Pharmacokinetic-pharmacodynamic modelling and simulation of methotrexate dosing in patients with rheumatoid arthritis.

AIMS: To develop a non-linear mixed-effects population pharmacokinetic and pharmacodynamic (PK-PD) model describing the change in the concentration of methotrexate polyglutamates in erythrocytes (ery-MTX-PGn with "n" number of glutamate, representing PK component) and how this relates to modified 28-joint Disease Activity Score incorporating erythrocyte sedimentation rate (DAS-28-3) for rheumatoid arthritis (RA), representing PD component. METHODS: An existing PK model was fitted to data from a study consisting of 117 RA patients. The estimation of population PK-PD parameters was performed using stochastic approximation expectation maximisation algorithm in Monolix 2021R2. The model was used to perform Monte Carlo simulations of a loading dose regimen (50mg subcutaneous methotrexate as loading doses, then 20mg weekly oral methotrexate) compared to a standard dosing regimen (10mg weekly oral methotrexate for 2 weeks, then 20mg weekly oral methotrexate). RESULTS: Every 40 nmol/L increase in ery-MTX-PG3-5 total concentration correlated with 1-unit reduction in DAS-28-3. Significant covariate effects on the therapeutic response of methotrexate included the use of prednisolone in the first 4 weeks (positive use correlated with 25% reduction in DAS-28-3 when other variables were constant) and patient age (every 10-year increase in age correlated with 3.4% increase in DAS-28-3 when other variables were constant). 4 methotrexate loading doses led to a higher percentage of patients achieving a good/moderate response compared to the standard regimen (Week 4: 87.6% vs. 39.8%; Week 10: 64.7% vs. 57.0%). CONCLUSIONS: A loading dose regimen was more likely to achieve higher ery-MTX-PG concentration and better therapeutic response after 4 weeks of methotrexate treatment.

Female reproductive status and exogenous sex hormone use in rheumatoid arthritis patients treated with tocilizumab and csDMARDs.

OBJECTIVES: Sex is well known to influence risk, severity and treatment outcomes of RA, although the underlying causes are uncertain. The aim of this research was to examine whether factors influencing female sex hormones (reproductive status and exogenous sex hormone use) are associated with the efficacy of DMARDs. METHODS: Individual participant data were pooled from five phase 3 clinical trials where RA patients were treated with tocilizumab and/or conventional synthetic DMARDs. The primary outcome was the time to first remission according to the Simplified Disease Activity Index. The relationship between menopausal status or use of exogenous sex hormones and the time of first remission was assessed via Cox proportional analysis. Analysed data included sex, baseline menopausal status (premenopausal, perimenopausal, early postmenopausal and postmenopausal), participant age, body mass index, race, number of previous DMARDs and baseline disease activity. RESULTS: Analysis included 4474 female patients, of whom 2817 (62.9%) were postmenopausal, 202 (4.5%) were early postmenopausal, 1021 (22.8%) were premenopausal and 414 (9.2%) were perimenopausal. Of these, 221 (7.8%), 13 (6.4%), 255 (25%) and 47 (11.4%), respectively, were taking exogenous sex hormones. In the pooled analysis, perimenopausal status was associated with reduced remission compared with premenopausal status [adjusted HR 0.78 (95% CI 0.61, 0.99)]. Sex hormone use was associated with significantly higher remission [adjusted HR 1.20 (95% CI 1.01, 1.43)]. CONCLUSION: Perimenopausal women were less likely to achieve remission compared with premenopausal RA patients. The use of exogenous sex hormones appeared to be associated with more frequent remission in female RA patients, particularly those who were perimenopausal and early postmenopausal, although further research is required to confirm and identify the drivers for this observation and how it interacts with menopausal status.

Mortality estimates and excess mortality in rheumatoid arthritis.

