Tag: statistics

Psychometrika. 2021 Mar 26. doi: 10.1007/s11336-021-09755-4. Online ahead of print.

ABSTRACT

The likelihood ratio test is widely used in exploratory factor analysis to assess the model fit and determine the number of latent factors. Despite its popularity and clear statistical rationale, researchers have found that when the dimension of the response data is large compared to the sample size, the classical Chi-square approximation of the likelihood ratio test statistic often fails. Theoretically, it has been an open problem when such a phenomenon happens as the dimension of data increases; practically, the effect of high dimensionality is less examined in exploratory factor analysis, and there lacks a clear statistical guideline on the validity of the conventional Chi-square approximation. To address this problem, we investigate the failure of the Chi-square approximation of the likelihood ratio test in high-dimensional exploratory factor analysis and derive the necessary and sufficient condition to ensure the validity of the Chi-square approximation. The results yield simple quantitative guidelines to check in practice and would also provide useful statistical insights into the practice of exploratory factor analysis.

PMID:33770318 | DOI:10.1007/s11336-021-09755-4

Support Care Cancer. 2021 Mar 26. doi: 10.1007/s00520-021-06166-0. Online ahead of print.

ABSTRACT

OBJECTIVE: This study aims to evaluate the treatment effect of a mindfulness-based intervention for Chinese breast cancer patients across outcome domains, including symptom-related, psychosocial, and quality of life outcomes.

METHODS: Following the Cochrane Systematic Review guideline, we searched across five electronic databases, reference lists of eligible studies, professional websites, and major academic journals in Chinese. Publication bias was assessed using funnel plot and Vevea and Woods sensitivity analysis, and risk of bias was evaluated using the revised Cochrane risk of bias tool for randomized trials and risk of bias in non-randomized studies of interventions. A meta-analysis of Hedges’ g was conducted using meta-regression with robust variance estimation.

RESULTS: Final analysis included a total of 45 controlled trials containing 286 effect size estimates. Across outcome domains, studies reported an overall large and statistically significant treatment effect, d = 0.921, 95% CI (0.805, 1.040), p < 0.001. Subgroup analyses of specific domains of outcome reported overall significant treatment effects for (1) symptom-related outcomes, d = 0.885, 95% CI (0.657, 1.110), p < 0.001; (2) psychosocial wellness outcomes, d = 0.984, 95% CI (0.879, 1.090), p < 0.001; and (3) quality of life, d = 0.990, 95% CI (0.776, 1.200), p < 0.001. Moderator analysis did not identify any significant moderator.

CONCLUSION: Chinese literature reported an overall statistically significant and large treatment effect of a mindfulness-based intervention for breast cancer patients in China. Except for physical symptom outcomes, e.g., nausea/vomiting and pain, a mindfulness-based intervention was effective across outcome domains among Chinese breast cancer patients.

PMID:33770259 | DOI:10.1007/s00520-021-06166-0

Graefes Arch Clin Exp Ophthalmol. 2021 Mar 26. doi: 10.1007/s00417-021-05165-5. Online ahead of print.

ABSTRACT

PURPOSE: To assess the long-term outcomes of transcanalicular laser dacryocystorhinostomy in cases of primary acquired nasolacrimal duct obstruction (PANDO).

METHODS: Retrospective interventional case series was performed on all patients diagnosed with PANDO and who underwent a primary transcanalicular laser dacryocystorhinostomy from Jan 2014 to June 2016. The procedure was performed using 980 nm diode laser. All the patients additionally underwent intraoperative adjunctive procedures: mitomycin C application and silicone intubation. Patients were followed for up to 3 years after surgery. Anatomical success was defined as patent ostium on irrigation, and functional success was defined as resolution of epiphora. The parameters studied include patient demographics, clinical presentation, type of anesthesia, duration of surgery, laser energy delivered, complications, and anatomical and functional success. The variables influencing the outcomes were assessed. Statistical analysis was performed using the package Statistica (version 10.0, Statsoft, Poland).

RESULTS: A total number of 205 patients were assessed. Of these, 73.17% (150/205) were females. The mean age of patients was 62.92 years. The mean laser energy used was 1060.09 J, and the mean operating time was 22.33 min. Approximately, 95% and 68% of the patients completed 1 year and 3 years of follow-up, respectively. The anatomical and functional success rates dropped significantly beyond the 3 months and 6 months postoperative period and maintained the lower success rates beyond 1-year follow-up for up to 3 years. The anatomical and functional success at the end of 3-year follow-up was 56.12% and 33.81%, respectively. The functional success was not affected by gender (P = 0.132), age (P = 0.956), laser energy (P = 0.626), or duration of the surgery (P = 0.906). However, the intraoperative pain scale was influenced by the laser energy (P < 0.001) and the duration of the surgery (P < 0.001).

