The impact of preoperative sarcopenia on postoperative ileus following colorectal cancer surgery

PURPOSE

Sarcopenia is associated with poor short- and long-term patient outcomes following colorectal surgery. Despite postoperative ileus (POI) being a major complication following colorectal surgery, the predictive value of sarcopenia for POI is unclear. We assessed the association between sarcopenia and POI in patients with colorectal cancer.

METHODS

Elective colorectal cancer surgery patients were retrospectively included (2018-2022). The cross-sectional psoas area was calculated using preoperative staging imaging at the level of the 3rd lumbar vertebrae. Sarcopenia was determined using gender-specific cut-offs. The primary outcome POI was defined as not achieving GI-2 by day 4. Demographics, operative characteristics, and complications were compared via univariate and multivariate analyses.

RESULTS

Of 297 patients, 67 (22.6%) were sarcopenic. Patients with sarcopenia were older (median 74 (IQR 67-82) vs. 69 (58-76) years, p < 0.001) and had lower body mass index (median 24.4 (IQR 22.2-28.6) vs. 28.8 (24.9-31.9) kg/m2, p < 0.001). POI was significantly more prevalent in patients with sarcopenia (41.8% vs. 26.5%, p = 0.016). Overall rate of complications (85.1% vs. 68.3%, p = 0.007), Calvien-Dindo grade > 3 (13.4% vs. 10.0%, p = 0.026) and length of stay were increased in patients with sarcopenia (median 7 (IQR 5-12) vs. 6 (4-8) days, p = 0.013). Anastomotic leak rate was higher in patients with sarcopenia although the difference was not statistically significant (7.5% vs. 2.6%, p = 0.064). Multivariate analysis demonstrated sarcopenia (OR 2.0, 95% CI 1.1-3.8), male sex (OR 1.9, 95% CI 1.0-3.5), postoperative hypokalemia (OR 3.2, 95% CI 1.6-6.5) and increased opioid use (OR 2.4, 95% CI 1.3-4.3) were predictive of POI.

CONCLUSION

Sarcopenia demonstrates an association with POI. Future research towards truly identifying the predictive value of sarcopenia for postoperative complications could improve informed consent and operative planning for surgical patients.

Relevance of necroptosis in the hearts subjected to acute versus chronic ischemia/reperfusion injury

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): Slovak Research and Development Agency

Medical Research Council Grant

Necroptosis, a necrosis-like programmed cell death modality dependent on the activity of receptor-interacting protein kinase 3 (RIP3) and mixed lineage domain kinase domain-like pseudokinase (MLKL), plays a prominent role in mediating myocardial ischemia/reperfusion injury. However, the extent to which necroptosis contributes to such damage under short and long reperfusion has not been evaluated in detail. In Wistar rat hearts, subjected to global 30-min ischemia followed by an acute 10-min reperfusion period, with compromised cardiac function, no changes in the protein expression of the main necroptotic markers (pThr231/Ser232-RIP3, MLKL) were found. Likewise, the non-canonical pathways of necroptosis involving Ca2+/calmodulin dependent protein kinase II–mitochondrial permeability transition pore (CaMKII–mPTP) or phosphoglycerate mutase 5–dynamin-related protein 1 (PGAM5–Drp1) axes were unlikely affected by such short reperfusion. In contrast, hearts subjected to global 30-min ischemia followed by a prolonged 40-min reperfusion period exhibited worsened hemodynamic parameters what was accompanied by the increased levels of RIP3, pSer229-RIP3 and MLKL. Moreover, this reperfusion period induced MLKL translocation to the plasma membrane, indicating necroptosis execution with resultant very likely cell disruption. Similarly, activated necroptosis, evidenced by the higher levels of proteins of the canonical pathway, has been suggested to contribute to the pathogenesis of post-infarction heart failure (30-min ischemia, 42-day reperfusion). Collectively, these findings suggest that short reperfusion seems to be insufficient to induce necroptosis in the heart and the molecular mechanisms being activated during the longer reperfusion phase are needed to promote necroptotic cell dying. Therefore, inhibition of necroptosis might represent a cardioprotective strategy in the settings of chronic, but not acute myocardial ischemia/reperfusion injury.

POS0145 CLINICAL RESPONSE TO RITUXIMAB IS ASSOCIATED WITH PREVENTION OF B-CELL DRIVEN SALIVARY GLAND INFLAMMATION AND EPITHELIAL RESTORATION AS REVEALED BY MOLECULAR PATHOLOGY: RESULTS FROM THE TRACTISS TRIAL IN PRIMARY SJOGREN’S SYNDROME

Background

The TRial for Anti-B-Cell Therapy In patients with pSS (TRACTISS) is the largest multi-centre, placebo-controlled, phase-III trial with the administration of 2 cycles of Rituximab (RTX) or placebo at week 0 and 24, with trial clinical endpoints at week 48. Despite the primary endpoints (30% reduction in fatigue or oral dryness) were not met, RTX treated patients showed an improvement in secondary endpoints, such as unstimulated whole salivary flow (UWSF), and salivary gland (SG) total ultrasound score1,2. Additionally, recent post-hoc analysis of TRACTISS using novel CRESS composite endpoints3, highlighted a significantly increased response rate in the RTX vs placebo arm.

Objectives

To perform the first longitudinal analysis of matched transcriptomic and histological data of SG biopsies of pSS patients treated with RTX vs placebo at 3 time points, over 48 weeks, from the TRACTISS cohort, in order to identify mechanisms of response/resistance to B cell depletion.

Methods

29 pSS patients randomised to RTX or placebo arm consented for labial SG biopsies at week 0, 16 and 48. Patients received two 1000mg cycles of RTX or placebo at week 0 and 24. SG focus score, inflammatory aggregate area fraction, B-cells (CD20+), T-cells (CD3+), follicular dendritic cells (FDCs) (CD21+) and plasma cells (CD138+) density were assessed using quantitative digital image analysis. RNA sequencing with deconvolution and pathway analysis was performed to identify genes signatures and consensus gene modules as biomarkers of disease evolution and response/resistance to therapy.

Results

Placebo-treated SGs showed worsening of SG inflammation highlighted by the increment of aggregate size, B-cell density, development of new FDC networks, and a higher ectopic GC prevalence over 48 weeks, compared to RTX-treated patients. No difference in focus score, total T-cell and plasma cell infiltration was observed. RTX downregulated genes involved in immune cell recruitment and inflammatory aggregate organisation (e.g. CXCL13, CCR7 and PDCD1). Gene signature-based analysis of 35 immune cell types using XCell highlighted how RTX blocked class-switched and memory-B-cells accumulation in SGs over 48 weeks. Pathway analyses confirmed the downregulation of leukocyte migration, MHC-II antigen presentation, and T-cell co-stimulation immunological pathways, such as the CD40 receptor complex pathway. Among RTX-treated patients, only CRESS-responders demonstrated prevention of worsening B cell-driven molecular pathology signatures over time and a significant improvement in UWSF, in parallel with the upregulation of molecular pathways associated to SG restoration of the glandular epithelium. None of the above effects were observed at week 16 after the first RTX cycle.

Conclusion

Two RTX infusions repeated at week 24 exerted beneficial effects on labial SG inflammatory infiltration in pSS by downregulating genes involved in immune cell recruitment, activation and organisation in ectopic GCs. Conversely, all the above parameters showed significant evolution in placebo treated patients over 48 weeks demonstrating progression of SG immunopathology. Clinical responders to RTX based on CRESS response criteria were characterised by preservation of exocrine function which appear driven by SG epithelial restoration.

References

[1]Fisher, B. A. et al. Effect of rituximab on a salivary gland ultrasound score in primary Sjögren’s syndrome: results of the TRACTISS randomised double-blind multicentre substudy. Ann. Rheum. Dis.77, 412–416 (2018).

[2]Bowman, S. J. et al. Randomized Controlled Trial of Rituximab and Cost-Effectiveness Analysis in Treating Fatigue and Oral Dryness in Primary Sjögren’s Syndrome. Arthritis Rheumatol.69, 1440–1450 (2017).

[3]Arends, S. et al. Composite of Relevant Endpoints for Sjögren’s Syndrome (CRESS): development and validation of a novel outcome measure. Lancet Rheumatol.3, e553–e562 (2021).

Disclosure of Interests

None declared

OP0085 CELL LINEAGE-SPECIFIC TRANSCRIPT DECONVOLUTION OF SYNOVIAL BIOPSIES FROM THE R4RA TRIAL IDENTIFIES CELL POPULATIONS ASSOCIATED WITH RESPONSE TO RITUXIMAB AND TOCILIZUMAB

Background

The R4RA trial, the first biopsy-based randomised trial in TNF-i inadequate responder patients with Rheumatoid Arthritis, showed that molecular stratification of RA synovial tissue was associated with clinical response, demonstrating that, in patients with low/absent B-cell lineage signature in synovial-tissue, tocilizumab is superior to rituximab1.

Objectives

Here, we aimed to perform cell-transcript deconvolution of pre-and post-treatment synovial biopsies from the R4RA trial.

Methods

A total of 164 patients underwent pre-treatment synovial biopsy (US-guided or arthroscopic) prior to randomization 1:1 to rituximab (83) or tocilizumab (81). 65 patients had a repeat biopsy at 16 weeks when clinical response was assessed using Clinical Disease Activity Index (CDAI) 50% improvement. RNA extracted from a minimum of 6 synovial samples/patient underwent RNA-sequencing and the abundance of tissue-infiltrating immune and stromal cell populations was estimated using the Microenvironment Cell Populations-counter (MCP-counter) method (Figure 1a).

