Search PubMed⌕ Search

Biomedical subjects

M Fiocco

Publications and source records attributed to M Fiocco.

9 recordsLinked to original sources
PubMed2007

Tutorial in biostatistics: competing risks and multi-state models.

Standard survival data measure the time span from some time origin until the occurrence of one type of event. If several types of events occur, a model describing progression to each of these competing risks is needed. Multi-state models generalize competing risks models by also describing transitions to intermediate events. Methods to analyze such models have been developed over the last two decades. Fortunately, most of the analyzes can be performed within the standard statistical packages, but may require some extra effort with respect to data preparation and programming. This tutorial aims to review statistical methods for the analysis of competing risks and multi-state models. Although some conceptual issues are covered, the emphasis is on practical issues like data preparation, estimation of the effect of covariates, and estimation of cumulative incidence functions and state and transition probabilities. Examples of analysis with standard software are shown.

Biometry↗
PubMed2005

Reduced rank proportional hazards model for competing risks.

Competing events concerning individual subjects are of interest in many medical studies. For example, leukemia-free patients surviving a bone marrow transplant are at risk of developing acute or chronic graft-versus-host disease, or they might develop infections. In this situation, competing risks models provide a natural framework to describe the disease. When incorporating covariates influencing the transition intensities, an obvious approach is to use Cox's proportional hazards model for each of the transitions separately. A practical problem then is how to deal with the abundance of regression parameters. Our objective is to describe the competing risks model in fewer parameters, both in order to avoid imprecise estimation in transitions with rare events and in order to facilitate interpretation of these estimates. Suppose that the regression parameters are gathered into a p x K matrix B, with p and K as the number of covariates and transitions, respectively. We propose the use of reduced rank models, where B is required to be of lower rank R, smaller than both p and K. One way to achieve this is to write B = AGamma(intercal) with A and Gamma matrices of dimensions p x R and K x R, respectively. We shall outline an algorithm to obtain estimates and their standard errors in a reduced rank proportional hazards model for competing risks and illustrate the approach on a competing risks model applied to 8966 leukemia patients from the European Group for Blood and Marrow Transplantation.

Biometry↗
PubMed1998

Acute effects of bilateral lung volume reduction surgery on lung and chest wall mechanical properties.

STUDY OBJECTIVES: To characterize acute changes in the dynamic, passive mechanical properties of the lungs and chest wall, elastance (E) and resistance (R), caused by lung volume reduction surgery (LVRS). DESIGN: Prospective data collection. PATIENTS: Nine anesthetized/paralyzed patients with severe emphysema. INTERVENTIONS: Bilateral LVRS. MEASUREMENTS AND RESULTS: From measurements of airway and esophageal pressures and flow during mechanical ventilation throughout the physiologic range of breathing frequency (f) and tidal volume (VT), E and R of the total respiratory system (Ers and Rrs), lungs (EL and RL), and chest wall (Ecw and Rcw) immediately before and after LVRS were calculated. After surgery, Ers, EL, Rrs, and RL were all greatly increased at each combination off and VT (p<0.05). Ecw and Rcw showed no consistent changes (p>0.05). The increases in EL were greatest in those patients with the lowest residual volumes, highest FEV1 values, and highest maximum voluntary ventilations measured 3 months preoperatively (p<0.05); the increases in RL were greatest in those patients with the lowest preoperative residual volumes (p<0.05). The largest increases in RL were in those patients with the largest decreases in residual volume and total lung capacity, measured 3 months postoperatively, caused by LVRS (p<0.05). CONCLUSION: Acute effects of LVRS are large increases in lung elastic tension and resistance; these increases need to be considered in immediate postoperative care, and can be predicted roughly from results of preoperative pulmonary function tests.

Aged↗
PubMed1997

The management of malignant pleural and pericardial effusions.

Malignant pleural and pericardial effusions are debilitating complications of metastatic malignancy. Improper management may lead to multiple hospital admissions and loss of quality of life for patients with a short life expectancy. The majority of malignant pleural effusions are diagnosed and controlled by thoracentesis and sclerosis. Those with pericardial malignancy are best diagnosed and treated with pericardiocentesis and pericardial window. Strategies for the management of more difficult cases are also discussed in this article.

Female↗
PubMed1995

Thoracoscopic pericardiectomy.

A new technique for pericardial resection is described using thoracoscopy. With the advent of newer videolaparoscopic techniques allowing better visualization and the use of new endoscopic staplers, a whole spectrum of surgical procedures can now be performed through the thoracoscope.

Humans↗
PubMed1992

Thoracoscopic lymph node dissection in the staging of esophageal carcinoma.

Preoperative staging in esophageal cancer is usually done by noninvasive tests. Currently, in the staging of lung cancer, when lymph nodes are identified preoperatively by CT or MRI to be greater than 1 cm, surgical staging using mediastinoscopy, Chamberlain procedures, or thoracoscopy are employed. We describe herein the use of thoracoscopy in routine preoperative staging of esophageal cancer. With the advent of newer laparoscopic techniques currently available, thoracoscopy plays an increasing role in the management of intrathoracic disease. Staging thoracoscopy as a routine preoperative invasive staging test appears to be a good diagnostic test.

Carcinoma, Squamous Cell↗