CONCLUSION: The anatomical and functional outcomes of primary transcanalicular laser dacryocystorhinostomy are suboptimal and not encouraging in the long term.

PMID:33770269 | DOI:10.1007/s00417-021-05165-5

Pediatr Nephrol. 2021 Mar 26. doi: 10.1007/s00467-021-04999-9. Online ahead of print.

ABSTRACT

BACKGROUND: Acute kidney Injury (AKI) in children undergoing cardiac surgery (CS) is strongly associated with hospital morbidity. Post-discharge CS AKI outcomes are less clear. We evaluated associations between AKI and post-discharge (a) healthcare utilization, (b) chronic kidney disease (CKD) or hypertension and (c) mortality.

METHODS: This is a retrospective two-centre cohort study of children surviving to hospital discharge after CS. Primary exposures were post-operative ≥Stage 1 AKI and ≥Stage 2 AKI defined by Kidney Disease Impoving Global Outcomes. Association of AKI with time to outcomes was determined using multivariable Cox-Proportional Hazards analysis.

RESULTS: Of 350 participants included (age 3.1 (4.5) years), 180 [51.4%] developed AKI and 60 [17.1%] developed ≥Stage 2 AKI. Twenty-eight (9%) participants developed CKD or hypertension (composite outcome), and 17 (5%) died within 5 years of discharge. Post-operative ≥Stage 1 and ≥Stage 2 AKI were not associated with post-discharge hospitalizations, emergency room (ER) visits, physician visits or CKD or hypertension in adjusted analyses. A trend was observed between ≥Stage 2 AKI and mortality but was not statistically significant. In unadjusted stratified analyses, AKI was associated with post-discharge hospitalizations in children with RACHS-1 score ≥3, complex chronic disease classification and children living in urban areas.

CONCLUSIONS: Post-CS AKI is not associated with post-discharge healthcare utilization, death and CKD or hypertension, though it may be associated with healthcare utilization in more complex paediatric CS children. Studies should aim to better understand post-CS healthcare utilization patterns and non-AKI risk factors for CKD, hypertension and mortality, to reduce adverse long-term outcomes after CS.

PMID:33770283 | DOI:10.1007/s00467-021-04999-9

Abdom Radiol (NY). 2021 Mar 26. doi: 10.1007/s00261-021-03046-3. Online ahead of print.

ABSTRACT

BACKGROUND: Bowel preparation before multiparametric MRI (mpMRI) of the prostate is performed widely, despite contradictory or no evidence for efficacy.

PURPOSE: To investigate the value of hyoscine N-butylbromide (HBB), microenema (ME) and ‘dietary restrictions’ (DR) for artifact reduction and image quality (IQ) in mpMRI of the prostate.

STUDY TYPE: Retrospective.

POPULATION: Between 10/2018 and 02/2020 treatment-naïve men (median age, 64.9; range 39.8-87.3) who underwent mpMRI of the prostate were included. The total patient sample comprised of n = 180 patients, who received either HBB, ME, were instructed to adhere to DR, or received a combination of those measures prior to the MR scan.

FIELD STRENGTH/SEQUENCE: T2-weighted imaging (T2w), diffusion-weighted imaging (DWI), and dynamic contrast-enhanced MRI (DCE-MRI) scanned on two 3T systems.

ASSESSMENT: A radiologist specialized in urogenital imaging (R1) and a senior radiology resident (R2) visually assessed IQ parameters on transversal T2w, DWI and ADC maps on a 5-point Likert-like scale.

STATISTICAL TESTS: Group comparison between IQ parameters was performed on reader level using Kruskal-Wallis and Mann-Whitney U tests. Binary univariate logistic regression analysis was used to assess independent predictors of IQ. Interrater agreement was assessed using Intraclass Correlation Coefficient (ICC).

RESULTS: ‘DWI geometric distortion’ was significantly more pronounced in the HBB+/ME-/DR- (R1, 3.6 and R2, 4.0) as compared to the HBB-/ME+/DR- (R1, 4.2 and R2, 4.6) and HBB+/ME+/DR- (R1, 4.3 and R2, 4.7) cohort, respectively. Parameters ‘DWI IQ’ and ‘Whole MRI IQ’ were rated similarly by both readers. ME was a significant independent predictor of ‘good IQ’ for the whole MRI for R1 [b = 1.09, OR 2.98 (95% CI 1.29, 6.87)] and R2 [b = 1.01, OR 2.73 (95% CI 1.24, 6.04)], respectively.

