Calibration plots for risk prediction models in the presence of competing risks

A predicted risk of 17% can be called reliable if it can be expected that the event will occur to about 17 of 100 patients who all received a predicted risk of 17%. Statistical models can predict the absolute risk of an event such as cardiovascular death in the presence of competing risks such as death due to other causes. For personalized medicine and patient counseling, it is necessary to check that the model is calibrated in the sense that it provides reliable predictions for all subjects. There are three often encountered practical problems when the aim is to display or test if a risk prediction model is well calibrated. The first is lack of independent validation data, the second is right censoring, and the third is that when the risk scale is continuous, the estimation problem is as difficult as density estimation. To deal with these problems, we propose to estimate calibration curves for competing risks models based on jackknife pseudo‐values that are combined with a nearest neighborhood smoother and a cross‐validation approach to deal with all three problems. Copyright © 2014 John Wiley & Sons, Ltd.     

Testosterone Levels Are Decreased and Associated with Disease Duration in Male Spinocerebellar Ataxia Type 2 Patients

The Cerebellum - Spinocerebellar ataxia type 2 (SCA2) is a progressive neurodegenerative disorder due to an unstable expansion of a CAG repeat in the ATXN2 gene. Despite clinical and experimental...     

Ruxolitinib versus best available therapy in patients with polycythemia vera: 80-week follow-up from the RESPONSE trial

RESPONSE is an open-label phase 3 study evaluating the Janus kinase 1/Janus kinase 2 inhibitor ruxolitinib versus best available therapy for efficacy/safety in hydroxyurea-resistant or intolerant patients with polycythemia vera. This preplanned analysis occurred when all patients completed the Week 80 visit or discontinued. Objectives included evaluating the durability of the primary response (Week 32 phlebotomy-independent hematocrit control plus ≥35% spleen volume reduction), its components, and that of complete hematologic remission; and long-term safety. Median exposure was 111 weeks; 91/110 (82.7%) patients randomized to ruxolitinib remained on treatment. No patients continued best available therapy (98/112 [87.5%] crossed over to ruxolitinib, most at/soon after Week 32). At Week 32, primary response was achieved by 22.7% vs. 0.9% of patients randomized to ruxolitinib and best available therapy, respectively (hematocrit control, 60.0% vs. 18.8%; spleen response, 40.0% vs. 0.9%). The probability of maintaining primary and hematocrit responses for ≥80 weeks was 92% and 89%, respectively; 43/44 spleen responses were maintained until Week 80. Complete hematologic remission at Week 32 was achieved in 23.6% of ruxolitinib-randomized patients; the probability of maintaining complete hematologic remission for ≥80 weeks was 69%. Among ruxolitinib crossover patients, 79.2% were not phlebotomized, and 18.8% achieved a ≥35% reduction from baseline in spleen volume after 32 weeks of treatment. New or worsening hematologic laboratory abnormalities in ruxolitinib-treated patients were primarily grade 1/2 decreases in hemoglobin, lymphocytes, and platelets. The thromboembolic event rate per 100 patient-years was 1.8 with randomized ruxolitinib treatment vs. 8.2 with best available therapy. These data support ruxolitinib as an effective long-term treatment option for hydroxyurea-resistant or intolerant patients with polycythemia vera. This trial was registered at clinicaltrials.gov identifier: 01243944.     

A Nomogram for Predicting the Likelihood of Additional Nodal Metastases in Breast Cancer Patients With a Positive Sentinel Node Biopsy

