1,721,175 research outputs found
Estimating reliability and generalizability from hierarchical biomedical data
No full textIt is shown how hierarchical biomedical data, such as coming from longitudinal clinical trials, meta-analyses, or a combination of both, can be used to provide evidence for quantitative strength of reliability, agreement, generalizability, and related measures that derive from association concepts. When responses are of a continuous, Gaussian type, the linear mixed model is shown to be a versatile framework. At the same time, the framework is embedded in the generalized linear mixed models, such that non-Gaussian, e.g., binary, outcomes can be studied as well. Similarities and, above all, important differences are studied. All developments are exemplified using clinical studies in schizophrenia, with focus on the endpoints Clinician's Global Impression (CGI) or Positive and Negative Syndrome Scale (PANSS).status: Publishe
A family of measures to evaluate scale reliability in a longitudinal setting
No full textThe concept of reliability denotes one of the most important psychometric properties of a measurement scale. Reliability refers to the capacity of the scale to discriminate between subjects in a given population. In classical test theory, it is often estimated by using the intraclass correlation coefficient based on two replicate measurements. However, the modelling framework that is used in this theory is often too narrow when applied in practical situations. Generalizability theory has extended reliability theory to a much broader framework but is confronted with some limitations when applied in a longitudinal setting. We explore how the definition of reliability can be generalized to a setting where subjects are measured repeatedly over time. On the basis of four defining properties for the concept of reliability, we propose a family of reliability measures which circumscribes the area in which reliability measures should be sought. It is shown how different members assess different aspects of the problem and that the reliability of the instrument can depend on the way that it is used. The methodology is motivated by and illustrated on data from a clinical study on schizophrenia. On the basis of this study, we estimate and compare the reliabilities of two different rating scales to evaluate the severity of the disorder. Copyright (c) 2009 Royal Statistical Society.
A Five-Year Computed Tomography Follow-up Study of Proximal Aortic Neck Dilatation After Endovascular Aortic Repair Using Four Contemporary Types of Endograft Reply
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Introduction of a New Pathology Workup Protocol for Glottic Cancer Treated With Transoral Laser Microsurgery (TLM): Prospective Analysis of Oncological Outcomes and Matched Case-Control Study
No full textBACKGROUND/PURPOSE: The value of margin status after TLM for glottic cancer is debatable, due to difficulties in specimen orientation and margin analysis. To reduce these difficulties, we recently introduced a standardized protocol of oriented fixation of TLM specimens. This proved feasible and resulted in high margin evaluability rates and a decreased rate of false positive deep margins, when compared to a historical TLM cohort. For the patients whose specimens were processed according to this protocol, we prospectively analyzed oncological outcomes, identified prognostic factors and assessed the influence of the protocol introduction on outcomes compared with a historical TLM cohort. METHODS: Ninety-six patients with glottic malignancies treated with TLM were included. Resection specimens were processed according to the new protocol. Descriptive statistics and survival analyses were used to determine oncological outcomes. To assess the effect of the protocol introduction on outcomes, a matched-case-control analysis was performed, using a historical TLM-cohort as controls. The Cox proportional hazards model was used to analyze prognostic effects of patient and treatment characteristics, including the pathology protocol introduction, on overall survival (OS), disease-specific survival (DSS), disease-free survival (DFS) and local recurrence-free survival (LRFS). RESULTS: Two-year outcomes were favorable: 88.5% OS, 97.0% DSS, and 87.6% LRFS. At multivariable analysis, the presence of multiple positive superficial margins was a negative prognosticator for OS (HR 4.102) and increasing cT classification proved a negative prognosticator for DFS (HR 2.828) and LRFS (HR 2.676). Matched case-control analysis did not reveal a significant difference in oncological outcomes between cohorts. Deep margin status had a strong differential effect for DFS (p-value for interaction = 0.0205) and for LRFS (p-value for interaction = 0.0176) between cohorts, indicating a prognostic effect of deep margin status on both outcomes in the current cohort, but not in the historical cohort. DISCUSSION/CONCLUSION: The introduction of a new standardized technique of oriented fixation of TLM specimens did not affect oncological outcomes when compared to a historical TLM cohort, but assigned a significant prognostic effect to deep margin status for DFS and LRFS, facilitating the decision making process with regards to planning of second-look procedures, administration of adjuvant radiotherapy or determination of follow-up intensity.sponsorship: Costs related to statistical analysis and manuscript publication were funded through the Vandeputte Walter Hoofd-Halskanker fund of the KU Leuven. (Vandeputte Walter Hoofd-Halskanker fund of the KU Leuven)status: Publishe