Results

At baseline, while synovial semiquantitative immunohistochemistry scores did not differ between CDAI50% responders and non-responders, both for rituximab and tocilizumab, MCP-counter analysis showed significantly higher CD8 T-cells in responders to rituximab and higher macrophage-monocytes and myeloid dendritic cells (mDC) in responders to tocilizumab (Figure 1b). Moreover, when patients were classified according to MCP-counter scores, B-cell poor patients (MCP-counter B cell score <median value) showed significantly higher response rates to tocilizumab, while no difference was found in B-cell rich patients (Figure 1c). In contrast, macrophage and myeloid dendritic cell (mDC) rich individuals showed higher responses to tocilizumab (Figure 1d). Combined scores for lymphoid and myeloid cells demonstrated that patients poor in B-cells but rich in macrophages/mDC had a significantly higher response to tocilizumab (77% responders to tocilizumab vs 14% responders to rituximab, p=0.017, OR 16.48, 95%CI 1.29-1000.5) (Figure 1e). By analysing disease activity over time from baseline to week 16, we found a statistically significant interaction effect between treatments and time in B-cell poor (p=0.003), T-cell poor (p=0.022), mDC rich (p=0.029) and B-cell poor/Macrophages-mDC rich patients (p=0.006) (Figure 1f-g-h). Finally, by applying MCP-counter on matched pre-and post-treatment biopsies, rituximab-treated patients showed a significant reduction of B-cells, T-cells and monocyte/macrophages, while tocilizumab-treated patients showed a significant reduction of monocyte/macrophages, T-cells, but also neutrophils, myeloid dendritic cells and, interestingly, an increase in fibroblast signature (Figure 1i).

Conclusion

In silico deconvolution of the synovial tissue identify pre-treatment lymphoid cell lineages associated with response to rituximab and myeloid cells for tocilizumab. The longitudinal analysis of matched pre- and post-treatment synovial biopsies indicated that both medications have an effect on synovial immune cells, but tocilizumab can also affect stromal cells.

References

[1]Humby et al. Rituximab versus tocilizumab in anti-TNF inadequate responder patients with rheumatoid arthritis (R4RA): 16-week outcomes of a stratified, biopsy-driven, multicentre, open-label, phase 4 randomised controlled trial Lancet. 2021 Jan 23;397(10271):305-317. doi: 10.1016/S0140-6736(20)32341-2.

Acknowledgements

We would like to thank all patients and the R4RA recruiting centres and principal investigators http://www.r4ra-nihr.whri.qmul.ac.uk/recruiting_centres.php We would also like to acknowledge the UK National Institute of Health Research for funding the R4RA trial (grant reference: 11/100/76) and Versus Arthritis for providing infrastructure support through the Experimental Arthritis Treatment Centre (grant number: 20022).

Disclosure of Interests

None declared.

OP0077 SYNOVIAL RNA-SEQ ANALYSIS OF THE R4RA TRIAL IDENTIFIES SIGNATURES OF TREATMENT RESISTANCE AND REFRACTORY STATE IN RHEUMATOID ARTHRITIS

Background

Although up to 5-20% of rheumatoid arthritis (RA) patients do not respond to all current medications including biologic therapies, relatively little is known about the underlying pathogenic mechanisms driving non-response. In the first biopsy-driven randomized clinical trial in RA (R4RA)1, patients, in whom synthetic-DMARDs and at least one anti-TNF drug were not effective, were randomised 1:1 to rituximab (RTX) or tocilizumab (TOC) with a balanced stratification based on their synovial B-cell rich/poor signature, and response was assessed at 16 weeks. Non-responders were subsequently allowed to switch to the alternative drug with 48-week follow-up.

Objectives

Investigate mechanisms of response and non-response to RTX and TOC through deep molecular (RNA-Sequencing) profiling of synovial tissue.

Methods

RNA-Seq from baseline synovial tissue biopsies of patients who received RTX (n=88) or TOC (n=94) at any point in the trial was analysed for differentially expressed genes and associated modules between responders and non-responders. Response was defined as 50% improvement in clinical disease activity index (CDAI) score. Patients who had received both drugs during the trial were subdivided into RTX only responders (pro-RTX, n=9), TOC only responders (pro-TOC, n=12) and refractory patients (no response to both RTX & TOC, n=32) and analysed for differential gene expression and performed gene module analysis.

Results

6625 genes were significantly differentially expressed between RTX responders compared to non-responders, with a predominance of antigen presentation as well as T- and B-cell genes being associated with response, while non-response was linked to fibroblast associated genes. Comparison between TOC responders and non-responders identified fewer (85) differentially expressed genes, however lymphocyte and immunoglobulin genes were also high in the synovial tissue of TOC responders similar to RTX responders, while non-responder genes and modules also included a fibroblast signature.

The cross-over study design enabled comparison of rituximab-specific responders (pro-RTX), tocilizumab-specific responders (pro-TOC) and refractory patients (non-responders to both RTX & TOC, n=32) in a 3-way analysis (see Figure 1). This identified 1980 genes upregulated both in pro-RTX and pro-TOC patients, 175 genes exclusive to the pro-RTX group and 306 to the pro-TOC group, while 1277 genes were exclusive to the refractory group. While leukocyte modules and genes dominated RTX & TOC response, the refractory state was strongly associated with fibroblast genes and modules. We confirmed the observed expansion of fibroblasts from the RNA-Seq data by immunohistochemistry showing the presence of DKK3+ sublining fibroblasts in refractory rather than responder patients.

Conclusion

We provide novel insights into the cellular and molecular pathways underpinning multi-biologic resistance that define a refractory RA phenotype, characterised by a stromal/fibroblast signature.

References

[1]Humby, F., et al. Lancet (2021)

Acknowledgements

We would like to thank all patients and the R4RA recruiting centres and principal investigators http://www.r4ra-nihr.whri.qmul.ac.uk/recruiting_centres.php We would also like to acknowledge the UK National Institute of Health Research for funding the R4RA trial (grant reference: 11/100/76) and Versus Arthritis for providing infrastructure support through the Experimental Arthritis Treatment Centre (grant number: 20022).

Disclosure of Interests

None declared.

POS0138 RHEUMATOID SYNOVIAL FIBROBLASTS DISPLAY IMPRINTED MEMORY OF THEIR SYNOVIAL ENDOTYPE WHICH CAN BE PLASTICALLY MODULATED BY B-CELLS CROSSTALK

Background

Despite advances in the treatment of Rheumatoid Arthritis (RA), synthetics and biologicals drugs are ineffective in ~40% of patients. The origin of this refractoriness is unclear, but several clues point at the synovial microenvironment (SE) and the relative cellular heterogeneity between patients. We previously described the existence of different RA endotypes such as the lympho-myeloid, LM, which is B-cell rich and the fibroid-paucimmune, FPI, which is devoid of B-cells. While there is clear evidence that the crosstalk between stromal and immune cells in rheumatoid joints is critical for the perpetuation of chronic inflammation and autoimmunity, it is currently unknown whether transcriptional signatures identified in synovial fibroblasts (SFs) derived from different RA endotypes are driven by “imprinted” properties of the SFs or are shaped by the interaction with infiltrating immune cells in the RA joints.

Objectives

I) to identify “imprinted” vs “inducible” RASFs signatures trough the comparison of freshly isolated SFs and primary established SFs cultures obtained from LM vs FPI RA synovial biopsies and ii) to investigate the identified RASF signature as predictive biomarkers of disease evolution and of response to conventional and biological DMARDs.

Methods

We performed flowcytometry and single cell RNA sequencing (sc-RNAseq) on SFs obtained from LM and FPI biopsies, in isolation or in co-culture with RA B cells. Next, supernatant has been screened trough Multiplex and ELISA. Furthermore, we compared our results to publicly available sc-RNAseq datasets on freshly isolated SFs and to our bulk-RNAseq data from clinical trials patients.

Results

Hierarchical clustering from sc-RNAseq transcriptional profiling of LM vs FPI RASF - after several cell passages - identified profoundly different gene signatures: whereby LM-RASF were characterised by genes involved in inflammation, proteoglycan formation and integrin binding, FPI-RASF were defined by genes related to collagen biosynthesis. Comparing the above signatures with those of freshly isolated RASF we identified both imprinted (i.e. maintained through several in vitro passages) and inducible (i.e. loss after long term culture) gene signatures. Notably, RA B-cells co-cultured with FPI-RASF profoundly altered the FPI-RASF transcriptional profile including the ex-novo expression of gene signatures typical of LM-RASF. Consensus gene modules constructed on LM vs FPI RASF imprinted gene signatures could be tracked in longitudinal whole tissue bulk RNA-seq data obtained from both early arthritis and established RA and were associated with synovial pathotype-specific histological and clinical features. Finally, modulation of FPI-RASF related genes following B-cell depletion identified poor responders to Rituximab in the R4RA randomised clinical trial.

Conclusion

Our work demonstrates that RASFs from different endotypes display imprinted memory of their original synovial tissue when maintained in culture over several months. We also demonstrated that imprinted memory typical of RASF isolated from B-cell rich LM synovial tissues can be dynamically modulated in FPI RASF following crosstalk with RA B cells. Finally, consensus gene modules based on FPI vs LM RASF-gene signatures were able inform on response/resistance to targeted biologic therapies.