OBJECTIVES: To determine long-term (20 year) survival in RA patients enrolled in the Australian Rheumatology Association Database (ARAD). METHODS: ARAD patients with RA and data linkage consent who were diagnosed from 1995 onwards were included. Death data were obtained through linkage to the Australian National Death Index. Results were compared with age-, gender- and calendar year-matched Australian population mortality rates. Analysis included both the standardized mortality ratio (SMR) and relative survival models. Restricted mean survival time (RMST) at 20 years was calculated as a measure of life lost. Cause-specific SMRs (CS-SMRs) were estimated for International Classification of Diseases, Tenth Revision cause of death classifications. RESULTS: A total of 1895 RA patients were included; 74% were female, baseline median age 50 years (interquartile range 41-58), with 204 deaths. There was no increase in mortality over the first 10 years of follow up, but at 20 years the SMR was 1.49 (95% CI 1.30, 1.71) and the relative survival was 94% (95% CI 91, 97). The difference between observed (18.41 years) and expected (18.68 years) RMST was 4 months. Respiratory conditions were an important underlying cause of death in RA, primarily attributable to pneumonia [CS-SMR 5.2 (95% CI 2.3, 10.3)] and interstitial lung disease [CS-SMR 7.6 (95% CI 3.0, 14.7)], however, coronary heart disease [CS-SMR 0.82 (95% CI 0.42, 1.4)] and neoplasms [CS-SMR 1.2 (95% CI 0.89, 1.5)] were not. CONCLUSION: Mortality risk in this RA cohort accrues over time and is moderately increased at 20 years of follow-up. Respiratory diseases may have supplanted cardiovascular diseases as a major contributor to this mortality gap.

Quantitation of methotrexate polyglutamates in human whole blood, erythrocytes and leukocytes collected via venepuncture and volumetric absorptive micro-sampling: a green LC-MS/MS-based method.

Low-dose methotrexate (MTX) plays a key role in treatment of rheumatoid arthritis. However, not all patients respond satisfactorily, and no therapeutic drug monitoring has been implemented in clinical practice, despite the fact that MTX therapy has now been available for decades. Analysis of individual intracellular MTX metabolites among rheumatoid arthritis (RA) patients is hampered by the low intracellular concentrations of MTX-PGs which require a highly sensitive method to quantify. Here, we present a rapid and highly sensitive LC (HILIC) MS/MS method with LLOQ 0.1 nM, 0.8 nmol/L for each metabolite of MTX-PG1-5 and MTX-PG6-7 respectively. Over a linear range of 0.1-100 nM, 0.8-100 nmol/L for each metabolite of MTX-PG1-5 and MTX-PG6-7, respectively, the inter- and intra- accuracy and precision were within 15% of the nominal value for all MTX metabolites. The presented assay was used to assess and compare MTX metabolite concentrations extracted from four different matrices: red blood cells, plasma, peripheral blood mononuclear cells, and whole blood that have been collected either using traditional venepuncture or volumetric absorptive micro-sampling (VAMS) sampling techniques. The presented method not only improves analyte coverage and sensitivity as compared to other published methods; it also improves the greenness.

Comprehensive analysis of the major histocompatibility complex in systemic sclerosis identifies differential HLA associations by clinical and serological subtypes.

OBJECTIVE: The greatest genetic effect reported for systemic sclerosis (SSc) lies in the major histocompatibility complex (MHC) locus. Leveraging the largest SSc genome-wide association study, we aimed to fine-map this region to identify novel human leucocyte antigen (HLA) genetic variants associated with SSc susceptibility and its main clinical and serological subtypes. METHODS: 9095 patients with SSc and 17 584 controls genome-wide genotyped were used to impute and test single-nucleotide polymorphisms (SNPs) across the MHC, classical HLA alleles and their composite amino acid residues. Additionally, patients were stratified according to their clinical and serological status, namely, limited cutaneous systemic sclerosis (lcSSc), diffuse cutaneous systemic sclerosis (dcSSc), anticentromere (ACA), antitopoisomerase (ATA) and anti-RNApolIII autoantibodies (ARA). RESULTS: Sequential conditional analyses showed nine SNPs, nine classical alleles and seven amino acids that modelled the observed associations with SSc. This confirmed previously reported associations with HLA-DRB1*11:04 and HLA-DPB1*13:01, and revealed a novel association of HLA-B*08:01. Stratified analyses showed specific associations of HLA-DQA1*02:01 with lcSSc, and an exclusive association of HLA-DQA1*05:01 with dcSSc. Similarly, private associations were detected in HLA-DRB1*08:01 and confirmed the previously reported association of HLA-DRB1*07:01 with ACA-positive patients, as opposed to the HLA-DPA1*02:01 and HLA-DQB1*03:01 alleles associated with ATA presentation. CONCLUSIONS: This study confirms the contribution of HLA class II and reveals a novel association of HLA class I with SSc, suggesting novel pathways of disease pathogenesis. Furthermore, we describe specific HLA associations with SSc clinical and serological subtypes that could serve as biomarkers of disease severity and progression.