Long-term outcome and pre-interventional predictors for late intervention after uterine fibroid embolization
No full textOBJECTIVES: To assess the long-term freedom of surgical conversion after uterine fibroid embolization (UFE) and to define predictors for better clinical outcome. Additionally, the potential of pregnancy after UFE is assessed. STUDY DESIGN: Single-center retrospective cohort study including 190 patients who underwent UFE between 2001 and 2016. Data were obtained by postal questionnaire including symptom severity, late reintervention rate and post procedural fertility. Patient characteristics were extracted from the patients' electronic medical records. The cumulative rate of freedom from treatment failure was determined by Kaplan-Meier analysis. Cox regression models were used for univariate analyses of the association between patient preinterventional characteristics and late surgical conversion. Secondary outcome measures were patient specific predictors of treatment failure and evaluation of post-procedural fertility. RESULTS: Long-term follow-up was available for a median of 6.1 years (range 1.2-15.2 y) in 95 out of 190 patients (50 %). Freedom from treatment failure showed a cumulative rate of 72.9 % after 10 years and stable until end of follow-up. A 63.8 % reduction in symptoms and a 23.3% increase in quality of life was found. Significant increase of treatment failure was found in patients with increasing pre-interventional uterine volume (p = 0.0003) or dominant fibroid volume (p = 0.0042); 9 out of 23 patients (39.13 %) with child-bearing wish became pregnant and conceived one or more children after UFE. CONCLUSION: UFE is associated with sustained long-term symptom control. Larger size uterus or dominant fibroma are correlated with higher late surgical conversion rate. Last, women can become pregnant and deliver after UFE.status: Publishe
Plasma Iron Levels at Early Breast Cancer Diagnosis Are Associated With Development of Secondary Metastases: A Single-Center Retrospective Cohort Study
No full textBackground: Breast cancer is the most common malignancy in women and the leading cause of cancer-related death. Although most early-stage patients are cured, 20% to 30% develop metastases, significantly reducing survival rates. Recent research highlights the role of iron in cancer progression, although its full impact on breast cancer metastasis is not yet fully understood.Objectives: The aim of this study is to investigate the association between plasma iron levels at diagnosis of early-stage breast cancer and the risk of developing metastatic disease.Design: Retrospective single-center study.Methods: Patients with stage I to III breast cancer, diagnosed between 2007 and 2017, and with serum iron, transferrin saturation, and ferritin values available within 1.5 months before or after diagnosis were included. Cox proportional hazard models were applied to determine the association between iron levels and risk of metastasis.Results: In total, 1113 patients were included, 10% of them developed distant metastasis over a median follow-up period of 7 years. In multivariable analysis adjusting for age, stage, and subtype, transferrin saturation and serum iron were significantly associated with an increased risk of breast cancer metastasis. For each 10% increment of transferrin saturation at baseline, there was a 19% increase in metastatic risk (hazard ratio [HR] = 1.19; 95% confidence interval [CI] = [1.02-1.38]). Similarly, a serum iron increment of 10 mu g/dL led to a 6% increase in risk (HR = 1.06; 95% CI = [1.01-1.12]). Ferritin was found not to be associated with metastatic risk (HR = 0.99; 95% CI = [0.98, 1.01]). There was no significant association with metastatic site or breast cancer subtype when adjusting for age and stage.Conclusion: Elevated transferrin saturation and serum iron at early breast cancer diagnosis are associated with increased risk for metastatic disease but not with location of metastases or breast cancer subtype. Further research is needed to understand the underlying mechanisms and to explore the potential of iron-targeted therapies.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: SMF acknowledges KU Leuven C1 funding and funding from the ERC under Proof of Concept grant agreement no. 101112780—MetaIron. All other authors declare that no funds, grants, or other support was received during the preparation of this article
Overall survival and factors predicting long-term outcome after thoracic aortic endovascular repair
