Tag: statistics

Influence of Antagonist Material on Fatigue and Fracture Resistance of Zirconia Crowns.

Eur J Dent. 2020 Apr 20;:

Authors: Nawafleh N, Bibars AR, Al Twal E, Öchsner A

Abstract
OBJECTIVES:  This study investigates the influence of the most commonly used indenter materials on fatigue survival and fracture resistance of zirconia crowns.
MATERIALS AND METHODS:  A total of 40 zirconia crowns were prepared using computer-aided design (CAD)/computer-aided manufacturing (CAM) technology: 30 crowns were divided into three experimental groups of 10 specimens and the last 10 specimens acted as the control group. The experimental groups were subjected to chewing simulation with simultaneous thermocycling. Three indenter materials (steatite ceramic, stainless steel, and tungsten carbide) with identical diameter were used to load the specimens. All crowns were then subjected to single load to fracture test in universal testing machine. Load was applied vertically with a crosshead speed of 1 mm/min until failure, and fracture load was recorded.
STATISTICAL ANALYSIS:  Normal distribution of data was confirmed using the Shapiro-Wilk test. Descriptive statistics including means and standard deviations were determined for all groups. Differences between groups were tested using Dunnett’s test and paired sample t-test.
RESULTS:  Chewing simulation for 1.2 million cycles resulted in 100% survival. The highest mean fracture load was recorded for the control group and the lowest one was for the group fatigued with stainless steel indenter. Chewing simulation statistically significantly (p < 0.05) reduced the mean fracture load of the crowns fatigued with stainless steel and steatite ceramic indenter. However, the mean fracture load for the crowns fatigued with tungsten carbide was not significantly different from that of the control group.
CONCLUSION:  Steatite ceramic and stainless steel indenters produced close results and significantly reduced fracture load of zirconia crowns. However, tungsten carbide indenter caused nonsignificant reduction in the fracture load of zirconia crowns.

PMID: 32311751 [PubMed – as supplied by publisher]

Variations in Surgical Outcomes of Carotid Body Tumors by Surgical Specialty.

Laryngoscope. 2020 Apr 20;:

Authors: Melachuri S, Valappil B, Snyderman C

Abstract
OBJECTIVES/HYPOTHESIS: A carotid body tumor (CBT) is a rare type of tumor that is divided among multiple surgical specialties. Individual surgeons may have limited experience in treating these tumors. We aim to compare different surgical specialties within a single healthcare system to detect variations in management and outcome.
STUDY DESIGN: Retrospective chart review.
METHODS: A chart review of all patients who underwent surgery for CBT at the University of Pittsburgh Medical Center (UPMC) from 2000 to 2019 was carried out. Univariate and multivariate analysis was used for descriptive statistics, comparison of outcomes, and identification of risk factors.
RESULTS: Fifty-eight CBT resection surgeries were performed at UPMC. Patients with advanced tumor were 6.7 (95% confidence interval [CI]: 1.36-32.7) times more likely to undergo preoperative embolization and 8.53 (95% CI: 2.011-36.19) times more likely to sustain carotid artery injury. Advanced-stage tumor resections were associated with greater blood loss (P = .03) and longer hospitalization (P = .02). Collaborative surgeries were associated with higher rates of carotid artery injury (P = .003), residual tumor (P < .001), and longer hospitalization (P = .003), as these combined cases were generally reserved for advanced-stage tumors (P = .02). There were no differences in outcomes between specialties. Of 22 surgeons, the median number of surgeries per surgeon was one (range = 1-12, 54.5%).
CONCLUSIONS: Surgeons who completed only one surgery for CBT had a greater rate of hospital readmission and greater length of hospital stay. Collaborative surgeries had worse outcomes due to more advanced tumors requiring more complex surgeries.
LEVEL OF EVIDENCE: 4 Laryngoscope, 2020.

PMID: 32311766 [PubMed – as supplied by publisher]

Parental incarceration and youth tobacco product use: Implications for prevention and the e-cigarette epidemic.

Addict Behav. 2020 Apr 03;107:106428

Authors: Parks MJ, Davis L, Wilhelm AK, McMorris BJ, Borowsky IW, Shlafer RJ

Abstract
PURPOSE: Youth smokers have high rates of adverse childhood experiences, and particularly parental incarceration (PI). In Minnesota, 16% of youth have experienced PI, but 55% of daily smokers report PI. However, no research has examined how PI relates to a range of tobacco products, which is critical considering the current e-cigarette epidemic. There is also limited research on protective factors for tobacco use among youth with PI.
METHODS: Data came from 2016 Minnesota Student Survey (N = 111,091); 85% of Minnesota schools participated. We assessed 30-day use of cigarettes, non-cigarette combustible products, smokeless products, e-cigarettes, and dual/poly use. Using descriptive statistics and logistic regressions, we compared use across current, previous, and no PI experience. We also tested how protective factors related to tobacco use.
RESULTS: Youth with current PI experience used all products with higher frequency compared to youth with previous and no PI experience. Use prevalence among youth with current PI were 26.0% (95% CI = 24.1, 27.8) for e-cigarettes, 20.8% (95% CI = 19.1, 22.5) for dual/poly use, 17.8% (95% CI = 16.2, 19.5) for cigarettes, 17.4% (95% CI = 15.8, 19.0) for combustible non-cigarettes, and 9.9% (95% CI = 8.6, 11.2) for smokeless products. Nearly all protective factors were significantly and negatively related to use of all products, regardless of PI experience.
CONCLUSIONS: Youth with PI experience are at high risk for using multiple tobacco products. These disparities were most pronounced for e-cigarettes, demonstrating the e-cigarette epidemic is disproportionately occurring among youth with current and previous PI experience. All examined protective factors buffer risks for this population of youth.