Repeat serological testing for anti-citrullinated peptide antibody after commencement of therapy is not helpful in patients with seronegative rheumatoid arthritis.

AIM: To Investigate the prevalence of seroconversion to ACPA after commencement of triple disease-modifying anti-rheumatic drug (DMARD) treat-to-target therapy. BACKGROUND: Anti-citrullinated peptide antibody (ACPA) and rheumatoid factor (RF) define 'seropositive' rheumatoid arthritis (RA). Both predict unfavourable disease course, development of extra-articular features and treatment outcomes. We investigated the prevalence of seroconversion to ACPA after commencement of triple disease-modifying anti-rheumatic drug (DMARD) treat-to-target therapy. METHODS: DMARD-naïve patients with RA according to the 1987 American College of Rheumatology criteria and disease duration of <96 weeks were enrolled. RF and ACPA levels were recorded at baseline and sequentially during triple DMARD therapy. RESULTS: A total of 368 patients were followed for a median of 272 weeks. Of 154 patients seronegative for ACPA at recruitment, 10 (6.5%) seroconverted at some point. Nine of these were positive for RF at baseline and baseline RF titre was predictive of seroconversion. Four (2.6%) patients remained seropositive. No patients seroconverted from negative to positive for both RF and ACPA. Median time to seroconversion for ACPA was 29 months. CONCLUSION: Persistent seroconversion of ACPA from negative to positive after diagnosis in patients with RA is uncommon. ACPA and RF double negative patients are highly unlikely to ever develop ACPA positivity with a risk <1%. It is therefore unlikely to be helpful or cost effective to perform serial ACPA measurements in patients with seronegative RA after commencement of a treat-to-target strategy.

Development and validation of the Scleroderma Clinical Trials Consortium Damage Index (SCTC-DI): a novel instrument to quantify organ damage in systemic sclerosis.

OBJECTIVE: We sought to develop the first Damage Index (DI) in systemic sclerosis (SSc). METHODS: The conceptual definition of 'damage' in SSc was determined through consensus by a working group of the Scleroderma Clinical Trials Consortium (SCTC). Systematic literature review and consultation with patient partners and non-rheumatologist experts produced a list of potential items for inclusion in the DI. These steps were used to reduce the items: (1) Expert members of the SCTC (n=331) were invited to rate the appropriateness of each item for inclusion, using a web-based survey. Items with >60% consensus were retained; (2) Using a prospectively acquired Australian cohort data set of 1568 patients, the univariable relationships between the remaining items and the endpoints of mortality and morbidity (Physical Component Summary score of the Short Form 36) were analysed, and items with p<0.10 were retained; (3) using multivariable regression analysis, coefficients were used to determine a weighted score for each item. The DI was externally validated in a Canadian cohort. RESULTS: Ninety-three (28.1%) complete survey responses were analysed; 58 of 83 items were retained. The univariable relationships with death and/or morbidity endpoints were statistically significant for 22 items, with one additional item forced into the multivariable model by experts due to clinical importance, to create a 23-item weighted SCTC DI (SCTC-DI). The SCTC-DI was predictive of morbidity and mortality in the external cohort. CONCLUSIONS: Through the combined use of consensus and data-driven methods, a 23-item SCTC-DI was developed and retrospectively validated.

CD40L-Dependent Pathway Is Active at Various Stages of Rheumatoid Arthritis Disease Progression.