No full textPURPOSES: To assess overall survival and to determine factors predicting outcome after thoracic endovascular aortic repair. MATERIALS AND METHODS: A Retrospective analysis was performed on a cohort of 212 consecutive patients (165 men and 47 women; mean age 64 years) who underwent thoracic endovascular aortic repair in a tertiary referral center for aortic disease. Main indications were true thoracic aortic aneurysm (n = 58; 27.6%), traumatic aortic rupture (n = 33; 15.7%), anastomotic pseudoaneurysms (n = 23; 10.9%), chronic type B aortic dissection (n = 22; 10.5%), and symptomatic, acute type B dissection (n = 21; 10.0%). In 79 patients (37.3%), a hybrid procedure, including supra-aortic rerouting, was performed. Kaplan-Meier estimates were used for overall survival and Cox regression models were used for univariable analysis of the association between risk factors and survival. RESULTS: Proximal landing zones were predominantly zone 3 (n = 66; 31.3%), zone 2 (n = 63; 29.9%), and zone 1 (n = 38; 18%). In-hospital mortality was n = 18 (8.5%). Overall survival was 79.6%, 65.9%, and 51.1% at 2, 5, and 10 years, respectively; better overall survival was shown for traumatic aortic rupture, anastomotic pseudoaneurysms, and chronic posttraumatic pseudoaneurysms (p < 0.05). Clinical risk factors influencing overall survival include prior coronary bypass surgery, atrial flutter, arterial hypertension, renal failure, chronic obstructive pulmonary disease, and associated abdominal aortic aneurysm (p < 0.05). CONCLUSIONS: Thoracic endovascular aortic repair is an effective treatment option for various thoracic aortic diseases with highest survival rates for traumatic aortic rupture and anastomotic pseudoaneurysms. Several clinical parameters are identified as risk factors for overall survival.status: Publishe
Elevated CA 15.3 in Newly Diagnosed Breast Cancer: A Retrospective Study
No full textPURPOSE: To examine the relationship between baseline elevated CA 15.3 (>30 kU/L) and the prevalence of primary or secondary metastatic disease in breast cancer. METHODS: We performed a retrospective, single-center cohort study on patients with newly diagnosed breast cancer and baseline CA 15.3> 30 kU/L, diagnosed between 2000-2015. Information on tumor characteristics, pre-treatment CA 15.3, staging results, treatment approach, disease recurrence and death were collected from individual medical files. For every tumor subtype, the optimal cut-off value of CA 15.3 for determining primary metastatic disease is determined. RESULTS: Eight hundred ninety-four patients with baseline CA15.3 > 30 kU/L were included of which 38% were diagnosed with primary metastatic disease while 15% subsequently developed secondary metastatic disease, with a median follow-up of 74 months. LuminalHER2 tumors had the highest proportion of primary metastatic disease (48%), Triple Negative tumors had the highest proportion of secondary metastatic disease (24%) (p=0.008). A higher CA 15.3 value corresponds to higher risk of both primary and secondary metastatic disease (p30 kU/L, 38% presents with primary metastatic disease and 15% develops secondary metastatic disease, with a median follow-up of 74 months. Our results can help clinicians to identify patients at risk of primary or secondary metastatic disease via information on tumor subtype and baseline CA 15.3.sponsorship: This trial was approved by the Research Ethics Committee UZ/KU Leuven (reference number MP012727) , in compliance with the principles of the Helsinki Declaration. The authors would like to thank C. Remmerie for her contri- bution in collecting the data, dr. S.Han and K. Vantornout for adding information on pregnancy to our data and the Belgian Cancer Registry for providing data on breast cancer mortality rates in Belgium. (MP012727)status: Publishe
Safety and efficacy of embolotherapy for severe hemorrhage after partial nephrectomy
No full textBackground : Partial nephrectomy may be complicated by postoperative hemorrhage, which may be treated by transcatheter embolization
Purpose : To assess the safety and efficacy of embolotherapy for hemorrhagic complications of partial nephrectomy and to analyze the potential correlation between multiple bleeding sites on angiography and surgical complexity
Material and Methods : A cohort of 25 patients presenting with severe, postoperative bleeding after partial nephrectomy and treated with catheter-directed superselective embolization was included. Patients' demographics, radiological investigations before the embolization, and clinical outcome after embolization were analyzed. Mann-Whitney U test was used to analyze the potential difference in the RENAL score between patients with one or more bleeding sites in the resection area.
Results : Selective renal angiography revealed multiple bleeding sites at the resection bed in 8 (32%) patients with amorphous contrast extravasation in 10 (40%) patients. Embolization with use of a microcatheter and microcoils was effective to stop the bleeding in all but one patient, the latter requiring a second embolization two days later. Transient decrease in renal function was noted in 3/25 (12%) patients with full recovery in two of the three. Patients with multiple bleeding sites did not show significantly different RENAL scores compared to patients with a single bleeding site (P = 0.148).
Conclusion : Embolotherapy for postoperative partial nephrectomy-related bleeding is safe and effective with a low rate of recurrent bleeding. The number of bleeding sites at the resection area did not correlate to the RENAL score.Maleux, G (reprint author), Univ Hosp Leuven, Dept Radiol, Herestr 49, B-3000 Leuven, Belgium.
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