Category: Statistics

Thromb Res. 2021 Feb 18;201:1-5. doi: 10.1016/j.thromres.2021.02.015. Online ahead of print.

ABSTRACT

BACKGROUND: Venous thromboembolism (VTE) may be the first symptom of cancer. Statins are suggested to prevent VTE, but the risk of cancer in VTE patients using statins remains poorly understood.

OBJECTIVES: To examine if VTE is a marker of cancer in users of statins.

METHODS: We identified all Danish patients during 1996-2017 with a first-time diagnosis of VTE and a filled prescription for a statin within 90 days prior to the VTE diagnosis. We classified patients as prevalent users if the first filling of a statin occurred more than one year preceding the VTE diagnosis, and as new users if the first filling occurred within the preceding year. We computed cumulative incidences of cancer, with death as a competing risk, and age-, sex-, and calendar-period standardized incidence ratios (SIRs), comparing the observed cancer incidence with the expected based on national cancer statistics.

RESULTS: Among 9280 (85%) prevalent users of statin and 1580 (15%) new users, the one-year cumulative incidence of any cancer was 6.6 (95% CI: 6.1-7.2) for prevalent users and 6.4 (95% CI: 5.2-7.6) for new users; the corresponding SIRs were 3.1 (95% CI: 2.9-3.3) and 3.5 (95% CI: 2.9-4.3). In the second and subsequent years, the SIRs diminished and approached unity for both prevalent (1.1 [95% CI: 1.1-1.2]) and new users (1.1 [95% CI: 0.9-1.3]).

CONCLUSIONS: VTE patients using statins had a 3-fold increased rate of cancer in the first year after diagnosis. A first VTE serves as an important marker of cancer, regardless of statin use.

PMID:33621859 | DOI:10.1016/j.thromres.2021.02.015

Thromb Res. 2021 Feb 18;201:6-14. doi: 10.1016/j.thromres.2021.02.017. Online ahead of print.

ABSTRACT

INTRODUCTION: In heparin-induced thrombocytopenia (HIT), selected patients are treated with therapies directed at the immune response, intravenous immunoglobulin (IVIG) and therapeutic plasma exchange (TPE). To determine IVIG and TPE characteristics and outcomes in HIT, we analyzed the National Inpatient Sample (NIS) database.

METHODS: In a population-based analysis of the NIS, we identified hospital discharges of adult patients with a HIT diagnosis. A two-level statistical analysis was performed comparing cases as follows 1) IVIG or TPE vs. none; and 2) IVIG vs. TPE. For each analysis, the primary outcome was in-hospital mortality. Secondary outcomes were thrombotic events, major bleeding, infections, hospital length of stay, and total charges.

RESULTS: Among 22,152 discharges with a HIT diagnosis, 77 (0.34%) and 52 (0.23%) received TPE and IVIG, respectively. In the first level analysis of TPE or IVIG vs. no treatment, TPE or IVIG treatment was associated with a higher likelihood of in-hospital mortality (OR = 1.85; 95%CI: 1.13-3.03, p = 0.0104), major bleeding (OR = 1.91; 95%CI: 1.25-2.93, p = 0.0030), gastrointestinal bleeding (OR = 1.89; 95%CI: 1.08-3.30, p = 0.0259), and infection (OR = 1.65; 95% CI:1.13-2.41, p = 0.0095). In the second-level analysis comparing IVIG vs. TPE, there were no significant differences in patient characteristics or outcomes in both unadjusted and adjusted analyses.

CONCLUSIONS: In this population-based analysis of HIT, we found similar outcomes of IVIG and TPE-treated cases. Given the small sample size, future studies are needed to confirm this observation.

PMID:33621860 | DOI:10.1016/j.thromres.2021.02.017

Ultrason Sonochem. 2021 Jan 11;73:105459. doi: 10.1016/j.ultsonch.2020.105459. Online ahead of print.

