A Stochastic EM Algorithm for G-RHO Family Accelerated Failure Time Model With Random Effects

We propose an accelerated failure time model with random effects for correlated or clustered survival time data. We assume that the error distribution belongs to the family of G-rho distribution and random effects follow multivariate normal distribution. The G-rho family distribution allows us to model ``attenuating'' or ``converging'' hazard functions over time, which represent a type of non-proportional hazards, with the special case of rho=1 corresponding to the proportional odds model. In G-rho family distribution, the larger the value of rho the higher the degree of non-proportionality in the data. Thus, estimating rho as a regression parameter instead of assuming a priori fixed value allows us more flexibility handling many different types of non-proportional converging hazards occurring in practice. We utilize EM algorithm for estimation. More specifically, Stochastic Expectation-Maximization (StEM) algorithm is used to maximize the complete data log-likelihood in the presence of random effects. The conditional expectation in the classical E-step is replaced by a stochastic draw from the posterior distribution of the latent variable via Gibbs sampler method. The computational complexity of the likelihood then can be avoided by maximizing the pseudo-complete data. We also examine the robustness of the estimated fixed effects and the estimated variance components when the error distribution or distribution of the random effects is misspecified through simulation studies, followed by an application to a clinical trial dataset. Public health significance: The proposed method enables researchers 1) to model dependent or clustered survival data which arise frequently in medical research; for example, in familial studies or multi-center clinical trials. 2) to model attenuating hazards which is a type of non-proportional hazard. 3) to reduce bias in estimating treatment effects in the presence of non-proportional hazards and unobserved heterogeneity. The proposed method contributes to more accurate estimation of important covariate effects (such as treatment effects) in practical settings such as in randomized clinical trial

Impact of Antithrombotic Regimen on Mortality, Ischemic, and Bleeding Outcomes after Transcatheter Aortic Valve Replacement

Introduction: Optimal antithrombotic therapy after transcatheter aortic valve replacement (TAVR) remains unclear. We evaluated the association between antithrombotic regimens and outcomes in TAVR patients. Methods: We retrospectively analyzed consecutive patients who underwent TAVR at a single academic center from April 2009 to March 2014. Antithrombotic regimens were classified as single or dual antiplatelet therapy (AP), single antiplatelet plus anticoagulant (SAC), or triple therapy (TT). The primary endpoint was a composite of death, myocardial infarction (MI), stroke, and major bleeding. Adjusted hazard ratios (HRs) were obtained with best subset variable selection methods using bootstrap resampling. Results: Of 246 patients who underwent TAVR, 241 were eligible for analysis with 133, 88, and 20 patients in the AP, SAC, and TT groups, respectively. During a median 2.1-year follow-up, 53.5% had at least one endpoint—the most common was death (68%), followed by major bleeding (23%), stroke (6%), and MI (3%). At 2 years, the composite outcome occurred in 70% of TT, 42% of SAC, and 31% of AP patients. Compared to AP, adjusted HRs for the composite outcome were 2.88 [95% Confidence intervals (CI) (1.61–5.16); p = 0.0004] and 1.66 (95% CI [1.13-2.42]; p = 0.009) in the TT and SAC groups, respectively. Mortality rates at 2 years were 61% in the TT, 32% in the SAC, and 26% in the AP groups (p = 0.005). Conclusions: The risk of the composite outcome of death, MI, stroke, or major bleeding at 2-year follow-up was significantly higher in TAVR patients treated with TT or SAC versus AP, even after multivariate adjustment

Reduction in Total Cardiovascular Events With Ezetimibe/Simvastatin Post-Acute Coronary Syndrome The IMPROVE-IT Trial

