title: Quasi-Poisson versus negative binomial regression models in identifying factors affecting initial CD4 cell count change due to antiretroviral therapy administered to HIV-positive adults in North-West Ethiopia (Amhara region).
abstract: CD4 cells are a type of white blood cells that plays a significant role in protecting humans from infectious diseases. Lack of information on associated factors on CD4 cell count reduction is an obstacle for improvement of cells in HIV positive adults. Therefore, the main objective of this study was to investigate baseline factors that could affect initial CD4 cell count change after highly active antiretroviral therapy had been given to adult patients in North West Ethiopia.
  
  
  
  A retrospective cross-sectional study was conducted among 792 HIV positive adult patients who already started antiretroviral therapy for 1 month of therapy. A Chi square test of association was used to assess of predictor covariates on the variable of interest. Data was secondary source and modeled using generalized linear models, especially Quasi-Poisson regression.
  
  
  
  The patients' CD4 cell count changed within a month ranged from 0 to 109 cells/mm3with a mean of 15.9 cells/mm3and standard deviation 18.44 cells/mm3. The first month CD4 cell count change was significantly affected by poor adherence to highly active antiretroviral therapy (aRR = 0.506, P value = 2e-16), fair adherence (aRR = 0.592, P value = 0.0120), initial CD4 cell count (aRR = 1.0212, P value = 1.54e-15), low household income (aRR = 0.63, P value = 0.671e-14), middle income (aRR = 0.74, P value = 0.629e-12), patients without cell phone (aRR = 0.67, P value = 0.615e-16), WHO stage 2 (aRR = 0.91, P value = 0.0078), WHO stage 3 (aRR = 0.91, P value = 0.0058), WHO stage 4 (0876, P value = 0.0214), age (aRR = 0.987, P value = 0.000) and weight (aRR = 1.0216, P value = 3.98e-14).
  
  
  
  Adherence to antiretroviral therapy, initial CD4 cell count, household income, WHO stages, age, weight and owner of cell phone played a major role for the variation of CD4 cell count in our data. Hence, we recommend a close follow-up of patients to adhere the prescribed medication for achievements of CD4 cell count change progression.
authors.affiliation: Department of Statistics, Bahir Dar University, Bahir Dar, Ethiopia.
authors.forename: Awoke
authors.initials: A
authors.lastname: Seyoum
authors.affiliation: Department of Statistics, University of South Africa, Pretoria, South Africa.
authors.forename: Principal
authors.initials: P
authors.lastname: Ndlovu
authors.affiliation: School of Mathematics, Statistics and Computer Science, University of KwaZulu Natal, Durban, South Africa.
authors.forename: Temesgen
authors.initials: T
authors.lastname: Zewotir
mesh_terms: D000328:Adult; D044966:Anti-Retroviral Agents / Q000097:blood / Q000276:immunology / Q000627:therapeutic use*; D023241:Antiretroviral Therapy, Highly Active / Q000379:methods; D018791:CD4 Lymphocyte Count; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D003430:Cross-Sectional Studies; D018450:Disease Progression; D005002:Ethiopia / Q000453:epidemiology; D005260:Female; D015658:HIV Infections / Q000097:blood / Q000188:drug therapy / Q000276:immunology; D006679:HIV Seropositivity / Q000097:blood* / Q000188:drug therapy* / Q000453:epidemiology / Q000276:immunology; D006801:Humans; D008297:Male; D008875:Middle Aged; D016012:Poisson Distribution; D012189:Retrospective Studies; D012959:Socioeconomic Factors
chemical_list: D044966:Anti-Retroviral Agents
keywords: CD4 cell count change; HAART; Longevity; Negative binomial regression; Quasi-Poisson regression