Aberrant B cell receptor signaling in circulating naïve and IgA+ memory B cells from newly-diagnosed autoantibody-positive rheumatoid arthritis patients.

OBJECTIVE: Altered B cell receptor (BCR) signaling has been implicated in the pathogenesis of rheumatoid arthritis (RA). Here we aimed to identify signaling aberrations in autoantibody-positive and autoantibody-negative RA patients by performing a comprehensive analysis of the BCR signaling cascade in different B cell subsets. METHODS: We first optimized phosphoflow cytometry for an in-depth analysis of BCR signaling across immunoglobulin isotypes in healthy donors. Subsequently, we compared BCR signaling in circulating B cell subsets from treatment-naïve, newly-diagnosed autoantibody-positive RA and autoantibody-negative RA patients and healthy controls (HCs). RESULTS: We observed subset-specific phosphorylation patterns of the BCR signalosome in circulating B cells from healthy donors. Compared with HCs, autoantibody-positive RA patients displayed enhanced responses to BCR stimulation for multiple signaling proteins, specifically in naïve and IgA+ memory B cells. Whereas in unstimulated healthy donor B cells, the phosphorylation status of individual signaling proteins showed only limited correlation, BCR stimulation enhanced the interconnectivity in phosphorylation within the BCR signalosome. However, this strong interconnectivity within the BCR signalosome in stimulated B cells from HCs was lost in RA, especially in autoantibody-positive RA patients. Finally, we observed strong correlations between SYK and BTK protein expression, and IgA and IgG anti-citrullinated protein antibody concentrations in serum from autoantibody-positive RA patients. CONCLUSION: Collectively, the isotype-specific analysis of multiple key components of the BCR signalosome identified aberrant BCR signaling responses in treatment-naïve autoantibody-positive RA patients, particularly in naïve B cells and IgA+ memory B cells. Our findings support differential involvement of dysregulated BCR signaling in the pathogenesis of autoantibody-positive and autoantibody-negative RA.

Responsiveness and sensitivity of PROMs to change in disease activity status in early and established rheumatoid arthritis.

OBJECTIVES: To determine whether patient reported outcome measures (PROMs) capturing activity limitations, health impact, pain, fatigue and work ability are responsive and sensitive to changes in disease activity status in patients with early and established rheumatoid arthritis (RA). METHODS: All early RA patients (n = 557) from the tREACH-trial and established RA patients (n = 188) from the TARA-trial were included. Both studies were multicentre, single-blinded trials with a treat-to-target management approach. The following PROMs were studied: Health Assessment Questionnaire Disability Index(HAQ-DI), morning stiffness severity, EQ-5D, general health, 36-item short form(SF-36), joint pain, fatigue and productivity loss. Mean changes in PROMs between two consecutive visits were compared with changes in disease activity status(remission, low disease activity and active disease) using linear mixed models and standardised response means. Additionally, the proportion of individual observations that showed an expected PROM response to disease activity status alterations was calculated. RESULTS: HAQ-DI, morning stiffness severity, general health, EQ-5D and joint pain demonstrated responsiveness to improvement or worsening of disease activity status in both early and established RA. SF-36 physical and mental component scale, fatigue and productivity loss did not show this effect in both groups. Across nearly all PROMs, the magnitude of change and the proportion of individual observations that reflect a shift from and to active disease remained low. CONCLUSION: HAQ-DI, morning stiffness severity, EQ-5D, general health and joint pain are responsive to disease activity status alterations on a group level in both early and established RA. For the individual patient the responsiveness of these PROMs is poor. CLINICAL TRIAL REGISTRATION: tREACH trial (www.isrctn.com, ISRCTN26791028) and TARA trial (www.onderzoekmetmensen.nl, NTR2754).

The course of cytokine and chemokine gene expression in clinically suspect arthralgia patients during progression to inflammatory arthritis.