AbstractBackgroundIntensive low-density lipoprotein cholesterol therapy with ezetimibe/simvastatin in IMPROVE-IT (IMProved Reduction of Outcomes: Vytorin Efficacy International Trial) significantly reduced the first primary endpoint (PEP) in patients post-acute coronary syndrome (ACS) compared to placebo/simvastatin.ObjectivesThis analysis tested the hypothesis that total events, including those beyond the first event, would also be reduced with ezetimibe/simvastatin therapy.MethodsAll PEP events (cardiovascular [CV] death, myocardial infarction [MI], stroke, unstable angina [UA] leading to hospitalization, coronary revascularization ≥30 days post-randomization) during a median 6-year follow-up were analyzed in patients randomized to receive ezetimibe/simvastatin or placebo/simvastatin in IMPROVE-IT. Negative binomial regression was used for the primary analysis.ResultsAmong 18,144 patients, there were 9,545 total PEP events (56% were first events and 44% subsequent events). Total PEP events were significantly reduced by 9% with ezetimibe/simvastatin vs placebo/simvastatin (incidence-rate ratio [RR]: 0.91; 95% confidence interval [CI]: 0.85 to 0.97; p = 0.007), as were the 3 pre-specified secondary composite endpoints and the exploratory composite endpoint of CV death, MI, or stroke (RR: 0.88; 95% CI: 0.81 to 0.96; p = 0.002). The reduction in total events was driven by decreases in total nonfatal MI (RR: 0.87; 95% CI: 0.79 to 0.96; p = 0.004) and total NF stroke (RR: 0.77; 95% CI: 0.65 to 0.93; p = 0.005).ConclusionsLipid-lowering therapy with ezetimibe plus simvastatin improved clinical outcomes. Reductions in total PEP events, driven by reductions in MI and stroke, more than doubled the number of events prevented compared with examining only the first event. These data support continuation of intensive combination lipid-lowering therapy after an initial CV event. (IMProved Reduction of Outcomes: Vytorin Efficacy International Trial [IMPROVE-IT]; NCT00202878

The epidemiology of dengue outbreaks in 2016 and 2017 in Ouagadougou, Burkina Faso.

BACKGROUND: Dengue is prevalent in as many as 128 countries with more than 100 million clinical episodes reported annually and four billion people estimated to be at risk. While dengue fever is systematically diagnosed in large parts of Asia and South America, the disease burden in Africa is less well investigated. This report describes two consecutive dengue outbreaks in Ouagadougou, Burkina Faso in 2016 and 2017. METHODS: Blood samples of febrile patients received at Schiphra laboratory in Ouagadougou, Burkina Faso, were screened for dengue infection using SD Bioline Dengue Duo rapid diagnostic test kits (Standard Diagnostics, Suwon, Republic of Korea). RESULTS: A total of 1,397 and 1,882 cases were reported by a single laboratory in 2016 and 2017, respectively. Most cases were at least 15 years of age and the results corroborated reports from WHO indicating the circulation of three dengue virus serotypes in Burkina Faso. CONCLUSION: This study complements data from other, simultaneously conducted surveillance efforts, and indicates that the dengue disease burden might be underestimated in sub-Saharan African nations. Dengue surveillance should be enhanced in African settings to determine the burden more accurately, and accelerated efforts towards a dengue vaccine should be put in place

Effect of Dapagliflozin on Cardiovascular Outcomes According to Baseline Kidney Function and Albuminuria Status in Patients With Type 2 Diabetes A Prespecified Secondary Analysis of a Randomized Clinical Trial

ImportanceSodium-glucose cotransporter 2 inhibitors, such as dapagliflozin, promote renal glucose excretion and reduce cardiovascular (CV) deaths and hospitalizations for heart failure (HHF) among patients with type 2 diabetes. The relative CV efficacy and safety of dapagliflozin according to baseline kidney function and albuminuria status are unknown.ObjectiveTo assess the CV efficacy and safety of dapagliflozin according to baseline estimated glomerular filtration rate (eGFR) and urinary albumin to creatinine ratio (UACR).Design, setting, and participantsThis secondary analysis of the randomized clinical trial Dapagliflozin Effect on Cardiovascular Events-Thrombolysis in Myocardial Infarction 58 compared dapagliflozin vs placebo in 17 160 patients with type 2 diabetes and a baseline creatinine clearance of 60 mL/min or higher. Patients were categorized according to prespecified subgroups of baseline eGFR (InterventionsDapagliflozin vs placebo.Main outcomes and measuresThe dual primary end points were major adverse cardiovascular events (myocardial infarction, stroke, and CV death) and the composite of CV death or HHF.ResultsAt baseline, 1265 patients (7.4%) had an eGFR below 60 mL/min/1.73 m2, and 5199 patients (30.9%) had albuminuria. Among patients having data for both eGFR and UACR, 10 958 patients (65.1%) had an eGFR equal to or higher than 60 mL/min/1.73 m2 and an UACR below 30 mg/g (mean [SD] age, 63.7 [6.7] years; 40.1% women), 5336 patients (31.7%) had either an eGFR below 60 mL/min/1.73 m2 or albuminuria (mean [SD] age, 64.1 [7.1] years; 32.6% women), and 548 patients (3.3%) had both (mean [SD] age, 66.8 [6.9] years; 30.5% women). In the placebo group, patients with more CKD markers had higher event rates at 4 years as assessed using the Kaplan-Meier approach for the composite of CV death or HHF (3.9% for 0 markers, 8.3% for 1 marker, and 17.4% for 2 markers) and major adverse cardiovascular events (7.5% for 0 markers, 11.6% for 1 marker, and 18.9% for 2 markers). Estimates for relative risk reductions for the composite of CV death or HHF and for major adverse cardiovascular events were generally consistent across subgroups (both P > .24 for interaction), although greater absolute risk reductions were observed with more markers of CKD. The absolute risk difference for the composite of CV death or HHF was greater for patients with more markers of CKD (0 markers, -0.5%; 1 marker, -1.0%; and 2 markers, -8.3%; P = .02 for interaction). The numbers of amputations, cases of diabetic ketoacidosis, fractures, and major hypoglycemic events were balanced or numerically lower with dapagliflozin compared with placebo for patients with an eGFR below 60 mL/min/1.73 m2 and an UACR of 30 mg/g or higher.Conclusions and relevanceThe effect of dapagliflozin on the relative risk for CV events was consistent across eGFR and UACR groups, with the greatest absolute benefit for the composite of CV death or HHF observed among patients with both reduced eGFR and albuminuria.Trial registrationClinicalTrials.gov Identifier: NCT01730534