The inflammatory CD40-CD40L pathway is implicated in various autoimmune diseases, but the activity status of this pathway in various stages of rheumatoid arthritis (RA) progression is unknown. In this study, we used gene signatures of CD40L stimulation derived from human immature dendritic cells and naive B cells to assess the expression of CD40-downstream genes in synovial tissues from anti-citrullinated protein Ab-positive arthralgia, undifferentiated arthritis (UA), early RA, and established RA cohorts in comparison with healthy donors. Interestingly, the expression of CD40LG and active full-length CD40 was increased in the disease tissues, whereas that of a dominant-negative CD40 isoform was decreased. Gene set variation analysis revealed that CD40L-responsive genes in immature dendritic cells and naive B cells were significantly enriched in synovial tissues from UA, early RA, and established RA patients. Additionally, CD40L-induced naive B cell genes were also significantly enriched in synovial tissues from arthralgia patients. In our efforts to characterize downstream mediators of CD40L signaling, we have identified GPR120 and KDM6B as novel components of the pathway. In conclusion, our data suggest that therapeutic CD40-CD40L blocking agents may prove efficacious not only in early and established RA, but also in inhibiting the progression of the disease from arthralgia or UA to RA.

Determinants of health-related quality of life in a multinational systemic sclerosis inception cohort.

OBJECTIVES: To evaluate health-related quality of life (HRQoL) and its determinants in a systemic sclerosis (SSc) multinational inception cohort. We performed a meta-analysis of data from individual countries, and compared the meta-analysis to individual country results by pooling data from each of the countries. METHODS: SSc patients within 2 years of disease onset were recruited from 5 countries participating in the International Systemic Sclerosis Inception Cohort (INSYNC). Data from each country's database were exported for analysis using a harmonised platform. HRQoL was assessed using the Medical Outcomes Short Form-36 (SF-36). Multivariate linear regression assessed associations between HRQoL and predictors in cohorts separately and meta-analyzed to generate pooled estimates. The analyses were repeated using individual patient data. RESULTS: Of the 637 SSc patients recruited, the majority was female (80.2%-83.3%), aged between 52.4-56.7 years with limited cutaneous disease subtype (48.6%-66.7%). HRQoL scores were lower for SSc patients than the general population (SF-36 physical component summary (PCS) score (36.4-39.6), mental component summary (MCS) score (41.0-46.4)). Determinants of SF-36 PCS by meta-analysis included increasing age (ß=-0.1, 95%CI -0.2, -0.01), diffuse cutaneous disease subtype (ß=-8.4, 95%CI -10.6, -6.3), and pulmonary arterial hypertension (ß=-10.9, 95%CI -16.6, -5.3). Increasing age (ß=0.09, 95%CI 0.0, 0.18) was the only variable associated with SF-36 MCS. Analyses using individual patient data revealed similar results to those of the meta-analysis of cohort data. CONCLUSIONS: Our study provides estimates of HRQoL in a large inception SSc cohort and provides evidence that individual patient data analysis is valid in the INSYNC dataset.

The role of inflammatory markers in assessment of disease activity in systemic sclerosis.

OBJECTIVES: The role of the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) in the assessment of disease activity in systemic sclerosis (SSc) remains controversial. We sought to evaluate the relationship between clinical features of SSc and raised inflammatory markers and to determine if changes in ESR and CRP reflect changes in other disease features over time. METHODS: One thousand, five hundred and forty-five patients enrolled in the Australian Scleroderma Cohort Study were observed over a mean 3.52±2.91 years and assessed at 6,119 study visits. Generalised estimating equations were used to determine the relationship between ESR≥20mm/hr and CRP≥5mg/L and features of disease. The associations between change in inflammatory markers and change in skin scores and respiratory function tests were analysed. RESULTS: Overall, there was a significant association between raised ESR and forced vital capacity (FVC)<80% predicted, diffusing capacity of the lung (DLCO)<80% predicted, pulmonary arterial hypertension (PAH), body mass index (BMI), proximal muscle strength, anaemia, and hypocomplementaemia (p<0.05). Raised CRP was significantly associated with modified Rodnan Skin Score>20, FVC<80%, DLCO<80%, PAH, digital ulcers, BMI, synovitis, tendon friction rub, anaemia, and hypocomplementaemia (p<0.05). A significant deterioration in respiratory function tests (RFTs) was associated with a 2-fold increase in both ESR and CRP (p<0.05). CONCLUSIONS: Raised inflammatory markers are associated with pulmonary, cutaneous and musculoskeletal manifestations of SSc. Rising inflammatory markers are correlated with declining respiratory function tests. This suggests inflammatory markers have a role in the assessment of SSc disease activity.

