Evaluating site-of-care-related racial disparities in kidney graft failure using a novel federated learning framework

OBJECTIVES

Racial disparities in kidney transplant access and posttransplant outcomes exist between non-Hispanic Black (NHB) and non-Hispanic White (NHW) patients in the United States, with the site of care being a key contributor. Using multi-site data to examine the effect of site of care on racial disparities, the key challenge is the dilemma in sharing patient-level data due to regulations for protecting patients' privacy.

MATERIALS AND METHODS

We developed a federated learning framework, named dGEM-disparity (decentralized algorithm for Generalized linear mixed Effect Model for disparity quantification). Consisting of 2 modules, dGEM-disparity first provides accurately estimated common effects and calibrated hospital-specific effects by requiring only aggregated data from each center and then adopts a counterfactual modeling approach to assess whether the graft failure rates differ if NHB patients had been admitted at transplant centers in the same distribution as NHW patients were admitted.

RESULTS

Utilizing United States Renal Data System data from 39 043 adult patients across 73 transplant centers over 10 years, we found that if NHB patients had followed the distribution of NHW patients in admissions, there would be 38 fewer deaths or graft failures per 10 000 NHB patients (95% CI, 35-40) within 1 year of receiving a kidney transplant on average.

DISCUSSION

The proposed framework facilitates efficient collaborations in clinical research networks. Additionally, the framework, by using counterfactual modeling to calculate the event rate, allows us to investigate contributions to racial disparities that may occur at the level of site of care.

CONCLUSIONS

Our framework is broadly applicable to other decentralized datasets and disparities research related to differential access to care. Ultimately, our proposed framework will advance equity in human health by identifying and addressing hospital-level racial disparities.

Molecular determinants of clinical outcomes of pembrolizumab in recurrent ovarian cancer: Exploratory analysis of KEYNOTE-100

OBJECTIVE

This prespecified exploratory analysis evaluated the association of gene expression signatures, tumor mutational burden (TMB), and multiplex immunohistochemistry (mIHC) tumor microenvironment-associated cell phenotypes with clinical outcomes of pembrolizumab in advanced recurrent ovarian cancer (ROC) from the phase II KEYNOTE-100 study.

METHODS

Pembrolizumab-treated patients with evaluable RNA-sequencing (n = 317), whole exome sequencing (n = 293), or select mIHC (n = 125) data were evaluated. The association between outcomes (objective response rate [ORR], progression-free survival [PFS], and overall survival [OS]) and gene expression signatures (T-cell-inflamed gene expression profile [TcellinfGEP] and 10 non-TcellinfGEP signatures), TMB, and prespecified mIHC cell phenotype densities as continuous variables was evaluated using logistic (ORR) and Cox proportional hazards regression (PFS; OS). One-sided p-values were calculated at prespecified α = 0.05 for TcellinfGEP, TMB, and mIHC cell phenotypes and at α = 0.10 for non-TcellinfGEP signatures; all but TcellinfGEP and TMB were adjusted for multiplicity.

RESULTS

No evidence of associations between ORR and key axes of gene expression was observed. Negative associations were observed between outcomes and TcellinfGEP-adjusted glycolysis (PFS, adjusted-p = 0.019; OS, adjusted-p = 0.085) and hypoxia (PFS, adjusted-p = 0.064) signatures. TMB as a continuous variable was not associated with outcomes (p > 0.05). Positive associations were observed between densities of myeloid cell phenotypes CD11c+ and CD11c+/MHCII-/CD163-/CD68- in the tumor compartment and ORR (adjusted-p = 0.025 and 0.013, respectively).

CONCLUSIONS

This exploratory analysis in advanced ROC did not find evidence for associations between gene expression signatures and outcomes of pembrolizumab. mIHC analysis suggests CD11c+ and CD11c+/MHCII-/CD163-/CD68- phenotypes representing myeloid cell populations may be associated with improved outcomes with pembrolizumab in advanced ROC.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, NCT02674061.