OBJECTIVES: Autoantibody responses increase years before the onset of inflammatory arthritis (IA) and are stable during transitioning from clinically suspect arthralgia (CSA) to IA. Cytokine and chemokine levels also increase years before IA onset. However, the course in the at-risk stage of CSA during progression to disease or non-progression is unknown. To increase the understanding of processes mediating disease development, we studied the course of cytokine, chemokine and related receptors gene expression in CSA patients during progression to IA and in CSA patients who ultimately did not develop IA. METHODS: Whole-blood RNA expression of 37 inflammatory cytokines, chemokines and related receptors was determined by dual-colour reverse transcription multiplex ligation-dependent probe amplification in paired samples of CSA patients at CSA onset and either at IA development or after 24 months without IA development. ACPA-positive and ACPA-negative CSA patients developing IA were compared at CSA onset and during progression to IA. Generalised estimating equations tested changes over time. A false discovery rate approach was applied. RESULTS: None of the cytokine/chemokine genes significantly changed in expression between CSA onset and IA development. In CSA patients without IA development, G-CSF expression decreased (P = 0.001), whereas CCR6 and TNIP1 expression increased (P < 0.001 and P = 0.002, respectively) over a 2 year period. Expression levels in ACPA-positive and ACPA-negative CSA patients who developed IA were similar. CONCLUSION: Whole-blood gene expression of assessed cytokines, chemokines and related receptors did not change significantly from CSA to IA development. This suggests that changes in expression of these molecules may not be related to the final process of developing chronicity and may have occurred preceding CSA onset. Changes in gene expression in CSA patients without IA development may provide clues for processes related to resolution.

Ultrasound of the forefeet besides the hands in patients at risk for rheumatoid arthritis: is it worth the effort? A longitudinal cohort study.

OBJECTIVE: Ultrasound (US) can detect subclinical joint-inflammation in patients with clinically suspect arthralgia (CSA), which is valuable as predictor for rheumatoid arthritis (RA) development. In most research protocols both hands and forefeet are scanned, but it is unclear if US of the forefeet has additional value for predicting RA, especially since synovial hypertrophy in MTP-joints of healthy individuals is also common. To explore the possibility to omit scanning of the forefeet we determined if US of the forefeet is of additional predictive value for RA-development in CSA patients. METHODS: CSA patients of two independent cohorts underwent US of the hands and forefeet. We analyzed the association between RA-development and US-positivity for the full US-protocol, the full US-protocol with correction for Gray Scale(GS)-findings in the forefeet of healthy and the protocol without-forefeet. RESULTS: In total, 298 CSA patients were studied. In patients with a positive US, subclinical joint-inflammation was mostly present in the hands (90-86%). Only 10-14% of patients had subclinical joint-inflammation solely in the forefeet. US-positivity was associated with inflammatory arthritis development in both cohorts, with HRs 2.6(95%CI 0.9-7.5) and 3.1(95%CI 1.5-6.4) for the full protocol, 3.1(95%CI 1.3-7.7) and 2.7(95%CI 1.3-5.4) for the full US-protocol with correction, and 3.1(95%CI 1.4-6.9) and 2.8(95%CI 1.4-5.6) without the forefeet. AUROCs were equal across both cohorts. CONCLUSION: The forefeet can be omitted when US is used for the prediction of RA-development in CSA patients. This is due to the finding that subclinical joint-inflammation in the forefeet without concomitant inflammation in the hands is infrequent.

Intervention with methotrexate in patients with arthralgia at risk of rheumatoid arthritis to reduce the development of persistent arthritis and its disease burden (TREAT EARLIER): a randomised, double-blind, placebo-controlled, proof-of-concept trial.

