AB1584-PARE UNDERSTANDING HETEROGENEITY IN PATIENTS’ CONCEPTUALIZATION OF TREATMENT FOR RHEUMATOID ARTHRITIS: A CLUSTER ANALYSIS

Background

Uptake of treat to target strategies for the management of rheumatoid arthritis (RA) is low. System-related barriers to accessing treatment are known, but poor adherence to starting and continuing treatment are prevalent causes of suboptimal care.

Objectives

To better understand heterogeneity in patients’ conceptualization of RA treatment to inform interventions aimed at improving appropriate utilization of disease modifying antirheumatic drugs (DMARDs).

Methods

Participants (pts) were recruited from the ArthritisPower US online research registry. Pts who met eligibility criteria [physician diagnosed RA currently being treated with DMARD(s)] rated 56 items (coded on 5-point scales) reflecting concepts raised during in-depth patient interviews. To combine similar items for ease of analysis and interpretation, we conducted a principal components analysis using Varimax rotation. We then entered mean scores, weighted by how heavily each item loaded onto each factor, into a k-means cluster analysis. We examined whether demographic characteristics differed across clusters using ANOVA for continuous and chi-square for categorical variables.

Results

Pts (N= 621) ranged in age from 22 to 93, with a mean of 57 years (SD= 11.5). Most (89%) were female and reported as non-Hispanic white (89%); 27% reported having a post-graduate degree. A scree plot revealed that a 4-factor solution explaining 36.8% of the variance would provide desirable interpretability, with a discontinuous drop in eigenvalues for additional factors slowly tapering and adding little discriminability between later solutions. The four factors (% variance explained, number of items) were: 1) Access to high quality care and support (12.10%, n= 21); 2) Comfortable adding/switching DMARDs (9.73%, n= 14); 3) Perceived favorable DMARD risk/benefit ratio (8.74%, n= 15); and 4) Confidence that testing reflects disease activity (6.20%, n= 6).

A 5-cluster solution showed the most stable convergence of cluster centers after 10 iterations. Figure 1 shows the weighted mean scores for each factor across clusters. The largest group (31.7%) is characterized by mean scores on each of the four factors toward the high end of mean responses for the sample, reflecting positive experiences; we labeled this group “Successfully Engaged in Care” to indicate a positive rheumatologist relationship, feeling well-informed and active participation in care. The next group (24.3%) also had high scores for Factor 1 (access to high quality care/support) and Factor 3 (perceived favorable DMARD risk/benefit ratio), but were less comfortable adding/switching DMARDs (Factor 2) and had less confidence in testing reflecting their disease activity (Factor 4); we labeled this group “Worried About Medication”.

The three remaining clusters are smaller. The third cluster (16.4%), labeled “Skeptical of Testing,” had a favorable view of DMARDs (Factor 3) despite lower scores related to access and quality of care (Factor 1) and confidence in testing (Factor 4). The fourth cluster (14.3%) expressed low perceived value of DMARDs as well as reduced scores for DMARD risk/benefit and confidence in testing; we labeled this group “Resistant to DMARDs.” The last cluster (13.2%) scored lowest on their rating of access to high quality care and support, indicating less access to, and satisfaction with, information needed to support decision making. Their perceived risk/benefit ratio for DMARDs was still favorable, so we labeled this group “Dissatisfied with Care.”

Conclusion

Patients’ conceptualization of RA treatment varies, but discomfort with adding/switching DMARDs appears to be ubiquitous regardless of perceived benefits associated with DMARDs and access to high quality care/support. Interventions outside of the traditional physician-patient relationship are needed to facilitate treatment escalation in patients with RA. Further research is required to understand residual variance not explained by our model.

Acknowledgements

The authors thank the patients for their participation.