References

[1]Lewis, M. J. et al. Molecular Portraits of Early Rheumatoid Arthritis Identify Clinical and Treatment Response Phenotypes. Cell Rep (2019)

[2]Humby, F. et al. Synovial cellular and molecular signatures stratify clinical response to csDMARD therapy and predict radiographic progression in early rheumatoid arthritis patients. Ann Rheum Dis (2019)

[3]Zhang, F. et al. Defining inflammatory cell states in rheumatoid arthritis joint synovial tissues by integrating single-cell transcriptomics and mass cytometry. Nat Immunol (2019)

[4]Humby, F. et al. Rituximab versus tocilizumab in anti-TNF inadequate responder patients with rheumatoid arthritis (R4RA). Lancet (2021)

Disclosure of Interests

None declared

POS0441 IN-DEPTH ANALYSIS OF Axl AND MerTK EXPRESSION PATTERNS AND REGULATION BY BIOLOGIC TREATMENTS IN RHEUMATOID ARTHRITIS

Background

Tyrosine kinases receptors MerTK and Axl have been implicated in the pathogenesis of several autoimmune diseases. Despite sharing significant structural homology and having common ligands, Axl and MerTK have distinct features and biological functions [1]. A growing body of evidence suggests that both Axl and MerTK play a crucial role in Rheumatoid Arthritis (RA) pathogenesis and progression and may be exploited as novel therapeutic targets [2]. However, numerous unanswered questions remain to be addressed.

Objectives:

i.To define common and distinct gene-partners of Axl/MerTK and quantify their expression in RA synovial tissue.

ii.To assess the co-expression of Axl/MerTK by synovial cells.

iii.To outline the longitudinal variation in Axl/MerTK expression upon treatment intervention.

Methods

Synovial tissue samples were collected by US-guided synovial biopsy from: i. Patients with early (<12 months) RA DMARDs/steroid-naïve [n=87]; and ii. RA patients who failed the first-line biologic with TNF-inhibitors (TNFi) before and 16 weeks after receiving either Rituximab (RTX) or Tocilizumab (TOC) [n=164] [3]. Gene expression was obtained by bulk RNAseq performed on an Illumina HiSeq2500 platform. Axl-/MerTK-modules were defined using STRING networks and the module expression determined by the mean z-score of regularized log transformed expression for all genes in the set. Axl, MerTK, CD55, CD90, CD68 protein expression was analysed by multiplex immunofluorescence staining.

Results

Using STRING network analysis, we defined an Axl- and a MerTK-module composed of 31 predicted gene-partners of either Axl or MerTK. Thirteen genes were common to both modules and included the ligands Gas6 and ProteinS, and EGFR. Conversely, eighteen genes were uniquely present in the Axl-module (e.g., PIK3-family, IGF1R, IFNAR1 and STAT3) or the MerTK-module (e.g., Galectin3 and TULP, recently discovered MerTK ligands, FCGR1A/CD64, PTPN1and MEGF10). Axl/MerTK-modules quantified in the early-arthritis treatment-naïve RNAseq dataset showed a significant negative correlation with the synovitis score (Axl r=−0.33, p=0.0032; MerTK r=-0.33, p=0.003). At protein level, CD68+macrophages of the Lining showed notable heterogeneity between patients: they could express either Axl or MerTK alone, or co-express both. Axl was also present in most CD55+ Lining Fibroblast-Like-Cells (FLS) but not by CD90+ Sublining FLS while MerTK, as expected, was restricted to macrophages, including intra-aggregate tingible-body-macrophages.

To define how Axl and MerTK vary depending on disease stage and treatment exposure, we quantified their gene expression in active RA patients inadequately responding to TNFi, prior and 16 weeks after starting second-line biologic (RTX or TOC) [3]. Differently from the early-arthritis cohort, MerTK was significantly up-regulated in synovia characterised by higher degree of tissue inflammation (lympho-myeloid > diffuse-myeloid > pauci-immune, p<0.0001) and significantly positively correlated with several cytokines’ genes such as TNF, IL-6, CCL8 and IL-10. MerTK expression was dependent on clinical response to RTX but not TOC as assessed by EULAR response (DAS28CRP, good vs none/mod, FDRresp 0.048). Conversely, Axl expression significantly increased upon IL-6 blockade by TOC independently of the clinical response (FDRtime 0.016).

Conclusion

Our data further corroborate that Axl and MerTK constitute a dynamic axis influenced by the synovial tissue inflammatory features, the disease stage, the exposure and the response to targeted treatment and the blockade of critical inflammatory pathways over time. A better understanding of the individual features of these tyrosine kinases as well as their interaction would be beneficial to define novel treatment approaches.

References

[1]Zagórska A, et al. Nat Immunol. 2014 Oct;15(10):920-8

[2]Kemble S, Croft AP. Front Immunol. 2021 Sep 3;12:715894

[3]Humby F et al. Lancet. 2021 Jan 23;397(10271):305-317

Acknowledgements

Versus Arthritis.

Disclosure of Interests

None declared.

POS0431 PDGF-BB, TNF-α, AND LT-β REGULATE FOLLICULAR DENDRITIC CELL DEVELOPMENT IN THE RHEUMATOID SYNOVIUM

Background

Follicular dendritic cells (FDCs) fundamentally contribute to the formation of synovial ectopic lymphoid-like structures in rheumatoid arthritis (RA) which is associated with poor clinical prognosis. Despite this critical role in RA pathogenesis, FDC development in the RA synovium has not been fully elucidated.

Objectives

To investigate the role of TNF-α/LT-β and PDGF-BB in the ontogeny of RA synovial FDCs and the differentiation of lymphoid and fibroid RA synovitis.

Methods

RA Synovial tissues were obtained from the Pathobiology of Early Arthritis Cohort (PEAC) of the Centre for Experimental Medicine and Rheumatology of Queen Mary University of London. RNA-Seq analysis and confocal imaging of early and late FDC differentiation markers were carried out and the stromal cell subsets were sorted by flow cytometry. The stromal cell subsets were treated with TNF-α/LT-β and/or PDGF-BB and the expression of FDC differentiation genes was assessed by qPCR. Germinal centre reactions were setup in vitro using TNF-α/LT-β activated stromal cells, and antibody production by naive human B cells stimulated with anti IgM was measured by ELISA.

Results

Our results indicate that PDGF-BB induces the FDC marker CNA.42+ on NG2+/αSMA+ type-1 pericytes, stimulates THY-1 and αSMA gene expression, and strongly correlates with fibroid synovitis using RNA-Seq analysis. On the other hand, TNF-α/LT-β downregulate PDGFR-β, THY-1, αSMA; induce CD21, FcɣRIIB expression, and significantly correlate with lymphoid synovial pathotype. Ultrastructural examination of antigen trapping on TNF-α/LT-β-activated RA synovial fibroblasts (RASFs) showed periodically retained surface antigens and these fibroblasts were able to induce T cell independent B cell activation in in vitro germinal centre reactions. The transition from an early PDGFR-β+ pre FDCs to a late TNF-α/LT-β-responsive mature FDCs is promoted by PDGF-BB. PDGF-BB induces TNF-αR expression in RASFs and facilitates B cell recruitment via pericyte CXCL13 expression and stromal cell migration.

Conclusion

To the best of our knowledge, this is the first report describing the crosstalks between PDGF-BB and TNF-α/LT-β in FDC development in the rheumatoid synovium and its association with the evolution of lymphoid and fibroid synovitis. Selective targeting of this interplay could inhibit FDC differentiation and potentially ameliorate RA in clinically severe and drug-resistant patients.

Disclosure of Interests

None declared.

OP0109 EXPRESSION QUANTITATIVE TRAIT LOCI IN EARLY TREATMENT-NAÏVE RHEUMATOID ARTHRITIS

Background

To date more than 100 genetic loci have been associated with rheumatoid arthritis (RA), particularly in the human leukocyte antigen (HLA) region. Our understanding of the functional consequences of genetic variation in RA causality, however, is limited and it has been shown that a substantial portion of complex disease risk alleles modify gene expression in a cell-specific manner [1]. The Pathobiology of Early Arthritis Cohort (PEAC) is a longitudinal study looking at treatment-naiv̈e RA patients with genotyped data as well as both synovial and blood RNA-sequenced biopsies prior to treatment with disease modifying anti-rheumatic drugs (DMARDs).

Objectives

To explore expression quantitative trait loci (eQTL) in synovium and blood within PEAC and characterise the effects of genetic variation on gene expression measured by RNA-sequencing. A further goal was to investigate the role of these variants in RA disease severity and response variables.

Methods

Genotypes were generated by Illumina Human CoreExome-24 version 1-0 array in 118 RA patients. Single nucleotide polymorphisms (SNPs) in the HLA region were imputed using HLA-TAPAS. A candidate gene study was performed on variants within the HLA region using Plink v2.0. Synovial (n=85) and blood (n=51) RNA-sequenced samples then underwent cis-eQTL analysis (loci within ±5x105Mb of the variant) based on linear regression models with the matrixeQTL R package using PEER [2] and PCA eigenvectors as covariates. Differences in eQTL between tissues were determined using a linear interaction term.

Results

The candidate gene study determined several amino acids around HLA-DRB1 acting as markers for seropositivity, which replicated findings by Raychaudhuri et. al. [3]. Using eQTL analysis, around 33,000 synovial SNPs were found with genome-wide significance (p ≤ 5x10-8) and around 29,000 in blood. This corresponded to 279 unique significant genes in synovium and 417 in blood (Figure 1). There were 100 genes common to both synovium and blood, including PSORS1C3, HLA-DRB9 and ERAP2, which have known associations with autoimmune diseases and inflammatory arthritis. Notably, 92 genes showed significantly different patterns of QTL expression between synovial tissue and blood (p ≤ 5x10-8). eQTL data also confirmed the triad of genetic variants significantly driving tissue gene expression of HLA-DPB2, while both HLA-DPB2 SNPs and HLA-DPB2 RNA-sequencing synovial expression correlated highly with erythrocyte sedimentation rate (ESR).

Figure 1.