BACKGROUND: Rheumatoid arthritis is the most common autoimmune disease worldwide and requires long-term treatment to suppress inflammation. Currently, treatment is started when arthritis is clinically apparent. We aimed to evaluate whether earlier intervention, in the preceding phase of arthralgia and subclinical joint inflammation, could prevent the development of clinical arthritis or reduce the disease burden. METHODS: We conducted a randomised, double-blind, placebo-controlled, proof-of-concept-trial at the Leiden University Medical Centre, Leiden, Netherlands. Adults aged 18 years or older with arthralgia clinically suspected of progressing to rheumatoid arthritis and MRI-detected subclinical joint inflammation were eligible for enrolment across 13 rheumatology outpatient clinics in the southwest region of the Netherlands and randomly assigned (1:1) to a single intramuscular glucocorticoid injection (120 mg) and a 1-year course of oral methotrexate (up to 25 mg/week), or placebo (single injection and tablets for 1 year). Participants and investigators were masked to group assignment. Follow-up continued for 1 year after the end of the 1-year treatment period. The primary endpoint was development of clinical arthritis (fulfilling the 2010 rheumatoid arthritis classification criteria or involving two or more joints) that persisted for at least 2 weeks. Patient-reported physical functioning, symptoms, and work productivity were secondary endpoints, which were measured every 4 months. Additionally, the course of MRI-detected inflammation was studied. All participants entered the intention-to-treat analysis. This trial is registered with EudraCT, 2014-004472-35, and the Netherlands Trial Register, NTR4853-trial-NL4599. FINDINGS: Between April 16, 2015, and Sept 11, 2019, 901 patients were assessed for eligibility and 236 were enrolled and randomly assigned to active treatment (n=119) or placebo (n=117). At 2 years, the frequency of the primary endpoint was similar between the groups (23 [19%] of 119 participants in the treatment group vs 21 [18%] of 117 in the placebo group; hazard ratio 0·81, 95% CI 0·45 to 1·48). Physical functioning improved more in the treatment group during the first 4 months and remained better than in the placebo group (mean between-group difference in Health Assessment Questionnaire disability index over 2 years: -0·09, 95% CI -0·16 to -0·03; p=0·0042). Similarly, pain (on scale 0-100, mean between-group difference: -8, 95% CI -12 to -4; p<0·0001), morning stiffness of joints (-12, -16 to -8; p<0·0001), presenteeism (-8%, -13 to -3; p=0·0007), and MRI-detected joint inflammation (-1·4 points, -2·0 to -0·9; p<0·0001) showed sustained improvement in the treatment group compared with the placebo group. The number of serious adverse events was equal in both groups; adverse events were consistent with the known safety profile for methotrexate. INTERPRETATION: Methotrexate, the cornerstone treatment of rheumatoid arthritis, initiated at the pre-arthritis stage of symptoms and subclinical inflammation, did not prevent the development of clinical arthritis, but modified the disease course as shown by sustained improvement in MRI-detected inflammation, related symptoms, and impairments compared with placebo. FUNDING: Dutch Research Council (NWO; Dutch Arthritis Society).

Rheumatoid arthritis presenting with mono- or oligo-arthritis and high VAS remains most fatigued during 5-years follow-up.

OBJECTIVES: The severity of fatigue in rheumatoid arthritis (RA) has hardly improved in recent decades, leaving a large unmet need. Fortunately, not all RA-patients suffer from persistent fatigue, but the subgroup of patients who suffer the most is insufficiently recognizable at diagnosis. As disease activity is partly coupled to fatigue, Disease-Activity-Score (DAS)-components may associate with the course of fatigue. We aimed to identify the RA-patients who remain fatigued by studying DAS-components at diagnosis in relation to the course of fatigue over a 5-year follow-up period in two independent early RA-cohorts. METHODS: 1560 consecutive RA-patients included in the Leiden Early Arthritis Cohort and 415 RA-patients included in the tREACH-Cohort were studied. Swollen joint count, tender joint count, ESR and Patient Global Assessment (Visual Analogue Scale(VAS),0-100 mm) were studied in relation to fatigue(VAS, 0-100mm) during 5-years using linear mixed models. RESULTS: Higher TJC and PGA at diagnosis were associated with a more severe course of fatigue. The SJC, in contrast, showed an inverse association; patients with mono- or oligo-arthritis at diagnosis remained more fatigued. The combination of aforementioned characteristics revealed that patients presenting with a mono- or oligo-arthritis and PGA ≥ 50 remained the most fatigued over time(+20mm vs polyarthritis with PGA < 50), whilst the DAS-course over time was not different. This subgroup comprised 14% of the early RA-population. Data from the tREACH-cohort showed similar findings. CONCLUSION: RA-patients who remain the most fatigued are characterized by mono- or oligo-arthritis and high PGA(VAS ≥ 50) at diagnosis. This understanding may enable early-intervention with non-pharmacological approaches in dedicated patient groups.

