' and iMPO functions as an immunoregulatory molecule through the induction of numerous cytokines. These studies underscore a previously unrecognized interaction among neutrophils, endothelial cells and macrophages, resulting in the induction of TNF and perpetuation of inflammation. The inflammation induced could be relevant in a number of diseases in which neutrophils play a prominent role. The importance of this interaction in the pathogenesis of rheumatoid arthritis is currently under investigation.
9428056 Shoulder, elbow and wrist movement impairment--predictors of disability in female patients 1997 Dec To explore and describe how shoulder, elbow and wrist movement impairment and age, disease duration, disease activity and shoulder-upper arm pain are associated with disability in rheumatoid arthritis, these variables were investigated in 63 females. Multiple linear regression analysis indicated that limitations in functional shoulder-arm movement and in active wrist motion ranges explained 30-35% of the variation among the patients' results within each of the physical disability instruments used. The Ritchie index for the upper-extremity might be a predictor of disability, explaining 6-28% of the variation within different disability questionnaires, while shoulder tendalgia explained 24% of the variation in shoulder-arm disability. Altogether, however, our predicting variables only explained 11-30% of the variation in shoulder-arm disability and 25-50% of the variation in the other disability areas studied. Thus, other factors not studied here, e.g. muscle strength and hand grip function, and e.g. psychological and social factors are probably also of importance and remain to be elucidated.
10902764 Enhanced expression and DNA binding activity of two CCAAT/enhancer-binding protein isoform 2000 Jul OBJECTIVE: To investigate the activation and expression of CCAAT/enhancer-binding proteins (C/EBP), especially C/EBPbeta and -delta, in rheumatoid synovium, and their pathogenic implications in rheumatoid arthritis (RA). METHODS: The activation of C/EBPbeta and -delta was assessed in synovial tissues from patients with RA by electrophoretic mobility shift assay (EMSA); DNA binding activity of C/EBPs was evaluated by measuring EMSA band density. The expression and distribution of C/EBPbeta and -delta in synovial tissues were examined by immunohistochemistry analysis. As a control, synovial tissues from patients with osteoarthritis (OA) were studied. RESULTS: Enhanced DNA binding activity of C/EBPbeta and -delta, 2 major members of the C/EBP family, was detected in synovial tissues from RA patients, while synovial tissues from the patients with OA showed only faint or marginal activity (mean +/- SEM arbitrary units [AU] RA 23.3 +/- 11.7 in RA versus 4.5 +/- 1.3 in OA; P < 0.05). Moreover, the binding activities of the C/EBP proteins were correlated with both serum C-reactive protein levels (r = 0.62, P < 0.05) and synovial interleukin-6 messenger RNA levels (r = 0.60, P < 0.05). In immunohistochemistry studies, C/EBPbeta and -delta were detected predominantly in the rheumatoid synovial lining cells (both CD14+ and CD14- cells). CONCLUSION: C/EBPbeta and -delta may contribute to the pathology of rheumatoid synovitis.
11340386 Postoperative inflammation after cataract surgery in patients with rheumatoid arthritis. 2001 May The purpose of the present study was to assess the influence of preoperative activity of rheumatoid arthritis (RA) on early postoperative anterior chamber inflammation after phacoemulsification and intraocular lens implantation. Twenty-three eyes in 18 patients were included in our study. On the first postoperative day, anterior chamber inflammation was observed in 11 eyes (47.8%). Five days after surgery, we found postoperative inflammation only in 1 eye (4.3%). Keratic precipitates were observed in 1 eye (4.3%) on the second postoperative day. We found no correlation between the extent of anterior chamber inflammation and the preoperative activity of RA. Postoperative anterior chamber inflammation was also not associated with the medical management of RA.
10330589 [Physical criteria of pathological processes. III. Structure of the correlation between th 1999 Jan The activity of serum complement proteins and the level of steady brain potential in patients with systemic lupus erythematosus and rheumatoid arthritis were determined. The statistical analysis indicated that there is a correlation between the parameters of the complement system and neurophysiological characteristics. The differences between rheumatoid arthritis and systemic lupus erythematosus are observed in the mean values of activity of complement proteins and the steady potential, their dispersions, and the structure of correlations between immunological and neurophysiological parameters.
9389220 Pulmonary function tests and high resolution computed tomography of the lungs in patients 1997 Oct OBJECTIVE: To compare the results of pulmonary function tests (PFTs) and high resolution computed tomography (HRCT) of the lungs in rheumatoid arthritis (RA) patients. METHODS: Sixty eight patients (54 women, 14 men) fulfilling the revised criteria for RA were consecutively included in a transversal prospective study. Their mean age was 58.8 years (range: 35-82) and the mean duration of the disease was 12 years (range: 5-16). Rheumatoid factor was positive in 52 patients (76.5%). Fifty two patients (76.5%) were lifelong non-smokers. Detailed medical and drug histories were obtained. PFTs comprised spirometry and gas transfer measurements. Results for PFTs were expressed as percentage of predicted values for each individual adjusted for age, sex, and height. HRCT was undertaken with a Siemens Somatom Plus. RESULTS: A significant decrease of FEV1/ FVC, FEF25%, FEF50%, FEF75%, FEF25-75%, and TLCO was observed (p < 0.05) and 13.2% of the patients had a small airways involvement defined by a decrease of FEF25-75% below 1.64 SD. The most frequent HRCT findings were: bronchiectasis (30.5%), pulmonary nodules (28%), and air trapping (25%). The patients with small airways involvement had a high frequency of recurrent bronchitis (75% v 34%, p = 0.05) and bronchiectasis (71% v 23%, p = 0.019). The patients with bronchiectasis were characterised by low values of FEV1, FVC, FEF25-75%, and TLCO (p < 0.01), a high prevalence of small airways involvement (29% v 5%, p = 0.019), and a low prevalence of HLA DQA1 *0501 allele (14% v 33%, p < 0.05). CONCLUSION: This study suggests a significant association between small airways involvement on PFTs and bronchiectasis on HRCT in unselected RA patients.
9093799 The determination of pyridinium crosslinks in urine and serum as a possible marker of cart 1997 Mar The determination of the collagen crosslinks pyridinoline (Pyd) and deoxypyridinoline (Dpyd) seems to be a successful way of characterizing topic destructive processes in rheumatoid arthritis (RA). Dpyd is a specific marker of collagen I resorption in bone, whereas Pyd is released from types I and II collagen in bone and cartilage. Both crosslinks were examined in 38 RA patients concurrently by RP-gradient-HPLC in urine and serum. A positive correlation was found between the inflammatory activity (measured by CrP) and the level of collagen crosslinks in urine. A correlation between serum and urine concentrations was demonstrable for Pyd, but not for Dpyd. Different elimination kinetics for fragments containing either Pyd or Dpyd are a possible explanation for this observation. The ratio of Pyd/Dpyd is known to be a useful marker to distinguish between destruction of cartilage and bone collagen. Because the Pyd/Dpyd ratio in urine does not necessarily correspond to that in serum, probably as a result of metabolic or elimination processes, the usefulness of the relationship between the crosslinks in urine as a method of differentiating between cartilage and bone degradation must be questioned.