Manhattan plots for cis-expression quantitative trait loci (eQTL) analysis performed on 85 synovial samples (top) and 51 blood samples (middle). Tissue interaction eQTL (bottom) show significant differences between tissues (p ≤ 5x10-8).

Conclusion

The high significance of genes in the HLA region in both tissues is in-keeping with the strong association between HLA and susceptibility to RA, as well as other autoimmune diseases. Most notably variants linked to HLA-DPB2 synovial expression were found to be a marker for disease severity through ESR association. Additionally, the significant differences between eQTL in blood and synovium highlight the need to explore functional consequences of genetic associations in the diseased tissue directly.

References

[1]Thalayasingam et. al. (2018). CD4+ and B lymphocyte expression quantitative traits at rheumatoid arthritis risk loci in patients with untreated early arthritis: implications for causal gene identification. Arthritis & Rheumatology, 70(3), 361-370.

[2]Stegle et al. (2012). Using probabilistic estimation of expression residuals (PEER) to obtain increased power and interpretability of gene expression analyses. Nature protocols, 7(3), 500-507.

[3]Raychaudhuri et al. (2012). Five amino acids in three HLA proteins explain most of the association between MHC and seropositive rheumatoid arthritis. Nature genetics, 44(3), 291-296.

Disclosure of Interests

None declared

Comparison of deep learning with traditional models to predict preventable acute care use and spending among heart failure patients

 

Recent health reforms have created incentives for cardiologists and accountable care organizations to participate in value-based care models for heart failure (HF). Accurate risk stratification of HF patients is critical to efficiently deploy interventions aimed at reducing preventable utilization. The goal of this paper was to compare deep learning approaches with traditional logistic regression (LR) to predict preventable utilization among HF patients. We conducted a prognostic study using data on 93,260 HF patients continuously enrolled for 2-years in a large U.S. commercial insurer to develop and validate prediction models for three outcomes of interest: preventable hospitalizations, preventable emergency department (ED) visits, and preventable costs. Patients were split into training, validation, and testing samples. Outcomes were modeled using traditional and enhanced LR and compared to gradient boosting model and deep learning models using sequential and non-sequential inputs. Evaluation metrics included precision (positive predictive value) at k, cost capture, and Area Under the Receiver operating characteristic (AUROC). Deep learning models consistently outperformed LR for all three outcomes with respect to the chosen evaluation metrics. Precision at 1% for preventable hospitalizations was 43% for deep learning compared to 30% for enhanced LR. Precision at 1% for preventable ED visits was 39% for deep learning compared to 33% for enhanced LR. For preventable cost, cost capture at 1% was 30% for sequential deep learning, compared to 18% for enhanced LR. The highest AUROCs for deep learning were 0.778, 0.681 and 0.727, respectively. These results offer a promising approach to identify patients for targeted interventions.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): internally funded by Diagnostic Robotics Inc.

63 The “Brighton Connector”: A Simple, Reproducible and Cost-Effective Technique for Bilateral Antegrade Cerebral Perfusion During Aortic Arch Surgery

Aim

Surgery of the aortic arch presents significant technical and physiological challenges. Selective antegrade cerebral perfusion (SACP) during arch surgery has been shown to improve mortality and neurological outcomes in these patients. At our centre, we aimed to develop a safe, reliable, and cost-effective technique to provide bilateral antegrade cerebral perfusion without the need of another pump head.

Method

We developed our system using equipment that is included in the accessory packaging for the Sorin Xtra cell saver system, which is readily available in cardiac surgical units nationwide, but often discarded as it is not required. An EOPA arterial return cannula and the TRUE FLOW RDB SACP cannula were joined using our novel connection.

Results

A single surgeon has used the “Brighton Connector” for 6 patients in the last two years. All patients made a satisfactory recovery with a 0% rate of mortality or permanent neurological deficit.

Conclusions

All components in our circuit are already approved for use in cardiac theatres, and the connection tubing would normally be discarded, making our method cost neutral. We demonstrate through a case series that mortality and neurological outcomes are good and comparable with other techniques.

Developing a core outcome set for community and primary care musculoskeletal services: A consensus approach

BACKGROUND

At present there is no core outcome set (COS) for use in community and primary care Musculoskeletal (MSK) services across the UK. Services are therefore collecting different MSK outcomes and metrics in different ways and at different times. Standardising MSK data collection is essential in order for fair and impactful benchmarking to improve the quality of care delivered to the millions of patients presenting each year with MSK disorders.

OBJECTIVE

To gain consensus on a proposed set of metrics that could be used to develop a COS for use in routine practice in community and primary care MSK services in the UK and to make recommendations to inform a future national MSK audit.

METHODS

A consensus process involving researchers, healthcare professionals and patients. Previous research generated an initial list of proposed metrics. This proposal was then taken to wider stakeholder consensus via an online survey designed for both healthcare professionals and MSK service users.

RESULTS

199 respondents completed the survey, 166 healthcare professionals and 33 service users (25/33 eligible to answer all items within the survey). Metrics that reached strong consensus were; age, pain site, comorbidities, duration of symptoms, work status, work absence, work absence duration. No Patient Reported Outcome Measures (PROMs) met strong consensus and all Patient Reported Experience Measures (PREMs) other than timeliness/convenience met strong consensus criteria.

CONCLUSION

7 baseline factors and 9 PREM domains reached strong consensus. The MSK-HQ PROM was the highest rated outcome measure so was also recommended for inclusion in an MSK COS.

Impact of STIMUlant and osmotic LAXatives (STIMULAX trial) on gastrointestinal recovery after colorectal surgery: randomized clinical trial

BACKGROUND

Recovery of gastrointestinal (GI) function is often delayed after colorectal surgery. Enhanced recovery protocols (ERPs) recommend routine laxative use, but evidence of benefit is unclear. This study aimed to investigate whether the addition of multimodal laxatives to an ERP improves return of GI function in patients undergoing colorectal surgery.

METHODS

This was a single-centre, parallel, open-label RCT. All adult patients undergoing elective colorectal resection or having stoma formation or reversal at the Royal Adelaide Hospital between August 2018 and May 2020 were recruited into the study. The STIMULAX group received oral Coloxyl® with senna and macrogol, with a sodium phosphate enema in addition for right-sided operations. The control group received standard ERP postoperative care. The primary outcome was GI-2, a validated composite measure defined as the interval from surgery until first passage of stool and tolerance of solid intake for 24 h in the absence of vomiting. Secondary outcomes were the incidence of prolonged postoperative ileus (POI), duration of hospital stay, and postoperative complications. The analysis was performed on an intention-to-treat basis.

RESULTS

Of a total of 170 participants, 85 were randomized to each group. Median GI-2 was 1 day shorter in the STIMULAX compared with the control group (median 2  (i.q.r. 1.5-4) versus 3 (2-5.5) days; 95 per cent c.i. -1 to 0 days; P = 0.029). The incidence of prolonged POI was lower in the STIMULAX group (22 versus 38 per cent; relative risk reduction 42 per cent; P = 0.030). There was no difference in duration of hospital day or 30-day postoperative complications (including anastomotic leak) between the STIMULAX and control groups.

CONCLUSION

Routine postoperative use of multimodal laxatives after elective colorectal surgery results in earlier recovery of gastrointestinal function and reduces the incidence of prolonged POI. Registration number: ACTRN12618001261202 (www.anzctr.org.au).

OP0136 RITUXIMAB PREVENTS THE PROGRESSION OF B-CELL DRIVEN INFLAMMATORY INFILTRATE IN THE MINOR SALIVARY GLANDS OF PRIMARY SJOGREN’S SYNDROME BY DOWNREGULATING IMMUNOLOGICAL PATHWAYS KEY IN ECTOPIC GERMINAL CENTRE ORGANIZATION: RESULTS FROM THE TRACTISS TRIAL

Background:

The pathogenic role of B-cells in primary Sjögren’s Syndrome (pSS) is well established and B cell abnormalities. Because of the substantial role of B-cells, rituximab (RTX), a chimeric anti-CD20 monoclonal antibody, has been considered as a potential biologic disease modifying drug to reduce disease activity in pSS. To date, the TRial for Anti-B-Cell Therapy In patients with pSS (TRACTISS) is the largest multi-centre, placebo-controlled trial with RTX. Despite the unmet primary endpoints (30% reduction in fatigue or oral dryness, measured by visual analogue scale), RTX treated patients showed an improvement in unstimulated whole salivary flow (Bowman et al. Arthritis Rheumatol 2017;69:1440–1450).

Objectives:

To provide the first longitudinal transcriptomic and histological analysis at 3 time points over 48 weeks of labial SGs of pSS patients treated with RTX, in comparison to placebo, from the TRACTISS cohort.

Methods:

26 pSS patients randomised to RTX or placebo arm consented for labial SG biopsies at baseline, weeks 16 and 48. Patients received two 1000mg cycles of RTX or placebo at baseline and week 24. SG focus score, inflammatory aggregate area fraction, B-cells (CD20+), T-cells (CD3+), follicular dendritic cells (FDCs) (CD21+) and plasma cells (CD138+) density were assessed by H&E and immunofluorescence staining. The histological analysis was performed by digital imaging using QuPath software. RNA was extracted from matched labial SG lobules and sequenced with Illumina platform. A Principal Component Analysis (PCA) and features driving the PCA were investigated along with the most influential gene loadings. The limma-voom R pipeline was used to extract Differential Expressed Genes (DEGs) between placebo and RTX group at week 48, and gene ontology (GO) enrichment analysis performed through EnrichR to derive GO terms and pathways associated with DEGs.