Dalla progettazione all’utilizzo di un sistema informativo geologico al servizio del rilevamento geologico: la banca dati della Regione Lombardia e la cartografia geologica derivata

In questa Tesi è descritto il processo di creazione di un Sistema Informativo Geologico e degli strumenti informatici per la gestione dell’informazione su base geografica, o più semplicemente GIS (Geographic Information System), al servizio delle attività di rilevamento geologico, finalizzato alla raccolta dei dati ed alla loro rappresentazione cartografica nell'ambito di un Sistema Informativo Territoriale (SIT). Un SIT è definibile come l'insieme di uomini, strumenti e procedure che, nell’ambito di una organizzazione, permettono l’acquisizione e la distribuzione dei dati relativi alla conoscenza dei fenomeni e degli attori presenti su territorio; tutto questo è facilitato in gran parte dalle capacità e funzionalità dei GIS. Il Sistema Informativo Territoriale orientato alla Geologia (SIG – Sistema Informativo Geologico) della Regione Lombardia è costituito da un gruppo di lavoro composto da geologi, informatici e geologi-informatici dell’Ente regionale e della società Lombardia Servizi (Gruppo Lombardia Informatica). Ho fatto parte del team di consulenza tecnico-scientifica incaricato da Lombardia Servizi per la realizzazione del SIG regionale. I compiti del gruppo di lavoro sono: - definizione di ruoli e metodi per la costituzione del SIG; - definizione delle logiche per la creazione di strumenti finalizzati all’archiviazione del dato geologico in una banca dati geologica e loro manutenzione; Il progetto è inserito nel più ampio processo di aggiornamento della Cartografia Geologica nazionale (progetto CARG). Il SIG ha come principali obiettivi: - la pianificazione ed esecuzione del rilevamento geologico di dettaglio (scala 1:10.000) del territorio lombardo; - la costruzione di un database della geologia di superficie (ma anche del sottosuolo per le aree di pianura) interrogabile e aggiornabile ; - il supporto ai processi di analisi finalizzati alla descrizione della geologia superficiale e ricostruzione degli eventi che hanno creato il paesaggio attuale; - la rappresentazione cartografica dell’ambiente geologico a partire dal database creato. - la distribuzione dell’informazione geologica archiviata in vari formati (cartaceo e digitale); Sono qui descritte ed analizzate criticamente la filosofia di costruzione delle procedure e le soluzioni tecniche e metodologiche adottate per realizzare gli obiettivi prefissi. L’APAT (Agenzia per la Protezione dell'Ambiente e per i servizi Tecnici nazionali) ha ereditato dal Servizio Geologico il compito di rilevare, aggiornare e pubblicare la Carta Geologica d'Italia (progetto nazionale CARG) quale organo cartografico dello Stato in base alla legge 68/60. Nel 1976 era stato completato il rilevamento della Carta geologica d'Italia alla scala 1:100.000 costituita da 278 fogli a copertura del territorio nazionale; per il suo aggiornamento sono stati definiti strumenti normativi idonei a garantire l'omogeneità dei contenuti e della rappresentazione cartografica; la definizione delle norme discende dall'applicazione di linee guida, frutto dell'attività di Commissioni e Gruppi di lavoro, pubblicate nei Quaderni della serie III (ed. APAT). L’Ente Regione Lombardia, per rispondere all’impegno istituzionale di aggiornamento della Carta Geologica, all’interno del più ampio e strutturato Sistema Informativo Territoriale regionale, ha dunque creato il Sistema Informativo Geologico (SIG) regionale. Il rapido evolversi delle ricerche nel campo delle Scienze della Terra e l'importanza che riveste la cartografia geologica nella gestione del territorio, hanno spinto la Regione Lombardia a progettare un rilevamento geologico di dettaglio per dotarsi di una banca dati geologica dalla quale derivare la propria cartografia geologica (alla scala 1:10.000). Sono stati quindi definiti standard specifici rispondenti a questa esigenza di maggior dettaglio (rispetto a quanto indicato dal progetto nazionale