Patient-reported swelling in arthralgia patients at risk for rheumatoid arthritis: is it of value?

OBJECTIVE: Patients with Clinically Suspect Arthralgia (CSA) are at risk for developing Rheumatoid Arthritis (RA). These patients often report joint swelling while this is not objectified by physical examination. To explore the value of patient-reported swelling in CSA, we aimed to determine its association with subclinical joint-inflammation on imaging and RA-development. METHODS: In two independent, similarly designed CSA-cohorts from the Netherlands, symptomatic patients at risk for RA were studied. At baseline, patients indicated whether they had experienced swelling in hand joints. Subclinical joint-inflammation was assessed with MRI or ultrasound (US). Patients were followed for inflammatory arthritis development. RESULTS: In total, 534 CSA-patients from two independent cohorts were studied, patient-reported swelling was present in 57% in cohort 1, and in 43% in cohort 2. In both cohorts patient-reported swelling was associated with subclinical joint-inflammation. Using MRI, it associated specifically with tenosynovitis (OR 3.7 (95%CI 2.0-6.9)) and when using US with synovitis (OR 2.3 (95%CI 1.04-5.3)). CSA-patients with self-reported swelling at baseline developed arthritis more often, with hazard ratios of 3.7 (95%CI 2.0-6.9) and 3.4 (95%CI 1.4-8.4) in cohort 1 and 2, respectively. This was independent of clinical predictors (e.g. morning stiffness), autoantibody-positivity and US-detected subclinical joint-inflammation. However, when corrected for MRI-detected subclinical joint-inflammation, self-reported swelling was no longer an independent predictor. CONCLUSION: Patient-reported joint swelling in CSA relates to subclinical joint-inflammation and is an independent risk factor for RA-development, but it is less predictive than the presence of MRI-detected subclinical joint-inflammation.

Machine learning identifies a profile of inadequate responder to methotrexate in rheumatoid arthritis.

OBJECTIVES: Around 30% of patients with RA have an inadequate response to MTX. We aimed to use routine clinical and biological data to build machine learning models predicting EULAR inadequate response to MTX and to identify simple predictive biomarkers. METHODS: Models were trained on RA patients fulfilling the 2010 ACR/EULAR criteria from the ESPOIR and Leiden EAC cohorts to predict the EULAR response at 9 months (± 6 months). Several models were compared on the training set using the AUROC. The best model was evaluated on an external validation cohort (tREACH). The model's predictions were explained using Shapley values to extract a biomarker of inadequate response. RESULTS: We included 493 therapeutic sequences from ESPOIR, 239 from EAC and 138 from tREACH. The model selected DAS28, Lymphocytes, Creatininemia, Leucocytes, AST, ALT, swollen joint count and corticosteroid co-treatment as predictors. The model reached an AUROC of 0.72 [95% CI (0.63, 0.80)] on the external validation set, where 70% of patients were responders to MTX. Patients predicted as inadequate responders had only 38% [95% CI (20%, 58%)] chance to respond and using the algorithm to decide to initiate MTX would decrease inadequate-response rate from 30% to 23% [95% CI: (17%, 29%)]. A biomarker was identified in patients with moderate or high activity (DAS28 > 3.2): patients with a lymphocyte count superior to 2000 cells/mm3 are significantly less likely to respond. CONCLUSION: Our study highlights the usefulness of machine learning in unveiling subgroups of inadequate responders to MTX to guide new therapeutic strategies. Further work is needed to validate this approach.

Clinically suspect arthralgia patients with a low educational attainment have an increased risk of developing inflammatory arthritis.