DATA CONCLUSION: ME seems to significantly improve image quality of DWI and the whole mpMRI image set of the prostate. HBB and DR did not have any benefit.

PMID:33770222 | DOI:10.1007/s00261-021-03046-3

Abdom Radiol (NY). 2021 Mar 26. doi: 10.1007/s00261-021-03055-2. Online ahead of print.

ABSTRACT

PURPOSE: To compare the diagnostic performance of diffusion-weighted imaging (DWI), gradient-recalled echo-based magnetic resonance elastography (GRE-MRE), and spin-echo echo-planar imaging-based MRE (SE-EPI-MRE) in liver fibrosis staging.

METHODS: A systematic literature search was done to collect studies on the performance of DWI, GRE-MRE, and SE-EPI-MRE for diagnosing liver fibrosis. Pooled sensitivity, specificity, diagnostic odds ratio, positive and negative likelihood ratio, and a summary receiver operating characteristic (ROC) curve were estimated with a bivariate random effects model. Subgroup analyses on various study characteristics were performed.

RESULTS: Sixty studies with a total of 6620 patients were included in the meta-analysis. Pooled sensitivity and specificity of GRE-MRE and SE-EPI-MRE showed high diagnostic accuracy and did not differ significantly. The area under the summary ROC curve for all stages of fibrosis differed significantly between DWI (0.83-0.88) and either GRE-MRE (0.95-0.97) or SE-EPI-MRE (0.95-0.99). Substantial heterogeneity was detected for all three imaging methods.

CONCLUSIONS: Both GRE-MRE and SE-EPI-MRE are highly accurate for detection of each liver fibrosis stage, with high potential to replace liver biopsy. Although DWI had a moderate accuracy in distinguishing liver fibrosis, it could be regarded as an alternative to MRE, since it is widely available and easily implemented in routine liver MRI.

PMID:33770223 | DOI:10.1007/s00261-021-03055-2

J Food Prot. 2021 Mar 26. doi: 10.4315/JFP-20-431. Online ahead of print.

ABSTRACT

Spoilage of HTST- (high-temperature, short-time) and vat- pasteurized fluid milk due to introduction of Gram-negative bacteria post-pasteurization remains a challenge for the dairy industry. While processing facility level practices (e.g., sanitation practices) are known to impact the frequency of post-pasteurization contamination (PPC), the relative importance of different practices is not well defined, affecting the ability of facilities to select intervention targets that reduce PPC and provide the greatest return on investment. Thus, the goal of this study was to use an existing longitudinal dataset of bacterial spoilage indicators obtained for pasteurized fluid milk samples collected from 23 processing facilities between July 2015 and November 2017 (with 3 to 5 samplings per facility) and data from a survey on fluid milk quality management practices, to identify factors associated with PPC and rank their relative importance, using two separate approaches: (i) multimodel inference and (ii) conditional random forest. Data pre-processing for multimodel inference analysis showed (i) nearly all factors were significantly associated with PPC when assessed individually using univariable logistic regression and (ii) numerous pairs of factors were strongly associated with each other (Cramer’s V ³0.80). Multimodel inference and conditional random forest analyses identified similar drivers associated with PPC; factors identified as most important based on these analyses included cleaning and sanitation practices, activities related to good manufacturing practices, container type (which is a proxy for different filling equipment), in-house finished product testing, and designation of a quality department, indicating potential targets for reducing PPC. In addition, this study illustrates how machine learning approaches can be used with highly correlated and unbalanced data, as typical for food safety and quality, to facilitate improved data analyses and decision-making.

PMID:33770185 | DOI:10.4315/JFP-20-431

PLoS One. 2021 Mar 26;16(3):e0249295. doi: 10.1371/journal.pone.0249295. eCollection 2021.

ABSTRACT

STUDY DESIGN: Chart reviews were combined with neurological and functional outcome data obtained from the prospective European Multicenter Study on Spinal Cord Injury (EMSCI, www.emsci.org).

OBJECTIVES: To determine if strict physical isolation of multidrug-resistant organisms (MDRO)-positive patients negatively affects neurological recovery and functional outcome in the first year after acute spinal cord injury (SCI).

SETTING: SCI Center Heidelberg University Hospital.

