Serum Magnesium Levels and Cardiovascular Outcomes in Systolic Blood Pressure Intervention Trial Participants.

Rationale and Objective: Serum magnesium levels have been inversely yet inconsistently associated with cardiovascular (CV) outcomes. In this study, we examined the association of serum magnesium levels with CV outcomes in the Systolic Blood Pressure Intervention Trial (SPRINT) participants. Study Design: Case-control post hoc analysis of SPRINT. Setting & Participants: A total of 2,040 SPRINT participants with available serum samples at baseline level were included in this study. Case participants (n = 510) who experienced a CV event during the SPRINT observation period (median follow-up of 3.2 years) and control participants (n = 1,530) without CV events were sampled in a 1:3 ratio for measurements of serum magnesium level at baseline and 2-year follow-up. Predictors: Baseline serum magnesium levels and 2-year percentage change in serum magnesium levels (ΔSMg). Outcome: SPRINT primary composite CV outcome. Analytical Approach: Multivariable conditional logistic regression analysis, accounting for matching factors, was used to evaluate the association of baseline and ΔSMg with CV outcomes. Individual matching of cases and controls was based on the SPRINT treatment arm allocation (standard vs intensive) and prevalence of chronic kidney disease (CKD). Results: The median serum magnesium level at baseline was similar among the case and control groups. In a fully adjusted model, each standard deviation (SD) (0.18 mg/dL) higher of the baseline serum magnesium level was independently associated with a lower risk for composite CV outcomes in all study participants (adjusted odds ratio 95% CI, 0.79 [0.70-0.89]). This association was similar when serum magnesium levels were analyzed in quartiles but dissipated in the standard (vs intensive) arm of SPRINT (0.88 [0.76-1.02] vs 0.65 [0.53-0.79], respectively; Pinteraction = 0.06). The presence or absence of CKD at baseline did not modify this association. ΔSMg was not independently associated with CV outcomes occurring after 2 years. Limitations: ΔSMg was small in magnitude, limiting effect size. Conclusions: Higher baseline serum magnesium levels were independently associated with reduced risk for CV outcomes in all study participants, but ΔSMg was not associated with CV outcomes.

Physician and Hospital-level Variation in Hemostatic Agent Use in Benign Gynecologic Procedures.

STUDY OBJECTIVE: To identify recent nationwide trends in hemostatic agent (HA) use and to explore factors associated with HA use in 3 benign gynecologic surgery contexts: isolated hysterectomy, pelvic organ prolapse repair, and anti-incontinence surgery. DESIGN: Retrospective cohort study. SETTING: Vizient Clinical Database. PATIENTS: Three cohorts of female patients of ≥18 years who underwent benign isolated hysterectomy, pelvic organ prolapse repair, or anti-incontinence procedures were identified between October 2015 and December 2019. INTERVENTIONS: HAs are topically applied procoagulant products used for surgical hemostasis and use during included encounters was determined by charge codes. MEASUREMENTS AND MAIN RESULTS: Subject-, hospital-, and surgeon-level characteristics and costs were captured. Data were initially analyzed in the aggregate and based on procedure category using the chi-square test or independent samples t tests as appropriate. A bootstrap forest model was used to identify the factors most predictive of HA use. In the final cohort of 184 070 encounters, HAs were used most frequently in hysterectomy (20.7%) and least in anti-incontinence surgery (10.9%). The use of HAs increased from 15.6% in quarter 4 2015 to 19.2% in quarter 4 2019 (p <.001). Encounters using HAs cost more than encounters without HAs ($6271.10 vs $4572.00; p <.001). A bootstrap forest model inclusive of all variables found surgeon and hospital identity cumulatively predictive of 84.9% of HA use, 65.5% and 19.4%, respectively. There was significant variation in HA use among individual surgeons, with 59.9% never using HAs. Of those who did use HAs, 72.8% used HAs more frequently than the mean provider HA use rate (19.4%) and 9.2% used HAs in every case he/she performed. CONCLUSION: The significant variation in HA use is driven primarily by physician and hospital identity, suggesting that use of HA in these benign gynecologic surgical contexts may be determined more by physician- and hospital-level factors than patient-level factors.

Feasibility as a mechanism for model identification and validation.

As new technologies permit the generation of hitherto unprecedented volumes of data (e.g. genome-wide association study data), researchers struggle to keep up with the added complexity and time commitment required for its analysis. For this reason, model selection commonly relies on machine learning and data-reduction techniques, which tend to afford models with obscure interpretations. Even in cases with straightforward explanatory variables, the so-called 'best' model produced by a given model-selection technique may fail to capture information of vital importance to the domain-specific questions at hand. Herein we propose a new concept for model selection, feasibility, for use in identifying multiple models that are in some sense optimal and may unite to provide a wider range of information relevant to the topic of interest, including (but not limited to) interaction terms. We further provide an R package and associated Shiny Applications for use in identifying or validating feasible models, the performance of which we demonstrate on both simulated and real-life data.