Intracellular CD3+ T Lymphocyte Teriflunomide Concentration Is Poorly Correlated with and Has Greater Variability Than Unbound Plasma Teriflunomide Concentration.

Leflunomide's active metabolite teriflunomide inhibits dihydro-oroate dehydrogenase, an enzyme essential to proliferation of T lymphocytes. As teriflunomide must reach the target site to have this effect, this study assessed the distribution of teriflunomide into T lymphocytes, as intracellular concentrations may be a superior response biomarker to plasma concentrations. CD3 MicroBeads (Miltenyi Biotec, Bergisch Gladbach, Germany) were used to extract CD3+ T cells from the peripheral blood of patients with rheumatoid arthritis who were taking a stable dose of leflunomide. Unbound plasma and intra-CD3+ T cell teriflunomide concentrations were quantified using liquid chromatography-mass spectrometry. Concentration (log transformed) and partition differences were assessed through paired Student t tests. Sixteen patients provided plasma steady-state teriflunomide samples, and eight provided a sample 6-12 weeks later. At time-point one, the geometric mean teriflunomide concentration (range) in CD3+ T cells was 18.12 µg/L (6.15-42.26 µg/L) compared with 69.75 µg/L (32.89-263.1 µg/L) unbound in plasma (P < 0.001). The mean partition coefficient (range) for unbound plasma teriflunomide into CD3+ T cells was 0.295 (0.092-0.632), which was significantly different from unity (P < 0.001). The median (range) change in teriflunomide concentration between the two time points was 14% (-10% to 40%) in unbound plasma and -29% (-69 to 138%) for CD3+ T cells. Because teriflunomide concentrations in CD3+ T cells were lower and displayed a higher intraindividual variability than the unbound plasma concentrations, its applicability as a therapeutic drug-monitoring marker may be limited.

Validity of the Workers Productivity and Activity Impairment Questionnaire: Specific Health Problem (WPAI:SHP) in patients with systemic sclerosis.

OBJECTIVES: To evaluate the construct validity of the Workers Productivity and Impairment Activity Index: Specific Health Problem (WPAI:SHP) in Australian systemic sclerosis (SSc) patients. METHODS: SSc patients, identified through the Australian Scleroderma Cohort Study database, completed the WPAI:SHP and a quality of life instrument (PROMIS-29) cross-sectionally. The construct validity of the WPAI:SHP was assessed by the correlations between the WPAI:SHP and a range of SSc health states. Non-parametric correlation, including Spearman's correlation (ρ), was used to test the validity of WPAI:SHP and ability to distinguish between different health states. RESULTS: A total of 476 completed questionnaires was returned, equating to a response rate of 63.7%. Among those under 65 years of age, 155 patients (55.2%) were in paid employment. Employed patients had a mean (± SD) age of 56.5 (9.8) years and were predominantly female (87.3%) with limited disease subtype (75.6%). The WPAI:SHP showed construct validity based on moderate to strong correlations with health status as assessed by a range of health outcome measures including disease activity (ρ=0.34-0.39, p=0.001), physical function (ρ=0.55-0.62, p=0.001), disease severity(ρ=0.55-0.62, p=0.001), fatigue (ρ= 0.62-0.63, p=0.001), pain (ρ=0.68-0.71, p=0.001), and breathlessness (ρ=0.39-0.46, p=0.001). Furthermore, according to the effect size, the WPAI:SHP scores have a large discriminative ability (d=1.26-1.47) for distinguishing SSc patients with different health outcomes. CONCLUSIONS: The WPAI is a valid questionnaire for assessing impairments in paid employment and social activities in SSc patients, and for measuring the relative differences between SSc patients with varying health states.

A Treat-to-Target Strategy Preserves Work Capacity in a Rheumatoid Arthritis Inception Cohort Treated With Combination Conventional DMARD Therapy.

