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Importance: Findings from several high profile meta-analyses have raised concerns about an ongoing global decline in sperm concentration and male fertility. However, these studies exhibit considerable heterogeneity in key variables including study population, methodology, fertility status, and geographic region., Objective: To perform a systematic review and meta-analysis exploring temporal trends in sperm concentration among fertile men and men unselected for fertility status in the United States., Data Sources: A literature search performed in Scopus and PubMed databases for studies published between 1970 and 2023. Additional studies were included from citations of prior global meta-analyses and reviews evaluating temporal trends in sperm count., Study Selection and Synthesis: Studies were included if they presented original data on sperm concentration in US men without known infertility from 1970 to 2023. Aggregate data were assessed across all study populations, with additional subgroup analyses stratified by fertility status and US region., Main Outcomes: Weighted generalized linear models were generated to evaluate the association between mean sperm concentration and sample collection year., Results: A total of 874 articles were screened, with 58 meeting the inclusion criteria. These represented 75 unique study populations totaling 11,787 men in the United States. Across all study populations, no change in sperm concentration was observed between 1970 and 2018 in unadjusted models (β = 0.14 million/mL per year). When adjusting for US region, no statistically significant decline in sperm concentration was seen. When adjusting for both region and fertility status, a modest annual decline was observed to meet statistical significance (β = -0.35 million/mL per year). Of the 49 study populations reporting adequate data to determine mean total sperm count, there was a significant increase in total sperm count of 2.9 million per year between 1970 and 2018. Subgroup analysis found no statistically significant change in mean sperm concentration among any US census region or fertility status cohort., Conclusion and Relevance: In contrast to prior global studies, this analysis suggests no clinically significant decline in sperm concentration among confirmed fertile men and the general male US population without known infertility. Although these findings provide some reassurance against a widespread rapid decline, further studies are necessary to better understand this important topic., Competing Interests: Declaration of Interests K.L. has nothing to disclose. R.C. has nothing to disclose. F.L. has nothing to disclose. B.R. has nothing to disclose. L.B. has nothing to disclose. J.M. has nothing to disclose. S. Kuribayashi has nothing to disclose. S. Kuroda has nothing to disclose. D.A.P. has nothing to disclose. S.C.V. has nothing to disclose. J.C. has nothing to disclose. S.D.L. has nothing to disclose., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: The deceased donor shortage in the United States has led to increased utilization extended criteria donor (ECD) liver grafts. Centers often utilize ECD grafts in patients with low Model for End-Stage Liver Disease (MELD) scores, like patients with hepatocellular carcinoma (HCC). However, few studies have directly examined the outcomes of using ECD grafts in patients with HCC., Methods: Adults receiving liver transplantation (LT) for HCC between 2010 and 2020 were identified in the Organ Procurement and Transplantation Network database. Recipients were categorized according to donor type: standard criteria donor (SCD), extended criteria donor, donation after brain death (ECD-DBD), and donation after circulatory death (DCD). Multivariable Cox regression analysis identified variables associated with overall or graft survival at 3 years post-LT., Results: Most patients received ECD-DBD grafts (51.4%); only 8.3% received DCD grafts. The time on the waitlist was similar for ECD and SCD recipients (P = .79). SCD recipients had higher 5-year overall survival post-LT than ECD-DBD or DCD recipients (79.1%, 77.1%, and 76.8%, respectively, P < .001). Similarly, 5-year graft survival was also highest in SCD recipients (SCD = 77.8%, ECD-DBD = 75.7%, and DCD = 72.2%, P < .001). In multivariable analysis, DCD grafts increased mortality risk (hazard ratio [HR] = 1.33, 95% confidence interval [CI] = 1.12-1.57, P = .001), but ECD-DBD grafts did not (HR = 1.10, 95% CI = 1.00-1.22, P = .052)., Conclusions: DCD and ECD-DBD recipients had significantly lower overall and graft survival. However, the survival benefit of LT for patients with HCC greatly outweighs the small differences in patient and graft survival from using ECD grafts. Further research should investigate whether treatment of ECD grafts with machine perfusion may ameliorate this discrepancy., Competing Interests: Declaration of competing interest The authors have no conflicts of interest to declare for this manuscript., (Copyright © 2024 Elsevier Inc. All rights reserved.)