Clinician Opinions and Approaches to Manage Risk Related to Safe Sleep During Skin-to-Skin Care.

OBJECTIVE: To understand the opinions of clinicians about the risks, benefits, barriers, and facilitators to the practice of parent sleep during skin-to-skin care in hospital settings. DESIGN: Cross-sectional survey. SETTING: Online survey. PARTICIPANTS: Clinicians who self-identified as infant care providers, that is, neonatal clinicians (N = 158). METHODS: We sent an online survey invitation to neonatal clinicians through neonatal websites, conferences, and social media sites in the United States and used snowball recruitment. We used a risk management framework to analyze qualitative data. We used descriptive statistics and the chi-square and Fisher's exact tests to determine if opinions differed based on clinician and organizational characteristics. RESULTS: Respondents' support of parent sleep during skin-to-skin care (yes/no) did not differ on the basis of whether the clinician had taken a formal course on skin-to-skin care, facilitated skin-to-skin care more than 100 times, or frequently promoted skin-to-skin care in current practice. Respondents who supported parent sleep (n = 93, 59% of respondents) reported greater implementation of risk control strategies than nonsupporters (n = 53 [57%] vs. n = 3 [5%]; p < .001), such as frequent monitoring of vital signs (n = 33 [35%] vs. n = 2 [3%]; p < .001), use of devices to support skin-to-skin care (n = 49 [53%] vs. n = 19 [29%]; p = .003), and proper positioning (n = 20 [22%] vs. n = 0 [0%]; p < .001). Nonsupporters more frequently reported that parent sleep during skin-to-skin care violates safe sleep recommendations, is habit forming for home, poses a fall risk, and jeopardizes the infant's airway. CONCLUSION: Most respondents supported parent sleep during skin-to-skin care, but concerns regarding safety for the infant remained a barrier. The use of a risk management framework may help facilitate a systematic approach to improve the implementation of safe skin-to-skin practices.

Live fast, diversify non-adaptively: evolutionary diversification of exceptionally short-lived annual killifishes.

BACKGROUND: Adaptive radiations are triggered by ecological opportunity - the access to novel niche domains with abundant available resources that facilitate the formation of new ecologically divergent species. Therefore, as new species saturate niche space, clades experience a diversity-dependent slowdown of diversification over time. At the other extreme of the radiation continuum, non-adaptively radiating lineages undergo diversification with minimal niche differentiation when 'spatial opportunity' (i.e. areas with suitable 'ancestral' ecological conditions) is available. Traditionally, most research has focused on adaptive radiations, while empirical studies on non-adaptive radiations remain lagging behind. A prolific clade of African fish with extremely short lifespan (Nothobranchius killifish), show the key evolutionary features of a candidate non-adaptive radiation - primarily allopatric species with minimal niche and phenotypic divergence. Here, we test the hypothesis that Nothobranchius killifish have non-adaptively diversified. We employ phylogenetic modelling to investigate the tempo and mode of macroevolutionary diversification of these organisms. RESULTS: Nothobranchius diversification has proceeded with minor niche differentiation and minimal morphological disparity among allopatric species. Additionally, we failed to identify evidence for a role of body size or biogeography in influencing diversification rates. Diversification has been homogeneous within this genus, with the only hotspot of species-richness not resulting from rapid diversification. However, species in sympatry show higher disparity, which may have been caused by character displacement among coexisting species. CONCLUSIONS: Nothobranchius killifish have proliferated following the tempo and mode of a non-adaptive radiation. Our study confirms that this exceptionally short-lived group have diversified with minimal divergent niche adaptation, while one group of coexisting species seems to have facilitated spatial overlap among these taxa via the evolution of ecological character displacement.

Size and shape distributions of primary crystallites in titania aggregates.

The primary crystallite size of titania powder relates to its properties in a number of applications. Transmission electron microscopy was used in this interlaboratory comparison (ILC) to measure primary crystallite size and shape distributions for a commercial aggregated titania powder. Data of four size descriptors and two shape descriptors were evaluated across nine laboratories. Data repeatability and reproducibility was evaluated by analysis of variance. One-third of the laboratory pairs had similar size descriptor data, but 83% of the pairs had similar aspect ratio data. Scale descriptor distributions were generally unimodal and were well-described by lognormal reference models. Shape descriptor distributions were multi-modal but data visualization plots demonstrated that the Weibull distribution was preferred to the normal distribution. For the equivalent circular diameter size descriptor, measurement uncertainties of the lognormal distribution scale and width parameters were 9.5% and 22%, respectively. For the aspect ratio shape descriptor, the measurement uncertainties of the Weibull distribution scale and width parameters were 7.0% and 26%, respectively. Both measurement uncertainty estimates and data visualizations should be used to analyze size and shape distributions of particles on the nanoscale.