DLMM as a lossless one-shot algorithm for collaborative multi-site distributed linear mixed models

Linear mixed models are commonly used in healthcare-based association analyses for analyzing multi-site data with heterogeneous site-specific random effects. Due to regulations for protecting patients’ privacy, sensitive individual patient data (IPD) typically cannot be shared across sites. We propose an algorithm for fitting distributed linear mixed models (DLMMs) without sharing IPD across sites. This algorithm achieves results identical to those achieved using pooled IPD from multiple sites (i.e., the same effect size and standard error estimates), hence demonstrating the lossless property. The algorithm requires each site to contribute minimal aggregated data in only one round of communication. We demonstrate the lossless property of the proposed DLMM algorithm by investigating the associations between demographic and clinical characteristics and length of hospital stay in COVID-19 patients using administrative claims from the UnitedHealth Group Clinical Discovery Database. We extend this association study by incorporating 120,609 COVID-19 patients from 11 collaborative data sources worldwide.

A lossless, one-shot and privacy-preserving distributed algorithm was revealed for fitting linear mixed models on multi-site data. The algorithm was applied to a study of 120,609 COVID-19 patients using only minimal aggregated data from each of 14 sites.

470 Financial and Efficacy Analysis of a Centralised Neck of Femur Fracture Service

Aim

Osteoporotic fractures are rising in incidence, costing the National Health Service up to £1.1 billion for hospital care. The implementation of the Best Practice Tariff (BPT) of fragility fractures in 2010 created a financial incentive to achieve standards of best practice. In June 2015, a dedicated hip fracture unit (HFU) was set up at Princess Royal Hospital (PRH). The aim of this study is (A) to assess changes in performance to the BPT after the introduction of a dedicated HFU, and (B) whether the performance of a HFU is affected by direct/indirect presentation to the HFU.

Method

The performance of Brighton and Sussex University Hospitals (BSUH) to BPT pre and post HFU was assessed by a retrospective review of BPT performance data between 2015 and 2016. 870 patients who were treated for NOFF at BSUH were reviewed to assess whether the performance of the HFU was impacted by patients presenting either directly (PRH) to the HFU or indirectly (presentation to Royal Sussex County Hospital). Appropriate statistical tests were used to analyse the significant differences between these outcome measures.

Results

The comparison between pre and post HFU showed there was a significant increase in the time between A&E admission to ward, theatre or orthogeriatric (OG) assessment (P < 0.001) in patients presenting indirectly to HFU compared to direct presentations.

Conclusions

Having a HFU is cost neutral, and advantages of HFU include focusing NOFF care which improves in patient care. BPT achievements could be improved by increasing the direct admission of NOFF to the HFU.

Management of peri-prosthetic joint infection and severe bone loss after total hip arthroplasty using a long-stemmed cemented custom-made articulating spacer (CUMARS)

Background

There is little evidence on techniques for management of peri-prosthetic infection (PJI) in the context of severe proximal femoral bone loss. Custom-made articulating spacers (CUMARS) utilising cemented femoral stems as spacers was described providing better bone support and longer survival compared to conventional articulating spacers. We retrospectively report our experience managing PJI by adaptation of this technique using long cemented femoral stems where bone loss precludes use of standard stems.

Methods

Patients undergoing 1st stage revision for infected primary and revision THA using a cemented long stem (> 205 mm) and standard all-polyethylene acetabulum between 2011 and 2018 were identified. After excluding other causes of revision (fractures or aseptic loosening), Twenty-one patients remained out of total 721 revisions. Medical records were assessed for demographics, initial microbiological and operative treatment, complications, eradication of infection and subsequent operations. 2nd stage revision was undertaken in the presence of pain or subsidence.

Results

Twenty-one patients underwent 1st stage revision with a cemented long femoral stem. Mean follow up was 3.9 years (range 1.7–7.2). Infection was eradicated in 15 (71.4%) patients. Two patients (9.5%) required repeat 1st stage and subsequently cleared their infection. Three patients (14.3%) had chronic infection and are on long term suppressive antibiotics. One patient (4.8%) was lost to follow up before 2 years. Complications occurred in seven patients (33%) during or after 1st stage revision. Where infection was cleared, 2nd stage revision was undertaken in 12 patients (76.5%) at average of 9 months post 1st stage. Five (23.8%) CUMARS constructs remained in-situ at an average of 3.8 years post-op (range 2.6–5.1).