Results:

Placebo-treated labial SGs showed a worsening of inflammation highlighted by the increment of B-cell density, development of new FDC networks, and a higher ectopic GC prevalence at week 48, compared to RTX-treated patients. No difference in total T-cells and plasma cell infiltration was observed. RTX downregulated genes involved in immune cell recruitment and inflammatory aggregate organisation (e.g. CCR7, CCL19, CD52, and PDCD1) and gene signature-based analysis of 64 immune cell types highlighted how RTX preferentially blocked class-switched- and memory-B-cells infiltration in SGs at week 48. Pathway analyses confirmed the downregulation of leukocyte migration, MHC class II antigen presentation, and T-cell co-stimulation immunological pathways, such as the CD40 receptor complex pathway. The analysis of placebo SGs transcriptomic at week 48 showed a higher expression of genes linked to ectopic GC organisation, such as CXCL13, CCL19, LTβ, in female compared to male subjects. Gender was confirmed as a key co-variate responsible for most of the variation in the PCA, together with the SG focus score and the foci area fraction.

Conclusion:

Treatment with RTX showed beneficial effects on labial SG inflammatory infiltration in pSS, by downregulating genes involved in immune cell recruitment, activation and organisation in ectopic GCs. Class-switched-B-cells, memory-B-cells and FDC network development were primarily affected appearing to be responsible for the lack of progression in SG B cell infiltration in the RTX compared to the placebo arm in which clear worsening of SG immunopathology over 48 weeks was detected in female patients. Although a clear association with the clinical improvement in unstimulated salivary flow observed at week 48 in RTX-treated patients could not be established given the low number of patients consenting to 3 longitudinal biopsies it is conceivable that RTX is responsible for preserving exocrine function.

Acknowledgements:

SJB receives a salary contribution from the NIHR Birmingham Biomedical Research Centre.

Disclosure of Interests:

Elena Pontarini: None declared, Farzana Chowdhury: None declared, Elisabetta Sciacca: None declared, Sofia Grigoriadou: None declared, Felice Rivellese: None declared, Davide Lucchesi: None declared, Katriona Goldmann: None declared, Liliane Fossati-Jimack: None declared, Paul Emery: None declared, Wan Fai Ng: None declared, Nurhan Sutcliffe: None declared, Colin Everett: None declared, Catherine Fernandez: None declared, Anwar Tappuni: None declared, Myles Lewis: None declared, Costantino Pitzalis: None declared, Simon J. Bowman Consultant of: SJB In 2020 I have received consultancy fees from Novartis, Abbvie and Galapagos., Michele Bombardieri: None declared

OP0011 INTEGRATION OF FLOW AND DIGITAL CYTOMETRY IN EARLY TREATMENT-NAÏVE RHEUMATOID ARTHRITIS IDENTIFIES DISTINCT IMMUNOPHENOTYPES IN PERIPHERAL BLOOD AND DISEASE TISSUE

Background:

The study of synovial tissue in patients with Rheumatoid Arthritis (RA) has led to the identification of synovial patterns of immune cell infiltration and specific cellular subsets associated that have been disease activity and clinical outcomes(1–3). However, the relationship of circulating and synovial immune cell sub-sets with histopathological features and clinical outcomes remains to be defined.

Objectives:

To assess the relationship of peripheral blood and synovial immune cells with RA histopathology and clinical outcomes, by performing flow and digital cytometry in matched peripheral blood and synovial samples from patients with early RA.

Methods:

70 patients with early (<12 months) untreated RA (2010 criteria) recruited in the pathobiology of early Arthritis Cohort (PEAC) at the Barts Health NHS Trust were included(1). Peripheral blood mononuclear cells (n=70) were analysed by flow cytometry. Matched synovial tissues (n=70) obtained by minimally invasive ultrasound-guided synovial biopsy underwent semi-quantitative scoring (0-4) of immune cell infiltration and classification into lympho-myeloid (LM), diffuse-myeloid (DM) and pauci-immune (PI) pathotypes, as previously described(1). 49 synovial and 36 matched peripheral blood samples underwent RNA-sequencing and were analysed by digital cytometry (Xcell) (4) and Singular Value Decomposition (SVD).

Results:

Circulating B cells and their subsets showed significant inverse correlations with inflammatory markers (ESR, CRP), disease activity (swollen joints, four components and two components(5) DAS28) and ultrasound scores (Fig 1A). Among T cell subsets, CXCR5-PD1hiICOS+CD4+ T cells (T peripheral helper cells, Tph) had strong positive correlations with inflammatory markers (ESR and CRP), disease activity (DAS28) and ultrasound scores (Fig 1B). Tph in the peripheral blood also correlated with immune cell infiltration in synovia (Fig 1C) and were significantly higher in patients with a LM pathotype (Fig 1D). Accordingly, circulating Tph were associated with synovial LM pathotype independently of clinical features such as DAS28, ACPA positivity, Body Mass Index (BMI) and age (AUC 0.821). By applying digital cytometry in matched synovial and peripheral blood samples, synovial B and T cells were significantly higher in patients with a LM pathotype, in line with the histological definition of the LM pathotype – rich in B and T cells. On the contrary, circulating B cells and total CD4 and CD8 T cells were significantly lower in patients with a synovial LM pathotype (Fig 1E). The Tph signature in synovia derived by Singular Value Decomposition (SVD) correlated with baseline ESR (R 0.38, p<0.0001) and DAS28 (R 0.35, p <0.0001) and with delta-DAS28 after 6 months of treatment with conventional synthetic DMARDs (R 0.27, p 0.026). Finally, the baseline synovial Tph signature was significantly higher in patients who progressed to the use of biologics and was predictive of future biologic DMARDs use, independently of baseline DAS28, ACPA positivity, BMI and age (AUC 0.703).

Conclusion:

By combining conventional flow cytometry in the peripheral blood and digital cytometry on matched synovial and peripheral blood samples, we highlight diverging associations of circulating immune cell subsets with synovial inflammation and pathotypes. Tph cells, in particular, emerge as predictors of lympho-myeloid synovial inflammation and disease progression.

References:

[1]F. Humby et al., Ann. Rheum. Dis. 78, 761–772 (2019), doi:10.1136/annrheumdis-2018-214539. [2]M. J. Lewis et al., Cell Rep. 28, 2455-2470.e5 (2019), doi:10.1016/j.celrep.2019.07.091.[3]D. a Rao et al., Nat. Publ. Gr. 542, 110–114 (2017), doi:10.1038/nature20810.[4]D. Aran et al., Genome Biol. 18, 220 (2017), doi:10.1186/s13059-017-1349-1.[5]E. M. A. Hensor et al., Rheumatology. 58, 1400–1409 (2019), doi:10.1093/rheumatology/kez049.

Figure 1.

Acknowledgements:

The Pathobiology of Early Arthritis Cohort (PEAC) was supported by the MRC (grant 36661). Versus Arthritis provided funding infrastructure support (grant 20022). F. Rivellese is funded by an NIHR Transitional Research Fellowship (TRF-2018-11-ST2-002). We would like to thank the patients and the clinical and laboratory team (core team) at Queen Mary University of London.

Disclosure of Interests:

None declared

Determining sample size for progression criteria for pragmatic pilot RCTs: the hypothesis test strikes back!

Background

The current CONSORT guidelines for reporting pilot trials do not recommend hypothesis testing of clinical outcomes on the basis that a pilot trial is under-powered to detect such differences and this is the aim of the main trial. It states that primary evaluation should focus on descriptive analysis of feasibility/process outcomes (e.g. recruitment, adherence, treatment fidelity). Whilst the argument for not testing clinical outcomes is justifiable, the same does not necessarily apply to feasibility/process outcomes, where differences may be large and detectable with small samples. Moreover, there remains much ambiguity around sample size for pilot trials.

Methods

Many pilot trials adopt a ‘traffic light’ system for evaluating progression to the main trial determined by a set of criteria set up a priori. We construct a hypothesis testing approach for binary feasibility outcomes focused around this system that tests against being in the RED zone (unacceptable outcome) based on an expectation of being in the GREEN zone (acceptable outcome) and choose the sample size to give high power to reject being in the RED zone if the GREEN zone holds true. Pilot point estimates falling in the RED zone will be statistically non-significant and in the GREEN zone will be significant; the AMBER zone designates potentially acceptable outcome and statistical tests may be significant or non-significant.

Results

For example, in relation to treatment fidelity, if we assume the upper boundary of the RED zone is 50% and the lower boundary of the GREEN zone is 75% (designating unacceptable and acceptable treatment fidelity, respectively), the sample size required for analysis given 90% power and one-sided 5% alpha would be around n = 34 (intervention group alone). Observed treatment fidelity in the range of 0–17 participants (0–50%) will fall into the RED zone and be statistically non-significant, 18–25 (51–74%) fall into AMBER and may or may not be significant and 26–34 (75–100%) fall into GREEN and will be significant indicating acceptable fidelity.

Discussion

In general, several key process outcomes are assessed for progression to a main trial; a composite approach would require appraising the rules of progression across all these outcomes. This methodology provides a formal framework for hypothesis testing and sample size indication around process outcome evaluation for pilot RCTs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40814-021-00770-x.

Onabotulinum toxin-A versus extended release tolterodine in the management of idiopathic overactive bladder in children: A pilot randomised controlled trial (OVERT trial)

BACKGROUND

Idiopathic Overactive Bladder is the most common cause of urinary incontinence in children. Anticholinergic medications are successful in only 20% of those with daily wetting so there is a real need to find a more effective treatment for this condition. Onabotulinum toxin A injections are often used as a treatment but there have been no randomised controlled trials investigating effectiveness in children.

