Search results for "Markov chains"
showing 10 items of 73 documents
Optimization of anemia treatment in hemodialysis patients via reinforcement learning
2013
Objective: Anemia is a frequent comorbidity in hemodialysis patients that can be successfully treated by administering erythropoiesis-stimulating agents (ESAs). ESAs dosing is currently based on clinical protocols that often do not account for the high inter- and intra-individual variability in the patient's response. As a result, the hemoglobin level of some patients oscillates around the target range, which is associated with multiple risks and side-effects. This work proposes a methodology based on reinforcement learning (RL) to optimize ESA therapy. Methods: RL is a data-driven approach for solving sequential decision-making problems that are formulated as Markov decision processes (MDP…
Comprehensive geriatric assessment decreases prevalence of orthostatic hypotension in older persons
2013
Background: Orthostatic hypotension (OH) is associated with significant morbidity and mortality among older people. We have studied whether its prevalence can be reduced by a Comprehensive Geriatric Assessment (CGA). Study design and setting: 1000 randomly-selected persons aged ≥75 years were divided into intervention ( n = 500) and control groups ( n = 500). We focused on those subjects in whom an orthostatic blood pressure test had been performed at least once during the study period (2004–2007) ( n = 365 and 332 for intervention and control groups, respectively). A CGA, including evaluation of the adequacy of the medication, was performed annually in the intervention group but not in th…
The unobserved pattern of material hardship and health among older Americans
2019
This paper investigates the relationship between self-reported health and material hardship among older Americans. Differently from income-based measures, material hardship provides a more specific description of the concrete adversities faced by the elderly. We have used the last six waves of the Health and Retirement Study to explore the relative contributions of state dependence, unobserved heterogeneity and time-specific shocks on reporting poor health, experiencing food insecurity and medication cutbacks. We have used a Latent Markov model to estimate a multivariate non-linear system of equations for panel data allowing time-varying unobserved heterogeneity. Our results reveal a high s…
Personalized cost-effectiveness of boceprevir-based triple therapy for untreated patients with genotype 1 chronic hepatitis C
2014
Abstract Background We assessed the cost-effectiveness of boceprevir-based triple therapy compared to peginterferon alpha and ribavirin dual therapy in untreated patients with genotype 1 chronic hepatitis C; patients were discriminated according to the combination of baseline plus on-treatment predictors of boceprevir-based triple therapy. Methods Cost-effectiveness analysis performed according to data from the available published literature. The target population was composed of untreated Caucasian patients, aged 50 years, with genotype 1 chronic hepatitis C, and these were evaluated over a lifetime horizon by Markov model. The study was carried out from the perspective of the Italian Nati…
Cost-effectiveness of sorafenib treatment in field practice for patients with hepatocellular carcinoma
2013
The purpose was to assess the cost-effectiveness of sorafenib in the treatment of hepatocellular carcinoma (HCC) patients incorporating current prices and the results of the recent published field practice SOraFenib Italian Assessment (SOFIA) study. We created a Markov Decision Model to evaluate, in a hypothetical cohort of Caucasian male patients, aged 67 years with Barcelona Clinic Liver Cancer (BCLC) C HCC, or BCLC B HCC who were unfit or failed to respond to locoregional therapies, well compensated cirrhosis, and with performance status 0-1 according to Eastern Cooperative Oncology Group (ECOG), the cost-effectiveness of the following strategies: (1) full or dose-adjusted sorafenib for …
Cost-effectiveness analysis of pemetrexed versus docetaxel in the second-line treatment of non-small cell lung cancer in Spain: results for the non-s…
2010
Abstract Background The objective of this study was to conduct a cost-effectiveness evaluation of pemetrexed compared to docetaxel in the treatment of advanced or metastatic non-small cell lung cancer (NSCLC) for patients with predominantly non-squamous histology in the Spanish healthcare setting. Methods A Markov model was designed consisting of stable, responsive, progressive disease and death states. Patients could also experience adverse events as long as they received chemotherapy. Clinical inputs were based on an analysis of a phase III clinical trial that identified a statistically significant improvement in overall survival for non-squamous patients treated with pemetrexed compared …
Cost effectiveness of boceprevir or telaprevir for previously treated patients with genotype 1 chronic hepatitis C.
2013
Background & Aims Randomised controlled trials (RCTs) show that triple therapy (TT) with peginterferon alfa, ribavirin, and boceprevir (BOC) or telaprevir (TVR) is more effective than peginterferon-ribavirin dual therapy (DT) in the treatment of genotype 1 (G1) chronic hepatitis C (CHC) patients with previous relapse (RR), partial response (PAR), and null-response (NR). We assess the cost-effectiveness of TT compared to no therapy in the treatment of patients previously treated with G1 CHC. Methods The available published literature provided the data source. The target population was made up of previously treated Caucasian patients with G1 CHC and these were evaluated over a lifetime horizo…
Increased Activity of Coagulation Factor XII (Hageman Factor) Causes Hereditary Angioedema Type III
2006
International audience; Hereditary angioedema (HAE) is characterized clinically by recurrent acute skin swelling, abdominal pain, and potentially life-threatening laryngeal edema. Three forms of HAE have been described. The classic forms, HAE types I and II, occur as a consequence of mutations in the C1-inhibitor gene. In contrast to HAE types I and II, HAE type III has been observed exclusively in women, where it appears to be correlated with conditions of high estrogen levels--for example, pregnancy or the use of oral contraceptives. A recent report proposed two missense mutations (c.1032C-->A and c.1032C-->G) in F12, the gene encoding human coagulation factor XII (FXII, or Hageman factor…
Uncontrolled diabetes and health care utilisation:A bivariate latent Markov model approach
2018
Although uncontrolled diabetes (UD) or poor glycaemic control is a widespread condition with potentially life-threatening consequences, there is sparse evidence of its effects on health care utilisation. We jointly model the propensities to consume health care and UD by employing an innovative bivariate latent Markov model that allows for dynamic unobserved heterogeneity, movements between latent states and the endogeneity of UD. We estimate the effects of UD on primary and secondary health care consumption using a panel dataset of rich administrative records from Spain and measure UD using a biomarker. We find that, conditional on time-varying unobservables, UD does not have a statisticall…
Bayesian methods in cost-effectiveness studies: objectivity, computation and other relevant aspects.
2009
In a probabilistic sensitivity analysis (PSA) of a cost-effectiveness (CE) study, the unknown parameters are considered as random variables. A crucial question is what probabilistic distribution is suitable for synthesizing the available information (mainly data from clinical trials) about these parameters. In this context, the important role of Bayesian methodology has been recognized, where the parameters are of a random nature. We explore, in the context of CE analyses, how formal objective Bayesian methods can be implemented. We fully illustrate the methodology using two CE problems that frequently appear in the CE literature. The results are compared with those obtained with other popu…