Poisson-Lognormal Mixed Model Based Estimation in Clustered Longitudinal Count Data Analysis

Poisson mixed models are useful for accommodating the overdispersion and correlations often observed among count data. These models are generated from the well-known independent Poisson model by adding normally distributed random effects to the linear predictor, and they are known as Poisson-log-normal mixed models. Unfortunately, a full likelihood analysis for such Poisson mixed models is hampered by the need for numerical integration. In this paper, generalised estimating equations procedure is discussed for the estimation of the parameters of the Poisson-log-normal mixed model under a longitudinal set-up.Keywords: count clustered data, higher order structural moments, mixed effects, multivariate repeated measures, normal based higher order longitudinal moments

Estimating the effects of the factors underlying the progression of Familial Adenomatous Polyposis using Longitudinal Com-­‐Poisson Model

This paper aims at developing a statistical model capable of quantifying the effects of various factors on the progression of Familial Adenomatous Polyposis (FAP), a genetic disorder affecting the colon and rectum in human beings. The progression of FAP in affected individuals is monitored by counting the number of polyps developed over a period of time. These count responses repeatedly observed over time are over-­‐dispersed and highly correlated resulting into a complicated longitudinal count data structure, which render the application of commonly, used Gaussian regression model useless. We designed a statistical model based on Com-­‐ Poisson distribution, which can efficiently analyze such a data structure. The estimates of over-­‐dispersion as well as correlation parameters confirm the nature of real data. Analysis of the model indicates that males are 50% more at risk to develop polyps than females. With respect to the type of treatment, the application of vitamin C and E with high fiber treatment is a better remedy followed by vitamin C and E only as compared to placebo. In men as well as in women, initial polyp counts positively affect the polyp counts at a given time.KEY WORDS: Familial adenomatous polyposis; Longitudinal responses; Correlation and overdispersion; Com-­ ‐Poisson mode

[TAME]-esterase — A new cardiovascular risk factor in smokers

610-612A mathematical model has been proposed to study the effect of [TAME] esterase on blood clotting time. Using this model, clotting time was found to decrease by 30% with increasing plasma [TAME] esterase activity in a group of smokers. It is hypothesized that [TAME] esterase through its effect on Hageman factor could affect clotting time. However mechanism of clotting by [TAME] esterase remains to be elucidated. It is concluded that [TAME] esterase is involved in the cascade of reactions leading to blood coagulation and increased [TAME] esterase activity could be an additional risk factor for possible cerebro-vascular accidents in smokers

Quality of Life in End Stage Renal Failure Patients Undergoing Dialysis in Mauritius

We assessed the quality of life of 45 patients with end stage renal failure undergoing dialysis in Mauritius using the standard United Kingdom version of the Short Form 36 Items Health Survey (SF36) questionnaire. Our findings showed that gender, level of social and emotional support, marital status, and travel time were variably significant predictors of higher scores in specific dimensions. No significant relationship was found between SF36 subscales and age, occupation, length of time on haemodialysis, and household numbers. Response rate was high at 90%. Overall, health related quality of life of ESRD patients is poor. Further studies are required to ascertain whether altering those predictor variables that are amenable to intervention by health care professionals could be associated with improvements in health related quality of life.Keywords: health, quality of life, end stage renal disease, Mauritiu