Disclosure of Interests

Betty Hsiao: None declared, Julie Downs: None declared, Mandy Lanyon: None declared, Jeffrey R. Curtis Consultant of: Gilead, Novartis, and Samsung, Grant/research support from: AbbVie, Amgen, BMS, Corrona, Eli Lilly and Company, Janssen, Myriad, Pfizer, Regeneron, Roche, and UCB, Susan Blalock: None declared, Carole Wiedmeyer: None declared, Shilpa Venkatachalam: None declared, W. Benjamin Nowell Grant/research support from: •William B. Nowell is the Principal Investigator on grants/contracts from AbbVie, Eli Lilly and Company, and PCORI, and an employee of the Global Healthy Living Foundation (GHLF). GHLF receives grants, sponsorships and contracts from pharmaceutical manufacturers and private foundations. A full list of GHLF funders is publicly available here: https://www.ghlf.org/our-partners/., Liana Fraenkel: None declared

Aging shifts mitochondrial dynamics toward fission to promote germline stem cell loss

Changes in mitochondrial dynamics (fusion and fission) are known to occur during stem cell differentiation; however, the role of this phenomenon in tissue aging remains unclear. Here, we report that mitochondrial dynamics are shifted toward fission during aging of Drosophila ovarian germline stem cells (GSCs), and this shift contributes to aging-related GSC loss. We found that as GSCs age, mitochondrial fragmentation and expression of the mitochondrial fission regulator, Dynamin-related protein (Drp1), are both increased, while mitochondrial membrane potential is reduced. Moreover, preventing mitochondrial fusion in GSCs results in highly fragmented depolarized mitochondria, decreased BMP stemness signaling, impaired fatty acid metabolism, and GSC loss. Conversely, forcing mitochondrial elongation promotes GSC attachment to the niche. Importantly, maintenance of aging GSCs can be enhanced by suppressing Drp1 expression to prevent mitochondrial fission or treating with rapamycin, which is known to promote autophagy via TOR inhibition. Overall, our results show that mitochondrial dynamics are altered during physiological aging, affecting stem cell homeostasis via coordinated changes in stemness signaling, niche contact, and cellular metabolism. Such effects may also be highly relevant to other stem cell types and aging-induced tissue degeneration.

High incidence of false-positive PET scans in patients with aggressive non-Hodgkin's lymphoma treated with rituximab-containing regimens

BACKGROUND

Positron emission tomography (PET) is a powerful predictor of relapse and survival in non-Hodgkin's lymphomas (NHLs) based on studies carried out in the prerituximab era. Little is known about the predictive power of PET in rituximab-treated patients.

PATIENTS AND METHODS

Patients with aggressive B-cell NHL with baseline and follow-up PET studies were included. Clinical characteristics, PET and computed tomography scans, biopsy results, and outcomes were reviewed. PET was defined as positive if higher than mediastinal or background activity was observed.

RESULTS

In all, 51 patients (diffuse large B cell-38; mantle cell lymphoma-13) treated with rituximab-containing regimens were included. For 13 of 40 patients (32.5%), mid-therapy PET studies were positive and 9 of 48 patients (18.7%) had positive posttherapy PET. The positive predictive value (PPV), negative predictive value (NPV), sensitivity (Se), and specificity (Sp) of the mid-therapy PET for predicting relapse were 33% [95% confidence interval (CI) 19% to 49%], 68% (95% CI 51% to 81%), 33% (95% CI 6% to 76%), and 68% (95% CI 49% to 82%), respectively. For posttherapy PET, the relapse PPV, NPV, Se and Sp were 19% (95% CI 9% to 33%), 81% (95% CI 67% to 91%), 13% (95% CI 0.6% to 53%), and 80%(95% CI 64% to 90%), respectively.

CONCLUSIONS

Compared with previous reports in prerituximab era, addition of rituximab resulted in reduced PPV and sensitivity of mid- and posttherapy PET in patients with aggressive B-cell NHL.