OBJECTIVES: Cross-sectional studies have shown that rheumatoid arthritis is more prevalent among people with a lower educational attainment. No longitudinal data are present on educational attainment in the at-risk phase of clinically suspect arthralgia (CSA). We therefore analysed the association between educational attainment and progression from CSA to inflammatory arthritis (IA), and performed mediation analysis with subclinical joint inflammation to elucidate pathways of this association. METHODS: A total of 521 consecutive patients presenting with CSA were followed for IA development during median 25 months. Educational attainment was defined as low (lower secondary vocational education), intermediate or high (college/university education). Subclinical inflammation in hand and foot joints was measured at presentation with contrast enhanced 1.5 T-MRI. Cox-regression was used to analyse IA development per educational attainment. A three-step mediation analysis evaluated whether subclinical joint inflammation was intermediary in the path between educational attainment and IA development, before and after age correction. Association between educational attainment and IA development was verified in an independent CSA cohort. RESULTS: Low educational attainment was associated with increased IA development (HR = 2.35, 95% CI = 1.27, 4.33, P = 0.006), independent of BMI and current smoking status (yes/no). Moreover, patients with a low educational attainment had higher levels of subclinical inflammation, which also was associated with IA development. Partial mediation effect of subclinical inflammation was observed in the relationship between education and IA development. Low educational attainment was also associated with increased IA development in the validation cohort (HR = 5.72, 95% CI = 1.36, 24.08, P = 0.017). CONCLUSION: This is the first study providing evidence that lower educational attainment is associated with a higher risk of progressing from arthralgia to IA. This effect was partially mediated by subclinical joint inflammation.

Work participation is reduced during the development of RA, months before clinical arthritis manifests.

OBJECTIVES: We investigated whether work participation is affected in patients with arthralgia during transition to RA. Arthralgia patients with symptom resolution and early RA patients at diagnosis were used as a reference. METHODS: Three groups of patients were studied: arthralgia patients converting to RA (n = 114), arthralgia patients with spontaneous symptom resolution (n = 57), and early RA patients (n = 617). Both presenteeism (i.e. working while sick, scale 0-10) and absenteeism (i.e. sick leave) were taken into account. Work ability 1 year prior to clinical arthritis was estimated (in absolute numbers). The course of work restriction over time was studied using linear mixed models (ß coefficient; delta per month) within each patient group. RESULTS: One-year prior to the development of clinical arthritis, mean presenteeism was 7.0 (95% CI 5.8, 8.1) in patients with arthralgia, indicating 30% loss, and further worsened to 6.1 (95% CI 5.3, 6.6) at RA diagnosis, thus indicating 39% loss. In early RA patients, presenteeism improved over time after DMARD initiation (ß 0.052 per month 95% CI 0.042, 0.061, P < 0.0001). Presenteeism also improved in arthralgia patients who achieved spontaneous symptom resolution (ß 0.063 per month, 95% CI 0.024, 0.10, P = 0.002). Absenteeism did not change significantly in arthralgia patients, but did improve in RA after DMARD-start. ACPA stratification revealed similar results. CONCLUSION: In the months preceding RA, presenteeism was already apparent, and it worsened further during progression to clinical arthritis and diagnosis. This underlines the relevance of the symptomatic pre-RA phase for patients. The observed reversibility in arthralgia patients with symptom resolution may suggest that intervention in pre-RA could improve work participation.

An ultrasound negative for subclinical synovitis in arthralgia patients: is it helpful in identifying those not developing arthritis?

OBJECTIVE: To investigate the negative predictive value (NPV) of musculoskeletal US (MSUS) in arthralgia patients at risk for developing inflammatory arthritis. METHODS: An MSUS examination of hands and feet was performed in arthralgia patients at risk for inflammatory arthritis in four independent cohorts. Patients were followed for one-year on the development of inflammatory arthritis. Subclinical synovitis was defined as greyscale ≥2 and/or power Doppler ≥1. NPVs were determined and compared with the prior risks of not developing inflammatory arthritis. Outcomes were pooled using meta-analyses and meta-regression analyses. In sensitivity analyses, MSUS imaging of tender joints only (rather than the full US protocol) was analysed and ACPA stratification applied. RESULTS: After 1 year 78, 82, 77 and 72% of patients in the four cohorts did not develop inflammatory arthritis. The NPV of a negative US was 86, 85, 82 and 90%, respectively. The meta-analysis showed a pooled non-inflammatory arthritis prevalence of 79% (95% CI 75%, 83%) and a pooled NPV of 86% (95% CI 81, 89%). Imaging tender joints only (as generally done in clinical practice) and ACPA stratification showed similar results. CONCLUSION: A negative US result in arthralgia has a high NPV for not developing inflammatory arthritis, which is mainly due to the high a priori risk of not developing inflammatory arthritis. The added value of a negative US (<10% increase) was limited.