OBJECTIVES: Quantification of work disability in patients with early rheumatoid arthritis (RA) receiving conventional DMARDs according to a treat-to-target strategy. METHODS: This is a retrospective cohort analysis of RA patients who received combination conventional DMARDs, escalated to achieve DAS28(ESR) remission and completed an annual work and arthritis questionnaire. Random effect mixed modeling was used to assess associations between average hours worked per week (HWPW), and baseline prognostic factors. HWPW were compared with matched population averages. Cox proportional hazards modeling was employed to evaluate associations between permanent loss of employment and treatment response, disease and demographic factors. RESULTS: Work data from 135 patients working at baseline and 137 working at any point followed for up to 14 years (range 1-14) were available for analysis. The mean age was 45 years, 70% were female, and 70% and 68% were seropositive for rheumatoid factor and anti-cyclic citrullinated peptide (anti-CCP), respectively. Men worked more hours than women; there was a highly significant association between working hours lost and increasing age (0.28 hours, P = 0.04) and female gender (11.92 hours, P < 0.001). HWPW were maintained over the study time comparable to the general population (loss of 0.78 vs. 0.24 HWPW). EULAR good responders at 6 months were more likely to be working at 10 years compared to those with moderate/no response. Permanent loss of employment and baseline age were strongly associated for anti-CCP positive participants (P = 0.04). CONCLUSIONS: Treat-to-target combination conventional DMARD therapy maintains work capacity, particularly in good responders, comparable to the general population. Improving treatment response in moderate/no responders early in disease may increase work retention.

Fish oil in knee osteoarthritis: a randomised clinical trial of low dose versus high dose.

OBJECTIVES: To determine whether high-dose fish oil is superior to low-dose supplementation for symptomatic and structural outcomes in knee osteoarthritis (OA). METHODS: A randomised, double-blind, multicentre trial enrolled 202 patients with knee OA and regular knee pain. They were randomised 1:1 to high-dose fish oil (4.5 g omega-3 fatty acids) 15 mL/day or (2) low-dose fish oil (blend of fish oil and sunola oil; ratio of 1:9, 0.45 g omega-3 fatty acids) 15 mL/day. The primary endpoints were Western Ontario and McMaster Universities Arthritis Index (WOMAC) pain score at 3, 6, 12 and 24 months, and change in cartilage volume at 24 months. Secondary outcomes included WOMAC function, quality of life, analgesic and non-steroidal anti-inflammatory drug use and bone marrow lesion score. RESULTS: Although there was improvement in both groups, the low-dose fish oil group had greater improvement in WOMAC pain and function scores at 2 years compared with the high-dose group, whereas between-group differences at 1 year did not reach statistical significance. There was no difference between the two groups in cartilage volume loss at 2 years. For other secondary endpoints, there was no difference between the two groups at 2 years. CONCLUSIONS: In people with symptomatic knee OA, there was no additional benefit of a high-dose fish oil compared with low-dose fish oil. The combination comparator oil appeared to have better efficacy in reducing pain at 2 years, suggesting that this requires further investigation. TRIAL REGISTRATION NUMBER: Australian New Zealand Clinical Trials Registry (ACTRN 12607000415404).

Reduced corticosteroid-binding globulin cleavage in active rheumatoid arthritis.

OBJECTIVE: Corticosteroid-binding globulin (CBG), the cortisol transport protein, is cleaved from high-affinity (haCBG) to low-affinity (laCBG) CBG at sites of inflammation releasing bioavailable, anti-inflammatory cortisol. Rheumatoid arthritis (RA) is a glucocorticoid-responsive disorder, with paradoxically normal cortisol levels despite elevated inflammatory mediators. Our objective was to determine whether CBG cleavage relates to RA disease activity. We hypothesized that impaired CBG cleavage may limit delivery of free cortisol to inflamed joints in RA. DESIGN: Prospective, cross-sectional observational study. SETTING AND PARTICIPANTS: Fifty-three patients with RA recruited from a Rheumatology outpatient clinic at a tertiary referral centre in Adelaide, Australia, and 73 healthy controls. MEASUREMENTS: Total CBG, haCBG and laCBG, total, free and salivary cortisol, inflammatory markers including interleukin-6 soluble receptor (IL-6sR) and macrophage migration inhibitory factor and clinical measures of disease activity. RESULTS: Among patients with RA, a wide range of disease activity scores was observed (DAS28: range 1·2-6·4). laCBG was lower in patients with RA (mean ± SEM); 153 ± 9, compared with healthy controls; 191 ± 8 nmol/l, P = 0·003. Levels of total and haCBG were higher in patients with more severe RA disease activity. Free and total cortisol, free cortisol:IL-6sR ratio and total cortisol:IL-6sR ratio correlated negatively with disease activity. CONCLUSIONS: These results suggest that patients with RA have reduced CBG cleavage compared to healthy controls and that cleavage is reduced further with higher RA disease activity. Hence, impaired CBG-mediated delivery of endogenous cortisol may perpetuate chronic inflammation in RA.

