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    Association of Apolipoprotein E Polymorphism with Intravitreal Ranibizumab Treatment Outcomes in Age-Related Macular Degeneration
    (TAYLOR & FRANCIS INC, 2016) Bakbak, Berker; Ozturk, Banu Turgut; Zamani, Ayse Gul; Gonul, Saban; Iyit, Neslihan; Gedik, Sansal; Yildirim, M. Selman
    Purpose: Genetic factors are known to influence the response to anti-vascular endothelial growth factor (VEGF) treatment in exudative age-related macular degeneration (AMD). The current study was conducted to investigate the association of Apolipoprotein E (ApoE) polymorphism with the treatment response to ranibizumab for exudative AMD.Methods: One hundred nine eyes (109 patients, 59.6% male, mean age 63.847.22 years) treated with intravitreal ranibizumab injections were included in the analysis. Smoking status and lesion type were recorded. Patients were categorized into three groups according to visual acuity (VA) change at 6 months after the first injection: VA loss >5 Early Treatment Diabetic Retinopathy Study (ETDRS) letters (Group 1); VA change between five ETDRS letters gain and loss (Group 2); VA improvement >5 ETDRS letters (Group 3). The association of ApoE gene polymorphisms with the three groups was evaluated.Results: Both smoking status and lesion type showed no significant association with VA change (p=0.12 and p=0.64, respectively). A lower frequency of 2 and a higher frequency of 4 were observed in Group 3 (2.9 and 25.7%, respectively). VA improvement with more than five ETDRS letters was significantly associated with the presence of the 4 genotype (p=0.01).Conclusions: This study demonstrated that carriers of the ApoE 4 polymorphism genotype show demonstrable improvement in VA after treatment with ranibizumab in exudative AMD. ApoE polymorphism identification may be used as a genetic screening to tailor individualized therapeutic approach for optimal treatment in neovascular AMD.
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    Constitution of random intercept and slope model (RISM) as a special case of linear mixed models (LMMs) for repeated measurements data
    (ELSEVIER SCIENCE INC, 2011) Iyit, Neslihan; Genc, Asir
    In this paper, for the aim of modeling variance-covariance structure matrix of the response variables vector in random intercept and slope model (RISM) from linear mixed models (LMMs) for repeated measurements data, 13 different homogeneous and heterogeneous variance-covariance structure models are investigated comparatively in an application from a clinical trial. (C) 2011 Elsevier Inc. All rights reserved.
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    Modelling world energy security data from multinomial distribution by generalized linear model under different cumulative link functions
    (SCIENDO, 2018) Iyit, Neslihan
    Energy security is one of the major components of energy sustainability in the world's energy performance. In this study, energy security is taken as an ordinal response variable coming from the multinomial distribution with the energy grade levels A, B, C, and D. Thereafter, the world energy security data is tried to be statistically modelled by using generalized linear model (GLM) approach for the ordinal response variable under different cumulative link functions. The cumulative link functions comparatively used in this study are cumulative logit, cumulative probit, cumulative complementary log-log, cumulative Cauchit, and cumulative negative log-log. In order to avoid a multicollinearity problem in the data structure, principal component analysis (PCA) technique is integrated with the GLM approach for the ordinal response variable. In this study, statistically, the importance of determining the best cumulative link function on the accuracy of parameter estimates, confidence intervals, and hypothesis tests in the GLM for the multinomially distributed response variable is highlighted. In terms of energy evaluation, by using cumulative logit as the best cumulative link function, energy sources consumptions, electricity productions from nuclear energy, natural gas, oil, coal, and hydroelectric, energy use per capita and energy imports are found to have statistically significant effects on energy security in the world's energy performance.