OBJECTIVE

To provide information that would inform the design and conduct of a definitive trial comparing onabotulinum toxin A with extended-release tolterodine for the management of therapy resistant idiopathic overactive bladder in children. Specific objectives were to assess rates of eligibility, recruitment, acceptability of randomisation, loss to follow-up, acceptability of urodynamic assessment and obtain primary outcome data for sample size estimation.

STUDY DESIGN

Single-centre, parallel, two-arm, open-label pilot randomised controlled trial. Eligible patients (aged 7-16 years) were recruited at Royal Manchester Children's Hospital and randomised (1:1) using a web-based system.

TRIAL REGISTRATION

EudraCT 2014-001068-36; Funding: UK NIHR Research for Patient Benefit Programme.

RESULTS

98 patients were assessed for eligibility, 85 (87%) were eligible for screening, parents of 62 (73%) provided consent, 46 (74%) remained eligible and were randomised (onabotulinum = 22, tolterodine = 24). All participants commenced allocated treatment. Two patients withdrew from follow-up. All participants underwent urodynamic assessment at baseline and 35 (76%) additionally at week 6. The mean (standard deviation) number of wetting episodes per day at week 6 was 1.4 (1.7) in the onabotulinum group and 1.6 (1.0) in the tolterodine group. There was one serious adverse event (probably related to the drug) and 22 non-serious adverse events reported by 8 participants in the onabotulinum group (36%). There were 23 non-serious adverse events reported by 9 participants in the tolterodine group (38%).

DISCUSSION

Recruitment was challenging but eligibility and consent rates were high as were retention rates. Treatment compliance in the botox group was high but it was difficult to measure in the tolterodine group. Treatment switching was also an issue.

CONCLUSIONS

Recruitment to a definitive trial was demonstrated to be feasible if a large number of centres are involved, though further consideration is required regarding trial design.

THU0082 MERTK SYNOVIAL EXPRESSION CORRELATES WITH TREATMENT RESPONSE IN RHEUMATOID ARTHRITIS

Background:

Despite substantial improvements in long-term clinical outcomes, a significant proportion of rheumatoid arthritis (RA) patients still fail to respond to treatment adequately, and early prognostic biomarkers of response are missing. Single-cell transcriptomic studies on RA synovial tissue (ST) have shown that MerTK is highly expressed in “anti-inflammatory” macrophages [1]. It has also been suggested that synovial macrophages isolated from RA patients in remission are characterised by a CD206+/MerTK+ signature [2]. Finally, monocyte-derived macrophages from RA patients treated with TNF-inhibitors (TNF-i) up-regulate MerTK.

Objectives:

To assess i) the modulation of synovial tissue MerTK+ macrophages upon treatment with conventional synthetic (cs) disease-modifying anti-rheumatic drugs (DMARDs) and ii) the relationship between baselineMerTKgene expression and response to TNFi.

Methods:

ST was obtained by US-guided synovial biopsies of an inflamed peripheral joint in patients with early (<12 months) treatment-naïve RA (as per ACR/EULAR 2010 criteria). A second biopsy of the same joint was repeated six months after starting treatment with single or multiple csDMARDs. ST (n=15) was stained for CD68, MerTK and CD206 by immunofluorescence using a tyramide amplification signal system. Quantification of the percentage of single- (MerTK+ or CD206+) and double-positive (CD206+MerTK+) CD68+ macrophages was obtained by digital image analysis (Image J). Gene expression analysis was performed on RNA sequences of 22 baseline ST samples (treatment-naïve).

Results:

Before any treatment intervention, the percentage of MerTK+CD206+ macrophages was significantly higher in RA patients with low (DAS28<3.2) versus high (DAS28>5.1) disease activity (24.5±20.1 versus 4.8±4.8, p<0.05). There were no differences in the relative number of MerTK+ or CD206+ or MerTK+CD206+ macrophages at baseline in relationship with the clinical response to csDMARDs at 6-months. On the other hand, patients (n=5) achieving remission (DAS<2.6) upon receiving csDMARDs significantly increased the number of MerTK+ macrophages from pre- to six-months post-treatment (23.6±23.8 to 55.5±15.4, p<0.05) in comparison with patients (n=5) who were still active after treatment (18±15.6 to 30.4±11.17, p=ns). MerTK synovial gene expression at baseline (i.e., in newly diagnosed treatment-naïve RA patients) was significantly higher in patients subsequently treated with TNFi and achieving a good/moderate EULAR response at 12 months in comparison with those who did not respond (n=14, n=8, p adjusted 0.003).

Conclusion:

Our whole-tissue protein expression data further support the hypothesis that a selective expansion of the MerTK+ macrophage subset characterise patients achieving remission. Moreover, the pre-treatment up-regulation of the MerTK gene in future responders to TNFi suggest that MerTK is implicated in modulating synovial inflammatory responses and may be exploited as a therapeutic target in RA.

References:

[1]F. Zhang et al, Nature Immunology, vol. 20, no. 7, pp. 928–942, 2019.

[2]S. R. Finlay at al, Annals of the Rheumatic Diseases, vol. 77, Supplement 2, pp. 183–183, 2018.

[3]Y. Degboé et al, Frontiers in Immunology, vol. 10, p. 3, 2019.

Acknowledgments:

Versus Arthritis

Disclosure of Interests:

None declared

OP0217 INVOLVEMENT OF LARGE JOINTS AT DISEASE PRESENTATION IS ASSOCIATED WITH DIVERSE HISTOPATHOLOGICAL FEATURES AND CLINICAL OUTCOMES IN EARLY RHEUMATOID ARTHRITIS

Background:

The involvement of large joints at disease presentation in early Rheumatoid Arthritis (RA) has been associated with severe disease activity. At the same time, the clinical heterogeneity of RA is known to be mirrored by heterogeneity of synovial inflammation, with specific histological patterns (pathotypes) associated with treatment response and disease progression. However, it is not known whether joint size is associated with specific pathotypes.

Objectives:

To analyse histopathological features of synovial biopsies from joints of different sizes and establish the relationship with clinical outcomes in patients with early RA.

Methods:

167 patients with early (<1 year) treatment-naïve RA, fulfilling the 2010 RA criteria and recruited at Barts Health NHS Trust, underwent US-guided synovial biopsy of the most inflamed joint, either large (knee), medium (e.g. wrist, ankle, elbow) or small (MCPs, MTPs), before starting treatment with csDMARDS with a treat to target approach. Upon SQ scoring (0-4) of immune cell infiltration, tissues were classified into lympho-myeloid, diffuse-myeloid and pauci-immune pathotypes. Synovial samples from 111 patients underwent RNA-seq.

Results:

The majority of synovial biopsies were performed on medium and small joints (60.6% and 19.4%) as compared to 21.3% in large joints (Table 1). At baseline, patients who underwent large joint biopsy showed significantly higher levels of inflammation (CRP 27.9±32.4 large, 20.7±26.9 medium, 10.4±9.8 small, p=0.007) and higher HAQ (1.8 ± 0.7 large, 1.4 ± 0.8 medium, 1.2 ±0.9 small, p=0.012), with no differences in DAS28. Significantly higher inflammatory scores and higher proportion of lympho-myeloid pathotype were observed in large joints (Table 1 and Figure 1). 6 months after treat-to-target treatment with csDMARDs, large joints patients had significantly higher HAQ and lower response (RR for low disease activity in large vs medium joints 0.5, 95%CI 0.2-0.9, p=0.03). Finally, differentially expressed genes by RNA-seq showed segregation according to joint size (Figure 2), with upregulation of genes of the Homeobox transcription factors family in large joints.

Table 1.

EULAR 2010 RA (n=167)

Large joints#33 (19.4%)Medium joints#100 (60.6%)Small Joints#34 (20%)P*Clinical featuresESR mm/h,mean (SD)48.2 (31.5)39.6 (30.8)29.2 (17.3)nsCRP mg/L,mean (SD)27.9 (32.4)20.7 (26.9)10.4 (9.8)0.007DAS28, mean (SD)6 (1.2)5.7 (1.4)5.7 (1.5)nsHAQ, mean (SD)1.8 (0.7)1.4 (0.8)1.2 (0.9)0.012ACPA-positive, %70.9%77.3%83.9%nsRF-positive,%71.9%74.2%80.6%nsHistologyInflammatory score,median IQR)5 (3)4 (4)2 (2.75)<0.001Pathotype,%Ungraded6.1%7.8%2.9%0.014Fibroid6.1%24.3%32.3%Myeloid30.3%28.1%47.1%Lympho-myeloid57.6%39.8%17.6%Clinical outcomes at 6 monthsDAS28 6m,mean (SD)4.2 (1.8)3.4 (1.9)3.7 (1.5)nsHAQ 6m,mean (SD)1.2 (0.8)0.8 (0.8)0.8 (0.8)0.012DAS28 6m <3.2,%23.3%48.8%37.9%0.04

#Large joints: knees; Medium joints: wrists, ankle, elbows; Small joints: MCPs, MTPs, PIPs; * Chi-squared or Kruskal–Wallis as appropriate;

Conclusion:

Synovial biopsy of large joints as the most inflamed joints at disease presentation identified patients with early RA with specific histopathological features and clinical outcomes. Together with clustering of differentially expressed genes according to joint size, this suggests that the involvement of different joint compartments in early RA contributes to disease heterogeneity with potential physiopathological and clinical implications.

