Parmsurv: a SAS Macro for Flexible Parametric Survival Analysis with Long-Term Predictions

Health economic evaluations often require predictions of survival rates beyond the follow-up period. Parametric survival models can be more convenient for economic modelling than the Cox model. The generalized gamma (GG) and generalized F (GF) distributions are extensive families that contain almost all commonly used distributions with various hazard shapes and arbitrary complexity. In this study, we present a new SAS macro for implementing a wide variety of flexible parametric models including the GG and GF distributions and their special cases, as well as the Gompertz distribution. Proper custom distributions are also supported. Different from existing SAS procedures, this macro not only supports regression on the location parameter but also on ancillary parameters, which greatly increases model flexibility. In addition, the SAS macro supports weighted regression, stratified regression and robust inference. This study demonstrates with several examples how the SAS macro can be used for flexible survival modeling and extrapolation.Comment: 15 pages, 1 figure, 10 tables, accepted by The Clinical Data Science Conference - PHUSE US Connect 202

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Méthodes de traitement de données en chronobiologie

Doctorat en Sciencesinfo:eu-repo/semantics/nonPublishe

Régression de Fourier avec contrainte

Nous proposons une méthode de régression de Fourier avec contrainte. La procédure est destinée à l'interprétation des expériences donnant un nombre restreint d'observations inégalement réparties sur une période. Utilisée avec prudence, cette méthode permet d'évaluer les caractéristiques importantes de rythmes biologiques.De Prins J., Malbecq William. Régression de Fourier avec contrainte. In: Bulletin de la Classe des sciences, tome 66, 1980. pp. 130-142

Analyse spectrale pour données non équidistantes

L'article décrit une méthode d'analyse spectrale non paramétrique adaptée aux observations irrégulièrement espacées dans le temps et basée sur une estimation par classes de la fonction de corrélation. La transformée de Fourier de cette fonction donne la densité spectrale énergétique. Une application au rythme circadien de la température orale est présentée.De Prins J., Malbecq William. Analyse spectrale pour données non équidistantes. In: Bulletin de la Classe des sciences, tome 69, 1983. pp. 287-294

Statistical procedures in chronobiology and chronopharmacology

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Coronary heart disease risk factors and LDL cholesterol-lowering efficacy of fibrates and simvastatin

The objective of this study was to assess the low-density lipoprotein cholesterol (LDL-C) lowering efficacy of fibric acid derivatives (fibrates) and simvastatin as a function of coronary heart disease (CHD) risk status, stratified according to National Cholesterol Education Program guidelines. Two independent databases were analysed retrospectively. The first data set originated from a consecutive sample of 6340 patients with primary hypercholesterolaemia who completed the diet plus fibrate treatment phase of the Belgian General Practitioners Trial, an open-label, prospective study conducted in a primary care setting. The second data set was derived from 782 participants in five randomised, double-blind studies that each compared a specific fibrate with simvastatin. The main outcome measures were percentage of subjects reaching LDL-C treatment goal, and mean percentage reduction in LDL-C across 5 (first data set) or 3 (second data set) CHD risk strata. In the Belgian General Practitioners Trial, LDL-C lowering efficacy of fibrates was inversely related to CHD risk status as 15.0% of patients with prior CHD reached the LDL-C goal < 4.13 mmol/L (< 160 mg/dl) vs 30.2% of those without CHD and no other risk factor (p < 0.0001 after adjustment for baseline LDL-C acid triglycerides). Adjusted mean percentage reductions in LDL-C were 15.1 and 18.2, in these strata, respectively (p < 0.05). Younger age, male gender, high blood pressure, low high-density lipoprotein cholesterol, and history of prior CHD were significant (p < 0.05) negative determinants of both outcome measures in multivariate analyses that adjusted for other risk factors. In the pooled analysis of five randomised trials, the percentage of fibrate-treated patients with prior atherosclerotic disease reaching LDL-C goal < 4.20 mmol/L (< 162 mg/dl) was significantly lower when compared with those without CHD and no risk factor other than LDL-C (adjusted odds ratio = 0.46; p = 0.009), while simvastatin efficacy was similar across CHD risk strata. In conclusion, our results, derived from two independent databases, suggest that the LDL-C lowering efficacy of fibrates, but not of simvastatin, is inversely related to CHD risk status. This exploratory analysis must be confirmed by future prospective studies.SCOPUS: ar.jinfo:eu-repo/semantics/publishe