ABSTRACT

Ultrasonic flotation was an effective method to float fine coal. In this study, the effects of the standing waves with different frequencies on ultrasonic flotation were investigated. The dynamic processes of bubble and coal-bubble were revealed by a high-speed camera. The results showed that under the action of Bjerknes force, bubble aggregates were formed within 450 ms and coal bubble aggregates were formed within 20 ms. The bubble aggregates were statistically analyzed by image processing method. The number of aggregates and small bubbles in the ultrasonic field at 100 kHz was greater than those at 80 and 120 kHz. Besides, 100 kHz ultrasonic flotation achieved the highest yields of clean coal (35.89%) and combustible recovery (45.77%). The cavitation bubbles acted as either a “medium” or an “inclusion”, entrapping and entraining the coal particles in the flotation pulp. It promoted the aggregation of bubbles with coal particles, so the flotation efficiency was effectively improved in the presence of ultrasonic standing waves.

PMID:33621851 | DOI:10.1016/j.ultsonch.2020.105459

Am J Transplant. 2021 Feb 23. doi: 10.1111/ajt.16552. Online ahead of print.

ABSTRACT

Organ procurement organizations (OPO) test potential deceased organ donors for infectious diseases required by policy, but many also perform testing for additional infections. The current state of donor testing in the United States is unknown. We sent an IRB approved survey to all 57 U.S. OPOs using REDCap. Descriptive statistics were performed. From the 57 OPOs, we received 46 (80.7%) unique responses with all 11 United Network of Organ Sharing regions represented. Forty of 46 (87%) OPO respondents consulted an Infectious Diseases physician when needed. Eighteen of 46 (39%) tested for West Nile virus (WNV) and 17 of 18 (94%) tested year-round. Eleven of 46 (23.9%) tested for Strongyloides infection while 17 of 46 (37%) tested for Chagas disease. All OPOs performed prospective nucleic acid testing (NAT) for HIV, hepatitis B and hepatitis C on all donors. OPO testing of additional infections has increased since prior surveys but remains variable. Standardization of organ donor infectious diseases evaluation should be considered.

PMID:33621430 | DOI:10.1111/ajt.16552

ACR Open Rheumatol. 2021 Feb 23. doi: 10.1002/acr2.11229. Online ahead of print.

ABSTRACT

OBJECTIVE: To determine the validity of self-reported physician diagnosis of rheumatoid arthritis (RA) using multiple gold-standard measures based on Medicare claims in a nationally representative sample of older adults and to verify whether additional questions about taking medication and having seen a physician in the past two years for arthritis can improve the positive predictive value (PPV) and other measures of the validity of self-reported RA.

METHODS: A total of 3768 Medicare-eligible respondents with and without incident self-reported RA were identified from the 2004, 2008, and 2012 waves of the United States Health and Retirement Study. Self-reported RA was validated using the following three claims-based algorithms: 1) a single International Classification of Diseases, ninth edition, Clinical Modification claim for RA, 2) two or more claims no greater than 2 years apart, and 3) two or more claims with at least one diagnosis by a rheumatologist. Additional self-report questions of medication use and having seen a doctor for arthritis in the past two years were validated against the same criteria.

RESULTS: A total of 345 respondents self-reported a physician diagnosis of RA. Across all three RA algorithms, the PPV of self-report ranged from 0.05 to 0.16., the sensitivity ranged from 0.23 to 0.55., and the κ statistic ranged from 0.07 to 0.15. Additional self-report data regarding arthritis care improved the PPV and other validity measures of self-report; however, the values remained low.

CONCLUSION: Most older adults who self-report RA do not have a Medicare claims history consistent with that diagnosis. Revisions to current self-reported RA questions may yield more valid identification of RA in national health surveys.

PMID:33621434 | DOI:10.1002/acr2.11229

PLoS One. 2021 Feb 23;16(2):e0247683. doi: 10.1371/journal.pone.0247683. eCollection 2021.