Conclusions

Our technique can be used in the most taxing of reconstructive scenarios allowing mobility, local antibiotic delivery, maintenance of leg length and preserves bone and soft tissue, factors not afforded by alternative spacer options.

Does a dedicated hip fracture unit improve clinical outcomes? A five-year case series

INTRODUCTION

The aim of the study was to establish whether a dedicated hip fracture unit, geographically separate from the local major trauma centre, could improve clinical outcomes for patients sustaining proximal femoral fragility fractures.

MATERIALS AND METHODS

This study was a retrospective case series, using data collected from Brighton and Sussex University Hospitals NHS Trust's submissions to the National Hip Fracture Database between 1 April 2011 and 16 September 2016. The outcomes measured were mortality, length of hospital stay, time from admission to surgical intervention and return to premorbid residence. Patients were compared before and after reconfiguration of services into a separate dedicated hip fracture unit geographically distinct from the major trauma centre.

RESULTS

A total of 2117 patients (2178 injuries) were managed before the existence of the hip fracture unit, while 660 patients (673 injuries) were treated within the hip fracture unit. During the five-year study period, the 30-day mortality rate (pre-hip fracture unit 5.47% vs hip fracture unit 3.13%, P = 0.014), variance in the length of hospital stay (P < 0.001), mean time to surgical intervention (P = 0.044) and return to premorbid residence were significantly improved. An immediate 12-month comparison demonstrated significantly improved variance in length of hospital stay (P = 0.020) and return to premorbid residence (P = 0.015).

DISCUSSION

The reconfiguration of services significantly reduced variance in length of stay, enabling accurate resource planning in future. Multiple incremental improvements in service provision, in addition to the hip fracture unit, may explain the lower mortality observed.

CONCLUSION

While further research is required, replication of the hip fracture unit service model may potentially afford significant clinical and financial gains.

Survival analysis and functional outcome of the Oxford unicompartmental knee replacement up to 11 years follow up at a District General Hospital

BACKGROUND

There have been several large originator studies reporting excellent results with this prosthesis but far fewer large independent studies. We present, to our knowledge, the largest independent series documenting excellent survivorship rates and good functional outcomes at a mean follow up of 5.5 years post implantation of the Oxford unicompartmental knee replacement.

METHODS

Our prospective study looks at the survivorship and the functional outcome of 364 Oxford UKRs performed in a district general hospital at a mean follow up of 5.5 years (range 5-11 years). Post operatively knees were assessed in a research clinic using the Oxford knees score (as well as the American Knee Society Score and the Hospital for Special Surgery Score). Maximal flexion was also measured.

RESULTS

There were 26 revisions of 364 knees giving a survivorship, with revision as the end point, of 93% at a mean of 5.5 years post op (range 5-11 years). We achieved an Oxford score of 37.5, a mean AKSS of 161 (divided as American knee functional score 75.75/American knee objective score 85.4 (excellent)). The mean HSS score was 84.5. We achieved 'Excellent' Oxford knee scores in 137 knees (48%), 'Good' in 75 (26%), 'Moderate' in 51 (17%) and 'Poor' in only 27 (9%) of knees. Mean improvement in functional scores were: Oxford score (14.4), AKSS (71) and HSS (26.3). Mean maximal flexion was 123° range (110-140).

CONCLUSIONS

We have confirmed that good medium to long-term function and survival can be obtained following Oxford medial knee replacement for treating anteromedial osteoarthritis, in our large independent series.

Day surgery: handling patients' complaints

The number of surgical procedures being performed as day cases is increasing. In an attempt to ensure that patients are given the chance to present their views of this developing service, one unit has set up an innovative project to allow patients to voice any dissatisfactions directly to the staff. The project has led to several changes being made and increased satisfaction for both staff and patients.