Longitudinal Data Analysis of the Hematological Changes in Individuals Exposed to Chronic low-dose radiation

• Main Authors: Ya-Ting Hsu, 許雅婷
• Other Authors: I-Feng Lin
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/41181140009520663887

碩士 === 國立陽明大學 === 公共衛生研究所 === 93 === The research analyzes the longitudinal effects in hematology of radiation-polluted residents, and discusses the roles of cumulative radiation dose and relocation time (the duration from moving out of the polluted housings to health check up) in hematological indices. In the past, the Hematology data of the Taiwan radiation housing residents was exclusively based on the comparatively lowly dosed primary school students who had been taught in polluted classrooms. Now this research broadens to the different age groups of patients who have done check ups at the National Taiwan University Hospital. The 414 patients have intact cumulated dosage and move records, and have all been exposed to doses over 5mSv. The model for longitudinal data is mainly composed of the Likelihood Method’s Linear mixed model with parametric covariance structure. The different ages and gender adjustment are of the following five: directly place age and gender information in piecewise mode to set multiple dummy variables in the Linear mixed model with parametric covariance structure, and using Cubic smoothing splines and Thin-plate smoothing splines; two kinds of Nonparametric regression models which set two different smoothing parameters. Upon adjusting the ages and genders using the nonparametric regression and residual estimated by the linear mixed model with parametric covariance structure, the research shows that RBC, Hemoglobin, Hematocrit, and Neutrophil were shown to be negatively and significantly associated with the relocation time. On the other hand, WBC, MCV, MCHC, and Platelet were positively associated with the relocation time. However, there is no significant association between the relocation time and Lymphocyte. In other words, the influence of Taiwan’s radiation cumulated dose (TCD) only affects Neutrophil, as significantly association that the average of TCD in exposures above 5mSv is higher than TCD in exposures below 5mSv. Otherwise, there is no significant dose-response effect that exists between the other blood cells. Investigation in gender and the relocation time indicates that Hemoglobin, Hematocrit, MCHC, Neutrophil, and Platelet in women are more prone to move up or down the scale compared men. However, men’s RBC, WBC, and MCV lead the women’s in reaction to time while Lymphocyte appears to have no significant association whether in men or women. The effects on men’s Neutrophil and women’s RBC by TCD are obvious; the average rate of increasing Neutrophil in men is speedier than women’s, and women’s average RBC decreases. Combining with five adjustments of gender and age by nonparametric regression and parametric regression, it is shown that although the P-values vary, the parametric estimates and indications are consistent. These indicators of Hematology’s deliberate progression could be the result of natural healing of body but could also be the early symptoms of injuries or diseases which have long incubation periods. As to if these indicators will continue to evolve or stay as they are, it is a question that will require a much longer period of observation.