CARG) ed è stato pianificato e in gran parte realizzato un rilevamento ex-novo finalizzato alla pubblicazione del dato alla scala del rilevamento e per la sua generalizzazione alle scale 1:25.000 e 50.000. Alla fine del processo saranno stati realizzati 14 fogli del territorio lombardo relativamente alle aree alpine e di passaggio alla pianura (Bergamo, Bormio, Breno, Clusone, Lecco, Iseo, Malonno, Ponte di Legno, Sondrio, Vimercate, Milano, Bagolino, Seregno, Voghera). In tale progetto sono anche coinvolti le Università di Milano, di Pavia e di Bolona, il Politecnico di Milano e il CNR - Centro di Studio per la Geodinamica Alpina e Quaternaria di Milano. L’attività di rilevamento geologico è di competenza dei funzionari regionali della Struttura Sistema Informativo Territoriale della Direzione Generale Territorio e Urbanistica che, coadiuvati da geologi rilevatori, realizzano tutte le fasi del lavoro, dalla raccolta del dato fino alla sua pubblicazione. L’ambiente informatico GIS sviluppato, denominato CARGeo (Cartografia Geologica), permette di inserire i dati raccolti da geologi rilevatori in un database appositamente predisposto, mediante interfacce grafiche semplificate e procedure standard di archiviazione e controllo di correttezza formale. La banca dati è costruita in modo da facilitare l’archiviazione della maggior parte dei dati che normalmente il geologo registra nella carta e nei taccuini di terreno e, allo stesso tempo, guidarlo nella raccolta organica dell’informazione geologica. Nella strutturazione del database è stata privilegiata la possibilità di inserire attributi direttamente associabili agli elementi geometrici anziché attraverso schede associate a punti di osservazione. Il geologo rilevatore interviene per correggere errori di digitalizzazione o di attribuzione con un processo ciclico, fino ad ottenere una banca dati corretta secondo gli standard predefiniti. Gli strumenti di creazione della banca dati permettono anche di: - disegnare gli schemi accessori (sezioni geologiche, schemi stratigrafici e strutturali etc.); - eseguire lo “sfoltimento” e posizionamento delle annotazioni sulla mappa (sigle di unità litologiche e parametri di inclinazione delle giaciture) secondo criteri di leggibilità della carta - creare le legende; - creare banche dati a scala inferiore (1:25.000 e 50.000); - stampare e pubblicare carte geologiche complete di schemi e legende. Il sistema contiene gli strumenti necessari alla migrazione della banca dati dalla struttura proprietaria CARG-Regione Lombardia a quella CARG-APAT secondo la struttura definita nei Quaderni della serie III Il Sistema nel corso del biennio 2006-2007 ha raggiunto la fase di consegna dei dati (derivazione e generalizzazione della banca dati CARG-APAT 1.50.000 da quella 1:10.000 CARG-Regione Lombardia) dei primi fogli completati (ISEO, MALONNO, LECCO e SONDRIO) con ritardo rispetto alla programmazione. Sono state analizzate le cause che hanno portato a questo rallentamento del flusso di lavoro, quindi apportate le necessarie modifiche al Sistema. Sono qui descritti i problemi e le soluzioni trovate per migliorare l'efficienza del sistema. Attualmente il Sistema Informativo Geologico è in una fase di ristrutturazione, che vede la migrazione verso un’architettura informatica basata sulla piattaforma ARCGis® 9.x. Attraverso il Sistema Informativo Geologico viene tentata una sintesi fra le logiche metodologiche dei due ambiti tecnico-scientifici coinvolti (Geologia e Informatica), in un ambiente dove ricercatori e tecnici lavorano sperimentando l’interazione tra le conoscenze e le metodologie conoscitive tipiche delle Scienze Geologiche e le tecnologie e processi logici delle Scienze Informatiche. Con questa Tesi è documentato tutto il percorso di costruzione della banca dati geologica attraverso e all’interno del sistema realizzato assieme gruppo di lavoro composto da geologi e tecnici informatici, cui ho partecipato, riassumendo gli oltre 9 anni di lavoro dall’ideazione del progetto CARGeo, anche in funzione del suo miglioramento