Subclinical synovitis in arthralgia: how often does it result in clinical arthritis? Reflecting on starting points for disease-modifying anti-rheumatic drug treatment.

OBJECTIVES: According to guidelines, clinical arthritis is mandatory for diagnosing RA. However, in the absence of clinical synovitis, imaging-detected subclinical synovitis is increasingly used instead and is considered as a starting point for DMARD therapy. To search for evidence we studied the natural course of arthralgia patients with subclinical synovitis from three longitudinal cohorts and determined the frequencies of non-progression to clinically apparent inflammatory arthritis (IA) (i.e. 'false positives'). METHODS: Subclinical synovitis in the hands or feet of arthralgia patients was visualized with US (two cohorts; definition: greyscale ≥2 and/or power Doppler ≥1) or MRI (one cohort; definition: synovitis score ≥1 by two readers). Patients were followed for 1 year on for IA development; two cohorts also had 3 year data. Analyses were stratified for ACPA. RESULTS: Subclinical synovitis at presentation was present in 36%, 41% and 31% in the three cohorts. Of the ACPA-positive arthralgia patients with subclinical synovitis, 54%, 44% and 68%, respectively, did not develop IA. These percentages were even higher in the ACPA-negative arthralgia patients: 66%, 85% and 89%, respectively. Similar results were seen after 3 years of follow-up. CONCLUSION: Replacing clinical arthritis with subclinical synovitis to identify RA introduces a high false-positive rate (44-89%). These data suggest an overestimation regarding the value of ACPA positivity in combination with the presence of subclinical synovitis in patients with arthralgia, which harbours the risk of overtreatment if DMARDs are initiated in the absence of clinical arthritis.

Inadequate response to treat-to-target methotrexate therapy in patients with new-onset rheumatoid arthritis: development and validation of clinical predictors.

OBJECTIVE: To identify and validate clinical baseline predictors associated with inadequate response (IR) to methotrexate (MTX) therapy in newly diagnosed patients with rheumatoid arthritis (RA). METHODS: In U-Act-Early, 108 disease-modifying antirheumatic drug (DMARD)-naive patients with RA were randomised to initiate MTX therapy and treated to target until sustained remission (disease activity score assessing 28 joints (DAS28) <2.6 with four or less swollen joints for ≥24 weeks) was achieved. If no remission, hydroxychloroquine was added to the treatment regimen (ie, 'MTX+') and replaced by tocilizumab if the target still was not reached thereafter. Regression analyses were performed to identify clinical predictors for IR, defined as needing addition of a biological DMARD, to 'MTX+'. Data from the treatment in the Rotterdam Early Arthritis Cohort were used for external validation of the prediction model. RESULTS: Within 1 year, 56/108 (52%) patients in U-Act-Early showed IR to 'MTX+'. DAS28 (adjusted OR (ORadj) 2.1, 95% CI 1.4 to 3.2), current smoking (ORadj 3.02, 95% CI 1.1 to 8.0) and alcohol consumption (ORadj 0.4, 95% CI 0.1 to 0.9) were identified as baseline predictors. The area under the receiver operator characteristic curve (AUROC) of the prediction model was 0.75 (95% CI 0.66 to 0.84); the positive (PPV) and negative predictive value (NPV) were 65% and 80%, respectively. When applying the model to the validation cohort, the AUROC slightly decreased to 0.67 (95% CI 0.55 to 0.79) and the PPV and NPV to 54% and 80%, respectively. CONCLUSION: Higher DAS28, current smoking and no alcohol consumption are predictive factors for IR to step-up 'MTX+' in DMARD-naive patients with new-onset RA. TRIAL REGISTRATION: NCT01034137; Post-results, ISRCTN26791028; Post-results.

