Use of Machine Learning Consensus Clustering to Identify Distinct Subtypes of Black Kidney Transplant Recipients and Associated Outcomes

Importance: Among kidney transplant recipients, Black patients continue to have worse graft function and reduced patient and graft survival. Better understanding of different phenotypes and subgroups of Black kidney transplant recipients may help the transplant community to identify individualized strategies to improve outcomes among these vulnerable groups. Objective: To cluster Black kidney transplant recipients in the US using an unsupervised machine learning approach. Design, Setting, and Participants: This cohort study performed consensus cluster analysis based on recipient-, donor-, and transplant-related characteristics in Black kidney transplant recipients in the US from January 1, 2015, to December 31, 2019, in the Organ Procurement and Transplantation Network/United Network for Organ Sharing database. Each cluster\u27s key characteristics were identified using the standardized mean difference, and subsequently the posttransplant outcomes were compared among the clusters. Data were analyzed from June 9 to July 17, 2021. Exposure: Machine learning consensus clustering approach. Main Outcomes and Measures: Death-censored graft failure, patient death within 3 years after kidney transplant, and allograft rejection within 1 year after kidney transplant. Results: Consensus cluster analysis was performed for 22 687 Black kidney transplant recipients (mean [SD] age, 51.4 [12.6] years; 13 635 men [60%]), and 4 distinct clusters that best represented their clinical characteristics were identified. Cluster 1 was characterized by highly sensitized recipients of deceased donor kidney retransplants; cluster 2, by recipients of living donor kidney transplants with no or short prior dialysis; cluster 3, by young recipients with hypertension and without diabetes who received young deceased donor transplants with low kidney donor profile index scores; and cluster 4, by older recipients with diabetes who received kidneys from older donors with high kidney donor profile index scores and extended criteria donors. Cluster 2 had the most favorable outcomes in terms of death-censored graft failure, patient death, and allograft rejection. Compared with cluster 2, all other clusters had a higher risk of death-censored graft failure and death. Higher risk for rejection was found in clusters 1 and 3, but not cluster 4. Conclusions and Relevance: In this cohort study using an unsupervised machine learning approach, the identification of clinically distinct clusters among Black kidney transplant recipients underscores the need for individualized care strategies to improve outcomes among vulnerable patient groups

Peripheral arterial disease and risk of hip fracture: A systematic review and meta-analysis of cohort studies

Background: Previous studies have suggested an increased risk of hip fracture among patients with peripheral arterial disease (PAD), however, the results have been inconsistent. This meta-analysis was conducted with the aim to summarize all available evidence to better characterize the risk of incident hip fracture among these patients. Materials and Methods: A comprehensive literature review was conducted using the MEDLINE and EMBASE databases through October 2017 to identify all cohort and case-control studies that compared the risk of subsequent hip fracture between patients with PAD and individuals without PAD. Effect estimates of the included studies were extracted and combined using the random-effect, generic inverse variance method of DerSimonian and Laird. Results: The systematic review process yielded six eligible cohort studies comprising 15,895 patients with PAD. There was a significant association between incident hip fracture and PAD with the pooled relative risk (RR) of 1.64 (95% CI, 1.17–2.29; I2, 80%), comparing patients with PAD and individuals without PAD. Subgroup analysis by study design revealed significant results for both prospective studies (pooled RR 1.60; 95% CI, 1.12–2.28; I2, 0%) and retrospective studies (pooled RR 1.72; 95% CI, 1.07–2.77; I2, 92%). The funnel plot is relatively asymmetric suggesting publication bias. Conclusion: This study found a significant association between PAD and hip fracture with the pooled RR of 1.64 (95% CI, 1.17–2.29) on comparing patients with PAD and individuals without PAD. Major limitations include high between-study heterogeneity, possibility of publication bias, and lack of data on the characteristics and type of hip fracture which may limit the clinical significance of the observations

Insomnia and risk of nonalcoholic fatty liver disease: A systematic review and meta-analysis

Aim: This sudy aims to investigate the association between insomnia or excessive daytime sleepiness (EDS) and risk of nonalcoholic fatty liver disease (NAFLD). Methods: We searched published studies indexed in MEDLINE and EMBASE database from inception to December 2015. Studies that reported odds ratios (ORs), risk ratios, hazard ratios or standardized incidence ratio with 95% confidence intervals (CI) comparing the risk of NAFLD among participants who had insomnia or EDS versus those without insomnia or EDS were included. Pooled ORs and 95% CI were calculated using a random-effect, generic inverse variance method of DerSimonian and Laird. Cochran's Q test and I2 statistic were used to determine the between-study heterogeneity. Results: Our search strategy yielded 2117 potentially relevant articles (781 articles from MEDLINE and 1336 articles from EMBASE). After comprehensive review, seven studies (three cross-sectional studies and four case–control studies) were found to be eligible and were included in the meta-analysis. The risk of NAFLD in participants who had insomnia was significantly higher with the pooled OR of 1.13 (95% CI, 1.00–1.27). The statistical heterogeneity was moderate with an I2 of 62%. Elevated risk of NAFLD was also observed among participants with EDS even though the 95% CI was wider and did not reach statistical significance (pooled OR 2.21; 95% CI, 0.84–5.82). The statistical heterogeneity was moderate with an I2 of 62%. Conclusions: Our study demonstrated an increased risk of NAFLD among participants who had insomnia or EDS. Whether this association is causal needs further investigations