References:

[1]Humby et al Ann Rheum Dis. 2019 Jun;78(6):761-772

[2]Lewis et al Cell Rep. 2019 Aug 27;28(9):2455-2470.e5

[3]Linn-Rasker SP et al Ann Rheum Dis. 2007 May;66(5):646-50

Acknowledgments:

PEAChttp://www.peac-mrc.mds.qmul.ac.ukMRC grant 36661 & ARUK Grant 20022

F. Rivellese NIHR Fellowship TRF-2018-11-ST2-002

Disclosure of Interests:

None declared

Impulsivity, personality and bipolar disorder

Background

Increased impulsivity is a diagnostic feature of mania in bipolar disorder (BD). However it is unclear whether increased impulsivity is also a trait feature of BD and therefore present in remission. Trait impulsivity can also be construed as a personality dimension but the relationship between personality and impulsivity in BD has not been explored. The aim of this study was to examine the relationship of impulsivity to clinical status and personality characteristics in patients with BD.

Methods

We measured impulsivity using the Barratt Impulsiveness Scale (BIS-11) and personality dimensions using Eysenck Personality Questionnaire in 106 BD patients and demographically matched healthy volunteers. Clinical symptoms were assessed in all participants using the Clinical Global Impressions Scale, the Montgomery-Asberg Depression Rating Scale and the Young Mania Rating Scale. Based on their clinical status patients were divided in remitted (n = 36), subsyndromal (n = 25) and syndromal (n = 45).

Results

There was no difference in BIS-11 and EPQ scores between remitted patients and healthy subjects. Impulsivity, Neuroticism and Psychoticism scores were increased in subsyndromal and syndromal patients. Within the BD group, total BIS-11 score was predicted mainly by symptoms severity followed by Psychoticism and Neuroticism scores.

Conclusions

Increased impulsivity may not be a trait feature of BD. Symptom severity is the most significant determinant of impulsivity measures even in subsyndromal patients.

The relationship of impulsivity to response inhibition and decision-making in remitted patients with bipolar disorder

Background

Impulsivity, a core feature of bipolar disorder (BD), is a multifaceted concept encompassing failure of response inhibition and poor decision-making. Abnormalities in these two cognitive domains have been reported in BD patients but their relationship with impulsivity has not been explored.

Methods

Twenty-five remitted patients with BD completed the Barratt Impulsiveness Scale (BIS) and performed the Hayling Sentence Completion Task (HSCT) and a computerized version of the Iowa Gambling task. The HSCT total errors scaled score was used as a measure of response inhibition while the gabling task score, which reflects participants' ability to make advantageous choices, was used a measure of decision making.

Results

Higher scores on the BIS attentional and non-planning subscales were respectively associated with more errors in the HSCT and less advantageous choices in the gambling task.

Limitations

All patients were medicated. Healthy participants were not included.

Conclusions

Viewed in the context of recent relevant studies our findings suggest that impulsivity, response inhibition and decision-making in BD may represent behavioural manifestations of the same underlying biological mechanism possibly linked to ventral prefrontal cortical function.

Stratified primary care versus non-stratified care for musculoskeletal pain: findings from the STarT MSK feasibility and pilot cluster randomized controlled trial

BACKGROUND

Musculoskeletal (MSK) pain from the five most common presentations to primary care (back, neck, shoulder, knee or multi-site pain), where the majority of patients are managed, is a costly global health challenge. At present, first-line decision-making is based on clinical reasoning and stratified models of care have only been tested in patients with low back pain. We therefore, examined the feasibility of; a) a future definitive cluster randomised controlled trial (RCT), and b) General Practitioners (GPs) providing stratified care at the point-of-consultation for these five most common MSK pain presentations.

METHODS

The design was a pragmatic pilot, two parallel-arm (stratified versus non-stratified care), cluster RCT and the setting was 8 UK GP practices (4 intervention, 4 control) with randomisation (stratified by practice size) and blinding of trial statistician and outcome data-collectors. Participants were adult consulters with MSK pain without indicators of serious pathologies, urgent medical needs, or vulnerabilities. Potential participant records were tagged and individuals sent postal invitations using a GP point-of-consultation electronic medical record (EMR) template. The intervention was supported by the EMR template housing the Keele STarT MSK Tool (to stratify into low, medium and high-risk prognostic subgroups of persistent pain and disability) and recommended matched treatment options. Feasibility outcomes included exploration of recruitment and follow-up rates, selection bias, and GP intervention fidelity. To capture recommended outcomes including pain and function, participants completed an initial questionnaire, brief monthly questionnaire (postal or SMS), and 6-month follow-up questionnaire. An anonymised EMR audit described GP decision-making.

RESULTS

GPs screened 3063 patients (intervention = 1591, control = 1472), completed the EMR template with 1237 eligible patients (intervention = 513, control = 724) and 524 participants (42%) consented to data collection (intervention = 231, control = 293). Recruitment took 28 weeks (target 12 weeks) with > 90% follow-up retention (target > 75%). We detected no selection bias of concern and no harms identified. GP stratification tool fidelity failed to achieve a-priori success criteria, whilst fidelity to the matched treatments achieved "complete success".

CONCLUSIONS

A future definitive cluster RCT of stratified care for MSK pain is feasible and is underway, following key amendments including a clinician-completed version of the stratification tool and refinements to recommended matched treatments.

TRIAL REGISTRATION

Name of the registry: ISRCTN.

TRIAL REGISTRATION NUMBER

15366334. Date of registration: 06/04/2016.

Efficacy of electromotive drug administration in delivering botulinum toxin a in children with neuropathic detrusor overactivity-outcomes of a pilot study

BACKGROUND

Intravesical botulinum toxin A (BtA) injection is well established in managing paediatric neuropathic detrusor overactivity (NDO). Electromotive drug administration (EMDA) is a less invasive method, which can be performed in the clinic, using pulsed electrical current for drug delivery via a urethral catheter. Few small studies report good outcomes following BtA via EMDA (BtA/EMDA) into bladders of children with NDO.

OBJECTIVE

The objective of this study is to assess the efficacy of BtA/EMDA in children with NDO, reduced bladder capacity and compliance.

METHODS

Twelve children with NDO on baseline urodynamic study were prospectively included. Pre-BtA/EMDA and post-BtA/EMDA results compared the following four parameters: maximal cystometric capacity, bladder compliance, maximal detrusor pressure (pDetmax) during detrusor overactivity and pDetmax at capacity. The Wilcoxon matched-pairs signed-rank test using Graphpad Prism 8 was used for analysis. Secondary outcomes include adverse effects and symptomatic improvement.

RESULTS

Fourteen episodes of BtA/EMDA were performed. Five patients received 3.3 IU/kg of Botox®, and five received 10 IU/kg (maximum 300 IU). Four patients received 10 IU/kg of Dysport®. Two patients in the Dysport®/EMDA group also received Botox®/EMDA more than six months previously. Thirteen of 14 post-EMDA results were completed and included in the paired analysis. No statistically significant improvements in any cystometric parameters were demonstrated. Eight patients subsequently had intravesical BtA injections with significant improvements in both cystometric parameters and symptoms. Two patients subsequently transitioned to adult services; one was commenced on mirabegron, and one has undergone ileocystoplasty with Mitrofanoff appendicovesicostomy.

DISCUSSION

Despite some evidence to support BtA/EMDA in children with NDO, the authors were unable to replicate previously published positive cystometric and symptomatic outcomes. In addition, BtA/EMDA performed poorly when compared with conventional intravesical BtA injections. This implies failure of EMDA to deliver BtA correctly to the target tissue. The large size of the BtA molecule or the abnormal bladder wall in NDO could account for the negative results. Thorough preparation and consultation was undertaken before this study with BtA/EMDA, and it is discouraging that the authors were unable to reproduce the positive results of other groups.

CONCLUSIONS

Although safe and acceptable to most patients, the authors cannot recommend the use of BtA/EMDA for NDO in children at present.

Neurophysiological correlates of stereotypic behaviour in a model carnivore species

Stereotypic behaviour (SB) is common in animals housed in farm, zoo or laboratory conditions, including captive Carnivora (e.g. wild ursids and felids). Neurobiological data on housing-induced SBs come from four species (macaques, two rodent species, and horses), and suggest basal ganglia (BG) dysfunction. We investigated whether similar patterns occur in Carnivora via a model, American mink, because their SB is distinctive in form and timing. We raised 32 males in non-enriched (NE) or enriched (E) cages for 2 years, and assessed two forms of SB: 1) Carnivora-typical locomotor-and-whole-body ('loco') SBs (e.g. pacing, weaving); 2) scrabbling with the forepaws. Neuronal activity was analysed via cytochrome oxidase (CO) staining of the dorsal striatum (caudate; putamen), globus pallidus (externus, GPe; internus, GPi), STN, and nucleus accumbens (NAc); and the GPe:GPi ratio (GPr) calculated to assess relative activation of direct and indirect pathways. NE mink stereotyped more, and had lower GPr CO-staining indicating relatively lower indirect pathway activation. However, no single BG area was affected by housing and nor did GPr values covary with SB. Independent of housing, elevated NAc CO-staining predicted more loco SB, while scrabbling, probably because it negatively correlated with loco SB, negatively covaried with NAc CO-staining in NE subjects. These results thus implicate the NAc in individual differences in mink SB. However, because they cannot explain why NE subjects showed more SB, they provide limited support for the BG dysfunction hypothesis for this species' housing-induced SB. More research is therefore needed to understand how barren housing causes SB in captive Carnivora.

Detecting autoreactive B cells in the peripheral blood of people with type 1 diabetes using ELISpot

Type 1 diabetes mellitus (T1D) is an autoimmune disorder where T lymphocytes damage the islet beta cells but B lymphocytes also play an important role. Although changes in peripheral B cell phenotype have been observed, little is known about the B cells that secrete the autoantibodies. We developed a sensitive B cell enzyme-linked immunospot assay (ELISpot assay) to detect individual B cell antibody responses to glutamic acid decarboxylase (GAD) and islet antigen-2 (IA-2). We found that even healthy donors have B cells that secrete antibodies in response to GAD and IA-2 in the ELISpot. There was increased B cell reactivity to autoantigens in the peripheral blood of individuals with newly-diagnosed, but not long-standing, type 1 diabetes. However, no correlation with serum autoantibody levels was found, indicating that additional factors such as antigen affinity or exposure to antigens in vivo are required for antibody secretion, and that even healthy donors have potentially autoreactive B cells.

