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The concordance correlation coefficient (CCC) is a common tool to assess agreement among multiple observers for continuous and discrete responses. However, previous results in the statistical literature have shown that the CCC estimators may suffer from a bias problem under a misspecified model for normal data. In order to avoid fitting data with a misspecified model, thus yielding biased CCC estimates for longitudinal overdispersed Poisson data, this research proposes new model-averaged estimators of CCC by combining the estimators of the variance components (VC) approach with model selection via corrected conditional Akaike information criterion (CAICC) and corrected conditional Bayesian information criterion (CBICC) measures under extended overdispersed three-way Poisson mixed-effects models. In simulation studies, the performance of the proposed model-averaged estimators is compared with the VC estimators with and without model selection via CAICC and CBICC and other existing model-averaged estimators for longitudinal Poisson and overdispersed Poisson data sets. An application of corticospinal diffusion tensor tractography study is presented for illustration. It can be concluded that the proposed model-averaged approach is a reliable procedure yielding small mean square errors and nominal 95% coverage rates. Therefore, the new model-averaged estimator is more robust to model misspecification than other competitors. [ABSTRACT FROM AUTHOR]

Background: Hemorrhoidectomy is associated with postoperative pain and prolonged wound healing. Glyceryl trinitrate has been shown to decrease muscle spasm and increase anodermal blood flow. A meta-analysis of randomized controlled trials was conducted to evaluate the efficacy of topical glyceryl trinitrate application in pain relief after hemorrhoidectomy. Methods: PubMed, EMBASE, Cochrane Library, Scopus, and ClinicalTrials.gov registries were searched for studies published before August 2015. Individual effect sizes were standardized, and a meta-analysis was conducted to calculate a pooled effect size using random effects models. Pain was assessed using a visual analog scale on days 1, 3, 7, and 14 after operation. Secondary outcomes included time taken to resume routine activities, wound healing at 3 weeks after operation, complication, and headache incidence. Results: A total of 12 trials with 1095 patients were reviewed. Significant pain reduction was observed on days 1, 3, 7, and 14 after hemorrhoidectomy in the glyceryl trinitrate groups. Glyceryl trinitrate-treated patients appeared to resume routine activities earlier than those in the control group (weight mean difference −7.52; 95 % confidence interval: 16.13-1.08). The wound healing rates 3 weeks after operation were significant higher in the glyceryl trinitrate-treated groups than in the control group (risk ratio 1.79; 95 % confidence interval: 1.38-2.33). However, the incidence of headache significantly increased in the glyceryl trinitrate group (risk ratio 3.68; 95 % confidence interval: 1.62-8.34). Conclusion: Topical application of glyceryl trinitrate effectively relieves pain and promotes wound healing after hemorrhoidectomy; however, the substantial headache incidence may limit extensive application. [ABSTRACT FROM AUTHOR]

For longitudinal overdispersed Poisson data sets, estimators of the intra-, inter-, and total concordance correlation coefficient through variance components have been proposed. However, biased estimators of quadratic forms are used in concordance correlation coefficient estimation. In addition, the generalized estimating equations approach has been used in estimating agreement for longitudinal normal data and not for longitudinal overdispersed Poisson data. Therefore, this paper proposes a modified variance component approach to develop the unbiased estimators of the concordance correlation coefficient for longitudinal overdispersed Poisson data. Further, the indices of intra-, inter-, and total agreement through generalized estimating equations are also developed considering the correlation structure of longitudinal count repeated measurements. Simulation studies are conducted to compare the performance of the modified variance component and generalized estimating equation approaches for longitudinal Poisson and overdispersed Poisson data sets. An application of corticospinal diffusion tensor tractography study is used for illustration. In conclusion, the modified variance component approach performs outstandingly well with small mean square errors and nominal 95% coverage rates. The generalized estimating equation approach provides in model assumption flexibility of correlation structures for repeated measurements to produce satisfactory concordance correlation coefficient estimation results. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: The reproducibility of corticospinal diffusion tensor tractography (DTT) for a guideline is important before longitudinal monitoring of the therapy effects in stroke patients. This study aimed to establish the reproducibility of corticospinal DTT indices in healthy subjects and chronic hemiparetic stroke patients. Materials and methods: Written informed consents were obtained from 10 healthy subjects (mean age 25.8±6.8 years), who underwent two scans in one session plus the third scan one week later, and from 15 patients (mean age 47.5±9.1 years, 6–60 months after the onset of stroke, NIHSS scores between 9 and 20) who were scanned thrice on separate days within one month. Diffusion-tensor imaging was performed at 3T with 25 diffusion directions. Corticospinal tracts were reconstructed using fiber assignment by continuous tracking without and with motion/eddy-current corrections. Intra- and inter-rater as well as intra- and inter-session variations of the DTT derived indices (fiber number, apparent diffusion coefficient (ADC), and fractional anisotropy (FA)) were assessed. Results: Intra-session and inter-session coefficients of variations (CVs) are small for FA (1.13–2.09%) and ADC (0.45–1.64%), but much larger for fiber number (8.05–22.4%). Inter-session CVs in the stroke side of patients (22.4%) are higher than those in the normal sides (18.0%) and in the normal subjects (14.7%). Motion/eddy-current correction improved inter-session reproducibility only for the fiber number of the infarcted corticospinal tract (CV reduced from 22.4% to 14.1%). Conclusion: The fiber number derived from corticospinal DTT shows substantially lower precision than ADC and FA, with infarcted tracts showing lower reproducibility than the healthy tissues. [ABSTRACT FROM AUTHOR]

Background: Our study investigated the diagnostic value of the mineralization findings and high-density secretion features of sinus computed tomography (CT) images in cases of chronic rhinosinusitis (CRS) compared to histopathology and operative findings. Methods: This was a prospective cohort study of 193 patients consecutively enrolled for endoscopic sinus surgery (ESS). Group 1 had mineralization in the sinus; group 2 had high-density secretions in the sinus but no mineralization; group 3 lacked both high-density secretions and evidence of mineralization. Intergroup comparisons were performed for histopathology (especially presence of fungus ball), CT scores, and gross operative appearance. Results: Histopathologic evidence of fungus ball (FB) compared to presence of CT findings was significantly different between the groups, with the following percentages of patients demonstrating FB presence: 33% of group 1 (CT mineralization) (n = 48); 4% of group 2 (CT hyperdensity) patients (n = 25); and 2% of group 3 (no mineralization, no hyperdensity) patients (n = 120) (p < 0.05). Operative findings did not necessarily correlate with CT findings and all groups demonstrated varying amounts of dry cheesy (DCM) or wet clay-like (WCLM) material, though this was slightly higher in groups 1 and 2. Conclusion: A preoperative survey of sinus mineralization and high-density secretion features observed with CT was predictive of operative findings and histopathological results indicating a sinus FB. [ABSTRACT FROM AUTHOR]