PMID: 32311626 [PubMed – as supplied by publisher]

Randomized sketches for kernel CCA.

Neural Netw. 2020 Apr 14;127:29-37

Authors: Lian H, Zhang F, Lu W

Abstract
Kernel canonical correlation analysis (KCCA) is a popular tool as a nonlinear extension of canonical correlation analysis. Consistency and optimal convergence rate have been established in the literature. However, the time complexity of KCCA scales as O(n3) and is thus prohibitive when n is large. We propose an m-dimensional randomized sketches approach for KCCA with m<<n, based on the recent work on randomized sketches for kernel ridge regression (KRR). Technically we establish our theoretical results relying on an interesting connection between KCCA and KRR by utilizing a novel “duality tracking” device that alternates between the infinite-dimensional operator-theory-based view of KCCA and the finite-dimensional kernel-matrix-based view.

PMID: 32311655 [PubMed – as supplied by publisher]

Identification and Management of Progressive Enhancement after Radiation Therapy for Brain Metastases: Results from a Neurosurgical Survey.

World Neurosurg. 2020 Apr 17;:

Authors: Semonche A, Patel N, Yang I, Danish S

Abstract
OBJECTIVE: There is a lack of consensus regarding diagnosis, timing, and method of intervention for progressive enhancement on surveillance imaging after stereotactic radiosurgery (SRS) treatment of brain metastases. We sought to characterize current practices among neurosurgeons in identifying and treating infield tumor recurrence (TR) or radiation necrosis (RN) after SRS for brain metastases. MethodsVoluntary survey distributed electronically to pre-identified neurosurgeons. Results were analyzed using descriptive statistics and chi-square analysis. Results120 participants completed the survey from 72 United States and 17 international centers. The majority (69.2%) agreed that growth over at least 2 surveillance scans spaced at least 90 days apart identified irreversible progression after SRS for brain metastases. Respondents were evenly divided on the need for tissue biopsy to distinguish between TR and RN. Preferred treatment modality and timeframe to initiate treatment of suspected RN differed among neurosurgeons based on SRS case volume for brain metastases (P=.002 and P=.02, respectively). Neurosurgeons who utilized magnetic resonance-guided laser interstitial thermal therapy (LITT) for brain metastases were more likely to prefer LITT for suspected RN whereas those with minimal LITT experience preferred steroids (P<0.0001). Neurosurgeons in the United States were more likely to prefer LITT for RN (37.3%) compared to international counterparts (0%).
CONCLUSION: Our survey of practicing neurosurgeons highlights areas of controversy in distinguishing between TR and RN and preferred management of suspected RN.

PMID: 32311550 [PubMed – as supplied by publisher]

Improvement of sudden cardiac death risk prediction by enhanced ACC/AHA strategy in Chinese patients with hypertrophic cardiomyopathy.

Heart Rhythm. 2020 Apr 17;:

Authors: Liu J, Wu G, Zhang C, Ruan J, Wang D, Zhang M, Wang L, Yang Y, Li X, Wang Y, Hui R, Zou Y, Kang L, Wang J, Song L

Abstract
BACKGROUND: The lack of validated and effective sudden cardiac death (SCD) risk prediction method is the biggest barrier to perform the lifesaving treatment of prophylactic implantable cardioverter defibrillator (ICD) in Chinese patients with hypertrophic cardiomyopathy (HCM).
OBJECTIVE: This study aimed to evaluate the efficacy of three existing SCD risk prediction methods, namely 2011 American College of Cardiology Foundation and American Heart Association (ACCF/AHA) guideline, 2014 European Society of Cardiology (ESC) guideline and 2019 enhanced ACC/AHA strategy in Chinese patients with HCM.
METHODS: The present study consisted of 1369 consecutive adult HCM patients without a history of SCD events. The primary endpoint was a composite of SCD and equivalent events, namely resuscitation from cardiac arrest and appropriate ICD shock therapy for ventricular tachycardia or fibrillation.
RESULTS: During follow-up of 3.2±2.4 years, 39 patients reached SCD endpoints, among which 26 (66.7%) were correctly predicted as high-risk of SCD by 2019 enhanced ACC/AHA strategy, 20 (51.3%) by 2011 ACCF/AHA guideline, but only 5 (12.8%) by 2014 ESC guideline, prospectively. The 2019 enhanced ACC/AHA strategy showed higher C-statistics (0.647) for SCD prediction than 2011 ACCF/AHA guideline (0.598) and 2014 ESC guideline (0.605), and resulted in correct reclassification of SCD risk when compared with 2011 ACCF/AHA (Net Reclassification Index=0.113, P=0.074) and 2014 ESC guideline (Net Reclassification Index=0.245, P=0.038).
CONCLUSION: The 2019 enhanced ACC/AHA strategy showed better predictive performance for SCD risk stratification in Chinese HCM patients, with a notably high sensitivity.

PMID: 32311532 [PubMed – as supplied by publisher]

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