A model-based evaluation of single metrics for discriminating changes in rheumatoid arthritis disease activity.

AIMS: Composite indices for quantifying rheumatoid arthritis (RA) disease activity such as the 28-joint disease activity score (DAS28) are comprised of single parameters ('metrics') in various combinations. Population modelling methods were used to evaluate single metrics for their ability to reflect changes in disease activity with a view to understanding and improving composite indices. METHODS: A total of 11 single metrics of RA disease activity (tender and swollen joint counts, acute phase reactants and global health, pain and physical function assessments) were obtained from 203 patients with recent onset RA. Participants received combination disease-modifying anti-rheumatic drugs (DMARDs) according to a treat-to-target approach with a pre-defined protocol for treatment intensification. Models describing each metric's magnitude and variability of change from baseline to a single 'treated' state in the population were developed using nonmem(®) . Measures that displayed uniformly large changes between states across the population were ranked higher in terms of discriminatory capacity. RESULTS: Joint counts demonstrated a greater ability to discriminate changes in RA disease activity than others. Correlations between metrics demonstrated that erythrocyte sedimentation rate (ESR) had limited relationships with others for baseline scores and changes in RA disease activity (r generally < 0.2). However it appeared to be important in describing changes for those individuals where ESR levels were initially elevated. CONCLUSION: It appears unlikely that a single group of metrics may be suitable to capture disease activity changes across all RA patients and defining the most appropriate metric(s) for individual patients will be an important area of future research.

Genetic polymorphism of CYP1A2 but not total or free teriflunomide concentrations is associated with leflunomide cessation in rheumatoid arthritis.

AIM: Leflunomide, via its active metabolite teriflunomide, is used in rheumatoid arthritis (RA) treatment, yet approximately 20 to 40% of patients cease due to toxicity. The aim was to develop a time-to-event model describing leflunomide cessation due to toxicity within a clinical cohort and to investigate potential predictors of cessation such as total and free teriflunomide exposure and pharmacogenetic influences. METHODS: This study included individuals enrolled in the Early Arthritis inception cohort at the Royal Adelaide Hospital between 2000 and 2013 who received leflunomide. A time-to-event model in nonmem was used to describe the time until leflunomide cessation and the influence of teriflunomide exposure and pharmacogenetic variants. Random censoring of individuals was simultaneously described. The clinical relevance of significant covariates was visualized via simulation. RESULTS: Data from 105 patients were analyzed, with 34 ceasing due to toxicity. The baseline dropout hazard and baseline random censoring hazard were best described by step functions changing over discrete time intervals. No statistically significant associations with teriflunomide exposure metrics were identified. Of the screened covariates, carriers of the C allele of CYP1A2 rs762551 had a 2.29 fold increase in cessation hazard compared with non-carriers (95% CI 2.24, 2.34, P = 0.016). CONCLUSIONS: A time-to-event model described the time between leflunomide initiation and cessation due to side effects. The C allele of CYP1A2 rs762551 was linked to increased leflunomide toxicity, while no association with teriflunomide exposure was identified. Future research should continue to investigate exposure-toxicity relationships, as well as potentially toxic metabolites.

Determinants of unemployment amongst Australian systemic sclerosis patients: results from a multicentre cohort study.