Impacting on factors promoting intra-group aggression in secure psychiatric settings

Three preliminary and linked studies investigate the impact of making alterations to factors considered relevant to engaging in and experiencing intra-group aggression (bullying) among adult male patients detained in a single secure forensic hospital. Study one (n = 44) outlines the institutional factors, attitudes towards bullying and environmental factors that increase the likelihood of engaging in bullying and/or being victimised. Study two (n = 53 patients and 167 staff) assesses the effect of three variations of intervention that aimed to reduce intra-group aggression through direct alteration of the physical and psychosocial environment, using data from both patients and staff. Study three (n = 414) looks at the effects of two variations of the intervention used in study two, which offered patients’ participation in individual and communal activities. It was predicted that changes to the physical and social environment would produce a reduction in the factors shown to predict intra-group aggression. Attitudes supportive of bullying and the presence of social hierarchies each increased the likelihood of engaging in bullying. Indirect changes to the social environment on the wards had more positive effects than those incorporating direct alterations to the physical and social environment. The differences in effectiveness of the two approaches are discussed in relation to the established predictors of intra-group aggression. The research concludes by noting the preliminary nature of the research and outlining potential directions for future research and intervention.

Onabotulinum toxin A in children with refractory idiopathic overactive bladder: medium-term outcomes

INTRODUCTION

Botulinum toxin-A (BtA) has been used for refractory idiopathic overactive bladder (IOAB) in children. Data on the optimum dose success rates, duration of effect, complications and medium-term outcomes are limited. This study aims to analyse the authors' experience to provide medium-term results of BtA in symptomatic refractory patients.

MATERIALS AND METHODS

Patients with refractory IOAB who were treated with BtA (Botox®) were retrospectively analysed. All patients had urodynamic study before treating with BtA. Group A had low-dose BtA (LDBtA) at 5 units/kg (maximum 150 units), and Group B had high-dose BtA (HDBtA) at 10 units/kg (maximum 300 Units). Post-BtA clinical response, functional bladder capacity (FBC) and postvoid residual (PVR) were assessed in addition to the duration of response.

RESULTS

Thirty-nine patients, 11 male and 28 female, were analysed. Forty-six percentage had symptom improvement (73% of males and 36% of females [P = 0.072, ns]). The difference in response rates between LDBtA and HDBtA was not statistically significant (P = 0.684). Increase in total bladder capacity (TBC) was greater in those given HDBtA (P ≤ 0.001), but the increase in FBC was not different between the groups, due to greater PVRs in the HDBtA group. Nine patients (23%) developed UTI; however, six of these patients suffered with UTI pre-BtA as well. Only three were asymptomatic after a single treatment with BtA. The remainder required further BtA or oral anticholinergic therapy. At a median follow-up of 35.4 months (interquartile range [IQR] 25.2-46.6), 12 (31%) were asymptomatic and off all therapy, 18 (46%) were still symptomatic despite therapy and 9 (23%) had their symptoms controlled on continuing treatment.

DISCUSSION AND CONCLUSIONS

Botulinum toxin-A improves symptoms in 46% of children after the first injection in refractory IOAB. Although HDBtA resulted in greater increase in bladder capacity, it conferred no advantage in terms of success rate or duration of response. Five units/kg may be an optimum dose to use as a first treatment with the understanding that some patients will require a higher dose. And, there will be a cohort of patients who need a dose lower than 5 units/kg. A higher dose is more likely to lead to PVR leading to urine stasis and UTIs. The success of BtA only lasts until its effect wears off, and the majority of this cohort (36/39) required continuing treatment with repeat BtA or anticholinergic agents. However, it remains a useful option in patients who are intolerant or unresponsive to anticholinergic medication with symptomatic resolution in 30% at medium-term follow-up.

Individually Specified Drug Immunoconjugates in Cancer Treatment

Forty-three patients with disseminated refractory malignancies each received an individually-specified combination of either Adriamycin (24 patients) or mitomycin-C (19 patients) conjugated murine monoclonal antibodies. Tumors were typed using a panel of antibodies with both immunohistochemistry and flow cytometry. Cocktails of up to six antibodies were selected based on binding greater than 80% of the malignant cells in the biopsy specimen. These monoclonal antibody cocktails were drug conjugated and administered intravenously.

Seventeen out of twenty-four patients had reactions to the administration of Adriamycin immunoconjugates, but these were tolerable in all but two patients. Fever, chills, pruritis and skin rash were by far the most common transitory reactions. All were well controlled with premedication. In several patients it was demonstrated that there was limited antigenic drift among various biopsies within the same patient over time. Up to 1 gram of Adriamycin and up to 5 grams of monoclonal antibody were administered. The limiting factor appeared to be a variable dissociation of active Adriamycin from the antibody which unpredictably caused hemopoietic depression.

Similar findings were noted in 19 patients with mitomycin-C conjugates. Thrombocytopenia at a 60mg dose of mitomycin-C in this schedule was dose limiting. Preliminary serological evidence suggests that the development of an IgM antibody which is specific against the mouse monoclonal antibody has the specificity and sensitivity to predict clinical reactions. These antibodies were quantitatively less in mitomycin-C patients.

Selected patients were re-treated. One patient with chronic lymphocytic leukemia had re-treatment on three occasions and demonstrated regression of peripheral lymph nodes. Two patients with breast carcinoma had definite improvement in ulcerating skin lesions and two patients with tongue carcinoma had shrinkage of their lesions. No responses were seen with mitomycin-C conjugates but binding was noted to tumors and colon with likely drug induced colitis seen after colon binding. This study demonstrates the feasibility and illustrates technical considerations in preparing drug immunoconjugate cocktails for patients with refractory malignancies.

Cocktail formulation and antibody delivery was accomplished. The major technical hurdle appears to be the selection of effective conjugation methods that can be used to optimally bind drugs to monoclonal antibodies for targeted cancer therapy.

The feasibility and acceptability of a physical activity intervention for older people with chronic musculoskeletal pain: The iPOPP pilot trial protocol

INTRODUCTION

This pilot trial will inform the design and methods of a future full-scale randomized controlled trial (RCT) and examine the feasibility, acceptability and fidelity of the Increasing Physical activity in Older People with chronic Pain (iPOPP) intervention, a healthcare assistant (HCA)-supported intervention to promote walking in older adults with chronic musculoskeletal pain in a primary care setting.

METHODS AND ANALYSIS

The iPOPP study is an individually randomized, multicentre, three-parallel-arm pilot RCT. A total of 150 participants aged ≥65 years with chronic pain in one or more index sites will be recruited and randomized using random permuted blocks, stratified by general practice, to: (i) usual care plus written information; (ii) pedometer plus usual care and written information; or (iii) the iPOPP intervention. A theoretically informed mixed-methods approach will be employed using semi-structured interviews, audio recordings of the HCA consultations, self-reported questionnaires, case report forms and objective physical activity data collection (accelerometry). Follow-up will be conducted 12 weeks post-randomization. Collection of the quantitative data and statistical analysis will be performed blinded to treatment allocation, and analysis will be exploratory to inform the design and methods of a future RCT. Analysis of the HCA consultation recordings will focus on the use of a checklist to determine the fidelity of the iPOPP intervention delivery, and the interview data will be analysed using a constant comparison approach in order to generate conceptual themes focused around the acceptability and feasibility of the trial, and then mapped to the Theoretical Domains Framework to understand barriers and facilitators to behaviour change. A triangulation protocol will be used to integrate quantitative and qualitative data and findings.

Applying quantitative bias analysis to estimate the plausible effects of selection bias in a cluster randomised controlled trial: secondary analysis of the Primary care Osteoarthritis Screening Trial (POST)

Background

Selection bias is a concern when designing cluster randomised controlled trials (c-RCT). Despite addressing potential issues at the design stage, bias cannot always be eradicated from a trial design. The application of bias analysis presents an important step forward in evaluating whether trial findings are credible. The aim of this paper is to give an example of the technique to quantify potential selection bias in c-RCTs.

Methods

This analysis uses data from the Primary care Osteoarthritis Screening Trial (POST). The primary aim of this trial was to test whether screening for anxiety and depression, and providing appropriate care for patients consulting their GP with osteoarthritis would improve clinical outcomes. Quantitative bias analysis is a seldom-used technique that can quantify types of bias present in studies. Due to lack of information on the selection probability, probabilistic bias analysis with a range of triangular distributions was also used, applied at all three follow-up time points; 3, 6, and 12 months post consultation. A simple bias analysis was also applied to the study.

Results

Worse pain outcomes were observed among intervention participants than control participants (crude odds ratio at 3, 6, and 12 months: 1.30 (95% CI 1.01, 1.67), 1.39 (1.07, 1.80), and 1.17 (95% CI 0.90, 1.53), respectively). Probabilistic bias analysis suggested that the observed effect became statistically non-significant if the selection probability ratio was between 1.2 and 1.4. Selection probability ratios of > 1.8 were needed to mask a statistically significant benefit of the intervention.

Conclusions

The use of probabilistic bias analysis in this c-RCT suggested that worse outcomes observed in the intervention arm could plausibly be attributed to selection bias. A very large degree of selection of bias was needed to mask a beneficial effect of intervention making this interpretation less plausible.