Comparison between Highly Complex Location Models and GAMLSS.

This paper presents a discussion regarding regression models, especially those belonging to the location class. Our main motivation is that, with simple distributions having simple interpretations, in some cases, one gets better results than the ones obtained with overly complex distributions. For instance, with the reverse Gumbel (RG) distribution, it is possible to explain response variables by making use of the generalized additive models for location, scale, and shape (GAMLSS) framework, which allows the fitting of several parameters (characteristics) of the probabilistic distributions, like mean, mode, variance, and others. Three real data applications are used to compare several location models against the RG under the GAMLSS framework. The intention is to show that the use of a simple distribution (e.g., RG) based on a more sophisticated regression structure may be preferable than using a more complex location model.

Predicting survival function and identifying associated factors in patients with renal insufficiency in the metropolitan area of Maringá, Paraná State, Brazil.

Renal insufficiency is a serious medical and public health problem worldwide. Recently, although many surveys have been developed to identify factors related to the lifetime of patients with renal insufficiency, controversial results from several studies suggest that researches should be conducted by region. Thus, in this study we aim to predict and identify factors associated with the lifetime of patients with chronic renal failure (CRF) in the metropolitan area of Maringá, Paraná State, Brazil, based on the generalized additive models for location, scale and shape (GAMLSS) framework. Data used in this study were collected from the Maringá Kidney Institute and comprehends 177 patients (classified with CRF and mostly being treated under the Brazilian Unified National Health System) enrolled in a hemodialysis program from 1978 up to 2010. By using this approach, we concluded that in other regions, gender, kidney transplant indicator, antibodies to hepatitis B and antibodies to hepatitis C are significant factors that affect the expected lifetime.

Predicting survival function and identifying associated factors in patients with renal insufficiency in the metropolitan area of Maringá, Paraná State, Brazil / A predição da função de sobrevivência e identificação de fatores associados em pacientes renais crônicos na área metropolitana de Maringá, Paraná, Brasil / Prediciendo la esperanza de vida e identificando factores asociados en pacientes con insuficiencia renal en el área metropolitana de Maringá, Estado de Paraná, Brasil

Renal insufficiency is a serious medical and public health problem worldwide. Recently, although many surveys have been developed to identify factors related to the lifetime of patients with renal insufficiency, controversial results from several studies suggest that researches should be conducted by region. Thus, in this study we aim to predict and identify factors associated with the lifetime of patients with chronic renal failure (CRF) in the metropolitan area of Maringá, Paraná State, Brazil, based on the generalized additive models for location, scale and shape (GAMLSS) framework. Data used in this study were collected from the Maringá Kidney Institute and comprehends 177 patients (classified with CRF and mostly being treated under the Brazilian Unified National Health System) enrolled in a hemodialysis program from 1978 up to 2010. By using this approach, we concluded that in other regions, gender, kidney transplant indicator, antibodies to hepatitis B and antibodies to hepatitis C are significant factors that affect the expected lifetime.

A insuficiência renal crônica é um grave problema clínico e de saúde pública no mundo inteiro. Recentemente, apesar de muitas pesquisas já realizadas para identificar os fatores relacionados à evolução dos pacientes renais crônicos, os resultados conflitantes entre diversos estudos sugerem a necessidade de pesquisas por região. Portanto, o estudo busca predizer e identificar os fatores associados à evolução dos pacientes com insuficiência renal crônica (IRC) na área metropolitana de Maringá, Estado do Paraná, Brasil, com base nos modelos aditivos generalizados para localização, escala e forma (GAMLSS). Os dados utilizados neste estudo foram coletados no Instituto do Rim de Maringá e incluem 177 pacientes (classificados com IRC, a maioria tratada no Sistema Único de Saúde) inclusos no programa de hemodiálise entre 1978 e 2010. Através dessa abordagem, concluímos que em outras regiões, gênero, indicação para transplante renal e anticorpos aos vírus das hepatites B e C são fatores significativos que afetam a sobrevivência esperada.

La insuficiencia renal representa un problema médico y de salud pública serio en todo el mundo. Recientemente, pese a los muchos estudios que se han desarrollado para identificar factores relacionados con la esperanza de vida de los pacientes con insuficiencia renal, los resultados controvertidos de algunos estudios sugieren que las investigaciones deberían realizarse por regiones. No obstante, en este trabajo pretendemos predecir e identificar los factores asociados con la esperanza de vida de pacientes con fallo renal crónico (FRC) en el área metropolitana de Maringá, Estado de Paraná, Brasil, basado en el marco de modelos aditivos generalizados para ubicación, escala y forma (GAMLSS por sus siglas en inglés). Los datos usados en este estudio fueron recogidos del Instituto del riñón de Maringá y comprende a 177 pacientes (clasificados con FRC y en su mayoría siendo tratados en el Sistema Único de Salud), inscritos en un programa de hemodiálisis desde 1978 hasta 2010. Usando este enfoque, concluimos que en otras regiones, género, indicador de trasplante de riñón, anticuerpos a la hepatitis B y anticuerpos a la hepatitis C son factores significativos que afectan a la esperanza de vida.