ABSTRACT

Essential fructosuria (EF) is a benign, asymptomatic, autosomal recessive condition caused by loss-of-function variants in the ketohexokinase gene and characterized by intermittent appearance of fructose in the urine. Despite a basic understanding of the genetic and molecular basis of EF, relatively little is known about the long-term clinical consequences of ketohexokinase gene variants. We examined the frequency of ketohexokinase variants in the UK Biobank sample and compared the cardiometabolic profiles of groups of individuals with and without these variants alone or in combination. Study cohorts consisted of groups of participants defined based on the presence of one or more of the five ketohexokinase gene variants tested for in the Affymetrix assays used by the UK Biobank. The rs2304681:G>A (p.Val49Ile) variant was present on more than one-third (36.8%) of chromosomes; other variant alleles were rare (<1%). No participants with the compound heterozygous genotype present in subjects exhibiting the EF phenotype in the literature (Gly40Arg/Ala43Thr) were identified. The rs2304681:G>A (p.Val49Ile), rs41288797 (p.Val188Met), and rs114353144 (p.Val264Ile) variants were more common in white versus non-white participants. Otherwise, few statistically or clinically significant differences were observed after adjustment for multiple comparisons. These findings reinforce the current understanding of EF as a rare, benign, autosomal recessive condition.

PMID:33621267 | DOI:10.1371/journal.pone.0247683

Pain Med. 2021 Feb 23;22(2):444-458. doi: 10.1093/pm/pnaa403.

ABSTRACT

OBJECTIVE: This pilot trial examined the effects of a combined intervention of mindfulness meditation followed by aerobic walking exercise compared with a control condition in chronic low back pain patients. We hypothesized that meditation before exercise would reduce disability, pain, and anxiety by increasing mindfulness prior to physical activity compared with an audiobook control group.

PARTICIPANTS: Thirty-eight adults completed either meditation and exercise treatment (MedExT) (n=18) or an audiobook control condition (n=20).

SETTING: Duquesne University Exercise Physiology Laboratory.

DESIGN: A pilot, assessor-blinded, randomized controlled trial.

METHODS: Over a 4-week period, participants in the MedExT group performed 12-17 minutes of guided meditation followed by 30 minutes of moderate-intensity walking exercise 5 days per week. Measures of disability, pain, mindfulness, and anxiety were taken at baseline and postintervention. Pain perception measurements were taken daily.

RESULTS: Compared with the control group, we observed larger improvements in disability in the MedExT intervention, although the changes were modest and not statistically significant (mean between-group difference, -1.24; 95% confidence interval [CI], -3.1 to 0.6). For secondary outcome measures, MedExT increased mindfulness (within-group) from pre-intervention to postintervention (P=0.0141). Additionally, mean ratings of low back pain intensity and unpleasantness significantly improved with time for the MedExT group compared with that of the control group, respectively (intensity P=0.0008; unpleasantness P=0.0022).

CONCLUSION: . Overall, 4 weeks of MedExT produced suggestive between-group trends for disability, significant between-group differences for measures of pain, and significant within-group increases in mindfulness.

PMID:33621332 | DOI:10.1093/pm/pnaa403

Med Phys. 2021 Feb 23. doi: 10.1002/mp.14795. Online ahead of print.

ABSTRACT

PURPOSE: Statistical process control tools such as control charts were recommended by the American Association of Physicists in Medicine (AAPM) Task Group 218 for radiotherapy quality assurance. However, the tools needed to analyze multivariate, correlated data that is often encountered in treatment plan quality measures, are lacking. In this study, we develop quality control tools that can model multivariate plan quality measures with correlations and account for patient-specific risk-factors, without adding a significant burden to clinical workflow.

METHODS AND MATERIALS: A multivariate, quality control chart is developed that includes a risk-adjustment model, Hotelling’s T² statistic, and principal component analysis (PCA). PCA accounts for correlations among a set of organ-at-risk (OAR) dose-volume histogram (DVH) points that serves as proxies for plan quality. Risk-adjustment models estimate the principal components from PCA using a set of patient- and treatment-specific risk factors. The resulting residuals from the risk-adjustment models are used to compute the Hotelling’s T² statistic; the corresponding multivariate control chart is then plotted based on the beta distribution followed by the statistic. Further, the box-cox transformation is used to account for non-normality in DVH points. We investigate the application of the proposed methodology via three multivariate control charts-a conventional chart that ignores risk-adjustment and PCA, a risk-adjusted chart ignoring PCA, and a PCA-based, risk-adjusted chart. These control charts are evaluated on 69 head-and-neck cases.