METHODS: Individuals with acute (< 6 weeks) traumatic or ischemic SCI were included. During primary comprehensive care, isolated MDRO-positive patients (n = 13) were compared with a MDRO-negative control group (n = 13) matched for functional (Spinal Cord Independence Measure-SCIM) and neurological impairment (motor scores based on the International Standards for Neurological Classification of Spinal Cord Injury-ISNCSCI) at an early stage up to 40 days after SCI. SCIM scores and motor scores were obtained at 12 weeks (intermediate stage) and 24 or 48 weeks (late stage) after SCI.

RESULTS: Isolated MDRO-positive (median duration of hospitalization: 175 days, 39% of inpatient stay under isolation measures) and non-isolated MDRO-negative (median duration of hospitalization: 161 days) patients showed functional and neurological improvements, which were not statistically different between groups at the intermediate and late stage.

CONCLUSION: Prolonged isolation due to MDRO colonization for over a third of the inpatient comprehensive care period does not appear to impair neurological recovery and functional outcome within the first year after SCI.

PMID:33770131 | DOI:10.1371/journal.pone.0249295

PLoS One. 2021 Mar 26;16(3):e0249213. doi: 10.1371/journal.pone.0249213. eCollection 2021.

ABSTRACT

The aim of this study was to evaluate the influence of increase in intraocular pressure (IOP) and cooccurring changes in ocular biometry parameters on the corneal optical coherence tomography (OCT) speckle distribution in ex-vivo experiments on porcine intact eyes. Twenty-three eyeballs were used in the inflation test where IOP in the anterior chamber was precisely set from 10 mmHg to 40 mmHg in steps of 5 mmHg and where eye biometry was utilized (IOL Master 700). To assess the influence of the duration of the experiment on the OCT speckle statistics, the second experiment was performed with 10 eyeballs at the constant IOP of 15 mmHg. Based on the OCT scans of central cornea (Copernicus REVO), spatial maps of the scale parameter (a) and the shape parameter (v) of the gamma distribution speckle model were estimated. The means of both parameters for each spatial map were computed within the 2 mm of the central stroma. Both distributional parameters statistically significantly varied with IOP and time (one way repeated measures ANOVA, all p-values < 0.001). The a parameter revealed a faster statistically significant increase in IOP up to 25 mmHg, regardless of time. Central corneal thickness (CCT), the anterior chamber depth, and the mean equivalent spherical power varied significantly with IOP, whereas CCT and axial length changed statistically significantly with time. Statistically significant correlation was found between CCT and the a parameter, after removing IOP as a confounding factor (r = -0.576, p < 0.001). The parameters of the gamma distribution can be used not only for identifying IOP induced changes in the optical scattering within the corneal stroma, but also in corneal geometry. The approach of corneal speckle analysis could be potentially utilized for an indirect and noninvasive assessment of some properties of corneal stroma.

PMID:33770135 | DOI:10.1371/journal.pone.0249213

J Clin Endocrinol Metab. 2021 Mar 26:dgab200. doi: 10.1210/clinem/dgab200. Online ahead of print.

ABSTRACT

PURPOSE: Previous epidemiological evidence showed that type 2 diabetes (T2D) is related with gout. However, the causality and the direction of this association are still not definitely elucidated. We aimed to investigate bidirectional associations of T2D and glycemic traits with serum urate concentrations and gout using a Mendelian randomization (MR) approach.

METHODS: Summary statistics from the large-scale genome-wide association studies conducted for T2D (Ncase=62,892, Ncontrol=596,424), fasting glucose (N=133,010), fasting insulin (N=133,010), hemoglobinA1c (N=123,665), homeostasis model assessment of insulin resistance (N=46,186), urate (N=110,347) and gout (Ncase=2,115, Ncontrol=67,259) among participants of European ancestry were analyzed. For each trait of interest, independent genome-wide significant (p<5×10 -8) single nucleotide polymorphisms were selected as instrumental variables. The inverse-variance weighted method was used for the primary analyses.

RESULTS: Genetic predisposition to higher risk of T2D (beta=0.042; 95% CI=0.016-0.068; p=0.002) and higher levels of fasting insulin (beta=0.756; 95% CI=0.408-1.102; p=1.96e-05) were significantly associated with increased serum urate concentrations. Moreover, we found suggestively significant evidence supporting a causal role of fasting insulin on risk of developing gout (OR=3.06; 95% CI=0.88-10.61; p=0.078). In the reverse direction analysis, both genetic predisposition to urate and gout were not associated with T2D and any of four glycemic traits being investigated.

CONCLUSIONS: This study provides supportive evidence on causal associations of T2D and fasting insulin with serum urate concentrations, and suggestive association of fasting insulin with risk of gout. Future research is required to examine the underlying biological mechanisms on such relationships.

PMID:33770169 | DOI:10.1210/clinem/dgab200