Best cost-effectiveness and worker productivity with initial triple DMARD therapy compared with methotrexate monotherapy in early rheumatoid arthritis: cost-utility analysis of the tREACH trial.

OBJECTIVE: To evaluate direct and indirect costs per quality adjusted life year (QALY) for different initial treatment strategies in very early RA. METHODS: The 1-year data of the treatment in the Rotterdam Early Arthritis Cohort trial were used. Patients with a high probability (>70%) according to their likelihood of progressing to persistent arthritis, based on the prediction model of Visser, were randomized into one of following initial treatment strategies: (A) initial triple DMARD therapy (iTDT) with glucocorticoids (GCs) intramuscular (n = 91); (B) iTDT with an oral GC tapering scheme (n = 93); and (C) initial MTX monotherapy (iMM) with GCs similar to B (n = 97). Data on QALYs, measured with the Dutch EuroQol, and direct and indirect cost were used. Direct costs are costs of treatment and medical consumption, whereas indirect costs are costs due to loss of productivity. RESULTS: Average QALYs (sd) for A, B and C were, respectively, 0.75 (0.12), 0.75 (0.10) and 0.73 (0.13) for Dutch EuroQol. Highest total costs per QALY (sd) were, respectively, €12748 (€18767), €10 380 (€15 608) and €17 408 (€21 828) for strategy A, B and C (P = 0.012, B vs C). Direct as well as indirect costs were higher with iMM (strategy C) compared with iTDT (strategy B). Higher direct costs were due to ∼40% more biologic usage over time. Higher indirect costs, on the other hand, were caused by more long-term sickness and reduction in contract hours. iTDT was >95% cost-effective across all willingness-to-pay thresholds compared with iMM. CONCLUSION: iTDT was more cost-effective and had better worker productivity compared with iMM.

Methotrexate polyglutamates in erythrocytes are associated with lower disease activity in patients with rheumatoid arthritis.

OBJECTIVE: To investigate if erythrocyte-methotrexate-polyglutamate (MTX-PG) concentrations in patients with rheumatoid arthritis (RA) are associated with disease activity or adverse events. METHODS: We used a longitudinal study design with two cohorts. The derivation cohort included 102 and the validation cohort included 285 patients with RA on MTX. We measured erythrocyte-MTX-PG with 1-5 glutamate residues at 3 months, 6 months and 9 months after MTX start with a liquid chromatography (LC)-mass spectrometry (MS)/MS assay. Outcomes were disease activity score in 28 joints (DAS28) and adverse events. Longitudinal associations of MTX-PG concentrations after 3 months, 6 months and 9 months with DAS28 were tested with a linear mixed model adjusted for age, gender, baseline DAS28, MTX dose and comedication. RESULTS: In the derivation cohort, mean DAS28 decreased from 4.26 (SE=0.14) at baseline to 2.72 (SE=0.13) after 9 months. Thirty per cent of patients in the derivation cohort experienced more than three adverse events after 3 months, which decreased to 18% after 9 months. In the validation cohort, DAS28 and adverse events were comparable with the derivation cohort. In the derivation cohort, MTX-PG1 (ß=-0.005), MTX-PG2 (ß=-0.022), MTX-PG3 (ß=-0.007) and total MTX-PG (ß=-0.004) were associated (p<0.05) with lower DAS28 over 9 months. In the validation cohort, MTX-PG2 (ß=-0.015), MTX-PG3 (ß=-0.010), MTX-PG4 (ß=-0.008) and total MTX-PG (ß=-0.003) were associated with lower DAS28 over 9 months. None of the MTX-PGs was associated with adverse events. CONCLUSIONS: In this first longitudinal study, we showed that an increase in erythrocyte-MTX-PG concentration was associated with a decreased DAS28 over 9 months in two cohorts, and is therefore a potential tool for therapeutic drug monitoring of MTX in RA.