RESULTS: The conventional multivariate control chart fails to account for important patient-specific risk factors, including volumes and cross-sectional areas of the tumor and OARs and distances in-between. This failure leads to a larger number of false alarms. While the multivariate risk-adjusted control chart is able to reduce false alarms, it fails to account for correlations in DVH points. The multivariate PCA-based, risk-adjusted control chart can detect unusual plans after accounting for the correlations. By replanning, improvements are shown on an unusual plan identified by both risk-adjusted methods.

CONCLUSIONS: The multivariate risk-adjusted control chart developed here enables quality control of plans prior to delivery. This methodology is generic and can be readily applied for other radiotherapy quality assurance protocols, such as gamma analysis pass-rates.

PMID:33621381 | DOI:10.1002/mp.14795

Clin Physiol Funct Imaging. 2021 Feb 23. doi: 10.1111/cpf.12696. Online ahead of print.

ABSTRACT

Flow-mediated vasodilatation (FMD) has become one of the most widely assessed parameters to analyze endothelial and vascular function in cardiovascular medicine. The degree of contribution of nitric oxide (NO) to FMD is inconclusive and varies widely depending on the device used. In this study we used a semi-automatic ultrasound device to analyze to what extent basal NO activity contributes to FMD of the brachial artery. FMD was assessed with the UNEX EF device in a cross-over single blinded randomized study at baseline and then during infusion of either a NO-synthase-inhibitor (NG-monomethyl-L-arginine (L-NMMA)) or saline. The analysis was repeated after 1 week with the alternative infusion of L-NMMA or saline. All measurements were analyzed both automatically and by a technician manually. In total 25 healthy men subjects completed the study. Diastolic blood pressure and heart rate significantly changed during infusion of L-NMMA. Infusion of L-NMMA reduced FMD significantly (-37%, p=0.002). Saline solution had no effect on FMD (+14%, p=0.392). Change in FMD was significantly different between the groups (ΔFMD_L-NMMA vs. ΔFMD_saline , p=0.032). There was a statistically significant correlation between automatically analyzed results and those obtained by an experienced technician (FMD_saline : r=0.822, p<0.001; FMD_L-NMMA : r=0.645, p=0.007). The influence of NO on FMD is approximately 40% if assessed using the UNEX EF. Prior to use FMD as a marker of endothelial dysfunction we should explore different methods including various duration of forearm ischaemia to increase NO dependency of FMD.

PMID:33621423 | DOI:10.1111/cpf.12696

PLoS Comput Biol. 2021 Feb 23;17(2):e1008734. doi: 10.1371/journal.pcbi.1008734. eCollection 2021 Feb.

ABSTRACT

The collective behaviour of animal and human groups emerges from the individual decisions and actions of their constituent members. Recent research has revealed many ways in which the behaviour of groups can be influenced by differences amongst their constituent individuals. The existence of individual differences that have implications for collective behaviour raises important questions. How are these differences generated and maintained? Are individual differences driven by exogenous factors, or are they a response to the social dilemmas these groups face? Here I consider the classic case of patch selection by foraging agents under conditions of social competition. I introduce a multilevel model wherein the perceptual sensitivities of agents evolve in response to their foraging success or failure over repeated patch selections. This model reveals a bifurcation in the population, creating a class of agents with no perceptual sensitivity. These agents exploit the social environment to avoid the costs of accurate perception, relying on other agents to make fitness rewards insensitive to the choice of foraging patch. This provides a individual-based evolutionary basis for models incorporating perceptual limits that have been proposed to explain observed deviations from the Ideal Free Distribution (IFD) in empirical studies, while showing that the common assumption in such models that agents share identical sensory limits is likely false. Further analysis of the model shows how agents develop perceptual strategic niches in response to environmental variability. The emergence of agents insensitive to reward differences also has implications for societal resource allocation problems, including the use of financial and prediction markets as mechanisms for aggregating collective wisdom.

PMID:33621223 | DOI:10.1371/journal.pcbi.1008734