OBJECTIVES: We sought to assess employment status, risk factors for unemployment and the associations of unemployment with patients' health related quality of life (HRQoL). METHODS: All patients enrolled in a systemic sclerosis (SSc) longitudinal cohort study, completed an employment questionnaire on enrolment. Clinical manifestations were defined based on presence at the time of enrolment. Summary statistics, chi-square tests, univariate and multivariable logistic regression were used to determine the associations of various risk factors with employment. RESULTS: Among 1587 SSc patients, 160 (20%) were unemployed at the time of cohort enrolment excluding retired patients. Of these, 63% had limited disease subtype. Mean (±SD) age at enrollment was 51.9 (±10.4) years; 13 years below the average retirement age in Australia. Mean (±SD) disease duration at recruitment was 11.1 (±10.9) years. Multivariable regression analysis revealed the presence of digital amputation (OR 3.9, 95%CI 1.7-9.1, p=0.002), diffuse disease subtype (OR 2.2, 95%CI 1.3-3.5, p-value=0.002), sicca symptoms (OR 2.7, 95%CI 1.6-4.4, p<0.001), a physical job (OR 1.8, 95%CI 1.1-3.1, p=0.03) and pulmonary arterial hypertension (OR 2.2, 95%CI 1.1-4.5, p=0.02) to be associated with unemployment. Unemployed patients had consistently poorer HRQoL scores in all domains (physical, emotional and mental health) of the SF-36 form than those who were employed. CONCLUSIONS: SSc is associated with substantial work disability and unemployment, which is in turn associated with poor quality of life. Raising awareness, identifying modifiable risk factors and implementing employment strategies and work place modifications are possible ways of reducing this burden.

The role of asymmetric dimethylarginine alone and in combination with N-terminal pro-B-type natriuretic peptide as a screening biomarker for systemic sclerosis-related pulmonary arterial hypertension: a case control study.

OBJECTIVES: Asymmetric dimethylarginine (ADMA) is a novel biomarker of endothelial cell dysfunction. In this proof of concept study, we sought to evaluate the role of ADMA as a screening biomarker for incident systemic sclerosis-related pulmonary arterial hypertension (SSc-PAH). METHODS: ADMA levels were measured using high performance liquid chromatography in 15 consecutive treatment-naive patients with newly-diagnosed SSc-PAH and compared with 30 SSc-controls without PAH. Logistic regression models were used to evaluate the independent association of ADMA with PAH. The optimal cut-point of ADMA for SSc-PAH screening was determined. NT-proBNP levels were previously measured in the same patients and the optimal cut-point of NT-proBNP of ≥210ng/mL was coupled with the optimal cut-point of ADMA to create a screening model that combined the two biomarkers. RESULTS: The PAH group had significantly higher mean ADMA levels than the control group (0.76±0.14 µM versus 0.59±0.07 µM; p<0.0001). ADMA levels remained significantly associated with PAH after the adjustment for specific disease characteristics, cardiovascular risk factors and other SSc-related vascular complications (all p<0.01). An ADMA level ≥0.7 µM had a sensitivity of 86.7%, specificity of 90.0% and AUC of 0.86 for diagnosing PAH. A screening model that combined an NT-proBNP ≥210ng/mL and/ or ADMA ≥0.7 ng/mL resulted in a sensitivity of 100% and specificity of 90% for the detection of SSc-PAH. CONCLUSIONS: In this small study, use of ADMA in combination with NT-proBNP produced excellent sensitivity and specificity for the non-invasive identification of SSc-PAH. The role of ADMA as a screening biomarker for SSc-PAH merits further evaluation.

Ten years of publicly funded biological disease-modifying antirheumatic drugs in Australia.

Biological disease-modifying antirheumatic drugs (bDMARDs) for rheumatoid arthritis (RA) treatment were among the first high-cost medicines to be subsidised in Australia. High-cost medicines pose several challenges to the Australian National Medicines Policy, which aims to provide timely access to effective medicines at a cost individuals and the community can afford. Thus, novel restriction criteria were developed to encourage cost-effective use of bDMARDs. Government expenditure on bDMARD subsidies for RA treatment grew to about $383 million in 2014. Evidence that initiation and continuation criteria for bDMARDs meet usually applied cost-benefit criteria is lacking. The combined expenditure on tocilizumab, certolizumab pegol and golimumab (added to the Australian Government's Pharmaceutical Benefits Scheme in 2010) was $93 million in 2014, which is 210% over the initial estimate. Present and future challenges with regard to bDMARDs for RA and other high-cost drugs include improved expenditure predictions, monitoring of cost-effectiveness in relation to actual use and strategic development, regulation and use of biosimilars. Ten years of documentation on clinical and laboratory findings indicating eligibility to initiate and continue on bDMARDs remains un-used. These data represent an untapped opportunity to promote quality of use of bDMARDs and biosimilars and to improve cost predictions for high-cost drugs.