Subunit-dependent modulation of neuronal nicotinic receptors by zinc

We examined the effect of zinc on rat neuronal nicotinic acetylcholine receptors (nAChRs) expressed in Xenopus oocytes as simple heteromers of alpha2, alpha3, or alpha4 and beta2 or beta4. Coapplication of zinc with low concentrations of acetylcholine (</=EC(10)) resulted in differential effects depending on receptor subunit composition. The alpha2beta2, alpha2beta4, alpha3beta4, alpha4beta2, and alpha4beta4 receptors exhibited biphasic modulation by zinc, with potentiation of the acetylcholine response occurring at 1-100 micrometer zinc and inhibition occurring at higher zinc concentrations. In contrast, alpha3beta2 receptors were only inhibited by zinc (IC(50) = 97 +/- 16 micrometer). The greatest potentiating effect of zinc was seen with alpha4beta4 receptors that were potentiated to 560 +/- 17% of the response to ACh alone, with an EC(50) of 22 +/- 4 micrometer zinc. Cadmium, but not nickel, was also able to potentiate alpha4beta4 receptors. Both zinc potentiation of alpha4beta4 receptors and zinc inhibition of alpha3beta2 receptors were voltage independent. The sensitivity of zinc potentiation of alpha4beta4 to diethylpyrocarbonate treatment and alterations in pH suggested the involvement of histidine residues. Zinc continued to inhibit alpha4beta4 and alpha3beta2 after diethylpyrocarbonate treatment. Application of a potentiating zinc concentration increased the response of alpha4beta2 and alpha4beta4 receptors to saturating ACh concentrations. The rate of Ach-induced desensitization of these receptors was unaffected by zinc. Our results reveal zinc potentiation as a new mode of neuronal nAChR modulation.

Inhibition of allergic airway responses by inhaled low-molecular-weight heparins: molecular-weight dependence

Inhaled heparin prevents antigen-induced bronchoconstriction and inhibits anti-immunoglobulin E-mediated mast cell degranulation. We hypothesized that the antiallergic action of heparin may be molecular weight dependent. Therefore, we studied the effects of three different low-molecular-weight fractions of heparin [medium-, low-, and ultralow-molecular-weight heparin (MMWH, LMWH, ULMWH, respectively)] on the antigen-induced acute bronchoconstrictor response (ABR) and airway hyperresponsiveness (AHR) in allergic sheep. Specific lung resistance was measured in 22 sheep before and after airway challenge with Ascaris suum antigen, without and after pretreatment with inhaled fractionated heparins at doses of 0.31-5.0 mg/kg. Airway responsiveness was estimated before and 2 h postantigen as the cumulative provocating dose of carbachol in breath units that increased specific lung resistance by 400%. All fractionated heparins caused a dose-dependent inhibition of ABR and AHR. ULMWH was the most effective fraction, with the inhibitory dose causing 50% protection (ID50) against ABR of 0.5 mg/kg, whereas ID50 values of LMWH and MMWH were 1.25 and 1.8 mg/kg, respectively. ULMWH was also the most effective fraction in attenuating AHR; the ID50 values for ULMWH, LMWH, and MMWH were 0.5, 2.5, and 4.7 mg/kg, respectively. These data suggest that 1) fractionated low-molecular-weight heparins attenuate antigen-induced ABR and AHR; 2) there is an inverse relationship between the antiallergic activity of heparin fractions and molecular weight; and 3) ULMWH is the most effective fraction preventing allergic bronchoconstriction and airway hyperresponsiveness.

X-ray Linear Dichroism Microscopy

Chemical-specific x-ray linear dichroism was observed in an x-ray microscope as evidenced by changes in relative contrast upon azimuthal rotation of the sample. As a demonstration, thin sections of a partially ordered polymer fiber were examined with a transmission x-ray microscope near the carbon K-shell absorption edge to provide chemical-specific imaging at 50-nanometer spatial resolution. The observed dichroism and change in contrast upon rotation arise from the polarization dependence of the near-edge x-ray absorption cross section and can be used to image the orientation of specific chemical bonds.