Serum potassium levels, cardiac arrhythmias, and mortality following non-ST-elevation myocardial infarction or unstable angina: insights from MERLIN-TIMI 36

Background: In acute coronary syndrome (ACS), potassium levels 4.0 mEq/L in ACS. Our study evaluated the association between potassium levels, cardiac arrhythmias, and cardiovascular death in patients with non-ST-segment elevation myocardial infarction or unstable angina. Methods: Potassium levels were measured in 6515 patients prior to randomization to receive either ranolazine or a placebo in the MERLIN-TIMI 36 trial. A seven-day continuous electrocardiographic assessment was obtained to determine the incidence of non-sustained ventricular tachycardia (NSVT) and ventricular pauses. The association between potassium levels and cardiovascular death was evaluated using a Cox proportional hazards regression model with multivariable adjustment. Results: NSVT lasting for at least eight consecutive beats occurred more frequently at potassium levels 3 s, which occurred more frequently at potassium levels ⩾5 mEq/L than at potassium levels <3.5 mEq/L (5.9 vs. 2.0%, p=0.03 for trend). There was a U-shaped relationship between the potassium level at admission and both early and late risk of cardiovascular death. Compared with patients with potassium levels of 3.5 to <4 mEq/L, a potassium level <3.5 mEq/L was associated with an increased risk of cardiovascular death at day 14 (2.4 vs. 0.8%, HRadj 3.1, p=0.02) and at one year (6.4 vs. 3.0%, HRadj 2.2, p=0.01). The risk of cardiovascular death at one year was also significantly increased at potassium levels ⩾4.5 mEq/L and a similar trend was noted at potassium levels ⩾5 mEq/L. Conclusions: The lowest risk of cardiovascular death was observed in patients with admission potassium levels between 3.5 and 4.5 mEq/L. Both lower and higher levels of potassium were associated with tachyarrhythmias and bradyarrhythmias, suggesting a potential mechanistic explanation for the increased risk of cardiovascular death at the extremes of potassium homeostasis.Depto. de MedicinaFac. de MedicinaUniversidad Complutense de MadridTRUEpu

Short Sleep Duration, Obstructive Sleep Apnea, Shiftwork, and the Risk of Adverse Cardiovascular Events in Patients After an Acute Coronary Syndrome

Background: It is unknown whether short sleep duration, obstructive sleep apnea, and overnight shift work are associated with the risk of recurrent cardiovascular events in patients after an acute coronary syndrome. Methods and Results: SOLID‐TIMI 52 (The Stabilization of PLaques UsIng Darapladib‐Thrombolysis in Myocardial Infarction 52 Trial) was a multinational, double‐blind, placebo‐controlled trial that enrolled 13 026 patients ≤30 days of acute coronary syndrome. At baseline, all patients were to complete the Berlin questionnaire to assess risk of obstructive sleep apnea and a sleep and shift work survey. Median follow‐up was 2.5 years. The primary outcome was major coronary events (MCE; coronary heart disease death, myocardial infarction, or urgent revascularization). Cox models were adjusted for clinical predictors. Patients who reported <6 hours sleep per night had a 29% higher risk of MCE (adjusted hazard ratio, 1.29; 95% confidence interval, 1.12–1.49; P<0.001) compared with those with longer sleep. Patients who screened positive for obstructive sleep apnea had a 12% higher risk of MCE (1.12; 1.00–1.24; P=0.04) than those who did not screen positive. Overnight shift work (≥3 night shifts/week for ≥1 year) was associated with a 15% higher risk of MCE (1.15; 1.03–1.29; P=0.01). A step‐wise increase in cardiovascular risk was observed for individuals with more than 1 sleep‐related risk factor. Individuals with all 3 sleep‐related risk factors had a 2‐fold higher risk of MCE (2.01; 1.49–2.71; P<0.0001). Conclusions: Short sleep duration, obstructive sleep apnea, and overnight shift work are under‐recognized as predictors of adverse outcomes after acute coronary syndrome. Increased efforts should be made to identify, treat, and educate patients about the importance of sleep for the potential prevention of cardiovascular events. Clinical Trial Registration URL: http://www.clinicaltrials.gov. Unique identifier: NCT01000727