Background:The standard of care for breast cancer patients with sentinel lymph node (SLN) metastases includes complete axillary lymph node dissection (ALND). However, many question the need for complete ALND in every patient with detectable SLN metastases, particularly those perceived to have a low risk of non-SLN metastases. Accurate estimates of the likelihood of additional disease in the axilla could assist greatly in decision-making regarding further treatment.Methods:Pathological features of the primary tumor and SLN metastases of 702 patients who underwent complete ALND were assessed with multivariable logistic regression to predict the presence of additional disease in the non-SLNs of these patients. A nomogram was created using pathological size, tumor type and nuclear grade, lymphovascular invasion, multifocality, and estrogen-receptor status of the primary tumor; method of detection of SLN metastases; number of positive SLNs; and number of negative SLNs. The model was subsequently applied prospectively to 373 patients.Results:The nomogram for the retrospective population was accurate and discriminating, with an area under the receiver operating characteristic (ROC) curve of 0.76. When applied to the prospective group, the model accurately predicted likelihood of non-SLN disease (ROC, 0.77).Conclusions:We have developed a user-friendly nomogram that uses information commonly available to the surgeon to easily and accurately calculate the likelihood of having additional, non-SLN metastases for an individual patient.Drs. Manasseh and Bevilacqua contributed equally to the work.Dr. Bevilacqua is currently affiliated with Hospital Sírio Libanes, Instituto Brasileiro de Controle do Câncer, and Disciplina de Cirurgia Geral, Departamento de Cirurgia, Faculdade de Medicina da Univerdidade de Sao Paulo. São Paulo, Brazil; Dr. Boolbol is currently affiliated with Beth Israel Medical Center, New York, New York.     

Cytochrome P450 3A polymorphisms and immunosuppressive drugs

With the use of powerful immunosuppressive drugs, organ transplantation has become the treatment of choice for many cases of end-stage chronic organ failure. The calcineurin inhibitors, cyclosporine and tacrolimus, which are the backbone of current immunosuppressive regimens, may be difficult to use because of the large interindividual variability of their pharmacokinetic characteristics and a narrow therapeutic index. Since cytochrome P450 (CYP) 3A4 and CYP3A5 are both involved in their metabolism, the consequences of the polymorphism of these enzymes were studied. It has been recently shown that the CYP3A5*3 polymorphism is associated with both the pharmacokinetics and pharmacodynamic consequences of tacrolimus. The association between the CYP3A4 and CYP3A5 polymorphisms and cyclosporine pharmacokinetics is more questionable. It is important to test these initial results prospectively to improve the individualized use of these drugs.     

Effects of dobutamine on systemic, regional and microcirculatory perfusion parameters in septic shock: a randomized, placebo-controlled, double-blind, crossover study

Purpose

The role of dobutamine during septic shock resuscitation is still controversial since most clinical studies have been uncontrolled and no physiological study has unequivocally demonstrated a beneficial effect on tissue perfusion. Our objective was to determine the potential benefits of dobutamine on hemodynamic, metabolic, peripheral, hepatosplanchnic and microcirculatory perfusion parameters during early septic shock resuscitation.

Methods

We designed a randomized, controlled, double-blind, crossover study comparing the effects of 2.5-h infusion of dobutamine (5 mcg/kg/min fixed-dose) or placebo in 20 septic shock patients with cardiac index ≥2.5 l/min/m² and hyperlactatemia. Primary outcome was sublingual perfused microvascular density.

Results

Despite an increasing cardiac index, heart rate and left ventricular ejection fraction, dobutamine had no effect on sublingual perfused vessel density [9.0 (7.9–10.1) vs. 9.1 n/mm (7.9–9.9); p = 0.24] or microvascular flow index [2.1 (1.8–2.5) vs. 2.1 (1.9–2.5); p = 0.73] compared to placebo. No differences between dobutamine and placebo were found for the lactate levels, mixed venous-arterial pCO₂ gradient, thenar muscle oxygen saturation, capillary refill time or gastric-to-arterial pCO₂ gradient. The indocyanine green plasma disappearance rate [14.4 (9.5–25.6) vs. 18.8 %/min (11.7–24.6); p = 0.03] and the recovery slope of thenar muscle oxygen saturation after a vascular occlusion test [2.1 (1.1–3.1) vs. 2.5 %/s (1.2–3.4); p = 0.01] were worse with dobutamine compared to placebo.

Conclusions

Dobutamine failed to improve sublingual microcirculatory, metabolic, hepatosplanchnic or peripheral perfusion parameters despite inducing a significant increase in systemic hemodynamic variables in septic shock patients without low cardiac output but with persistent hypoperfusion.