Biomedical subjects

Shu-Hui Chang

Publications and source records attributed to Shu-Hui Chang.

10 recordsLinked to original sources

PubMed2007

Survival, mortality, and complications in patients with beta-thalassemia major in northern Taiwan.

BACKGROUND: Advances in treatment have improved the prognosis in beta-thalassemia major. We present the survival and complications pattern of those patients in northern Taiwan born after 1970. PROCEDURE: One-hundred and sixty patients with beta-thalassemia major born after 1970 were collected. The Kaplan-Meier method and log-rank test were used to estimate and compare survival. Cox regression models were used to examine the associations of bone marrow transplantation (BMT), time of BMT procedure, and time of complications with survival. RESULTS: Better survival was observed for patients born after 1980 (P = 0.0121). Heart disease, BMT-related deaths, and infections were the main causes of death. Among the living patients over age 15, hypogonadotropic hypogonadism, HCV infection, diabetes, heart failure, and arrhythmia were the common complications. No patients under age 15 had complications. CONCLUSIONS: Survival for patients with beta-thalassemia major has improved significantly in Taiwan. More time is required to demonstrate whether these modalities added to the treatment of these patients will impact favorably on their outcome. Our success with BMT is improving and we are now in a position to offer this curative alternative.

Adolescent↗

PubMed2006

Nonparametric estimation of sojourn time distributions for truncated serial event data--a weight-adjusted approach.

In follow-up studies, survival data often include subjects who have had a certain event at recruitment and may potentially experience a series of subsequent events during the follow-up period. This kind of survival data collected under a cross-sectional sampling criterion is called truncated serial event data. The outcome variables of interest in this paper are serial sojourn times between successive events. To analyze the sojourn times in truncated serial event data, we need to confront two potential sampling biases arising simultaneously from a sampling criterion and induced informative censoring. In this study, nonparametric estimation of the joint probability function of serial sojourn times is developed by using inverse probabilities of the truncation and censoring times as weight functions to accommodate these two sampling biases under various situations of truncation and censoring. Relevant statistical properties of the proposed estimators are also discussed. Simulation studies and two real data are presented to illustrate the proposed methods.

Accidents↗

PubMed2006

Community-based tai chi and its effect on injurious falls, balance, gait, and fear of falling in older people.

BACKGROUND AND PURPOSE: It is important to determine the effect of adherence to a tai chi program on falls and related functional outcomes in older people. This study examined the effect of a community-based tai chi program on injurious falls, balance, gait, and fear of falling among people aged 65 years and older in Taiwan. SUBJECTS AND METHODS: In 6 rural villages in Taichung County, 1,200 subjects participated in the initial assessment. During a 1-year intervention period, all study villages were provided with education on fall prevention. Two villages had been provided tai chi exercise (n=472 participants or "tai chi villagers"), and 4 villages served as control villages (n=728 participants or "control villagers"). Injurious falls were ascertained by telephone interviews every 3 months over a 2-year study period; additionally, balance, gait, and fear of falling were assessed in 2 follow-up assessments. RESULTS: Eighty-eight subjects, 83 from the tai chi villages and 5 from the control villages, participated and practiced in the tai chi program (the group labeled "tai chi practitioners"). After the tai chi program, injurious falls among the control villagers significantly declined by 44% (adjusted rate ratio [RR]=0.56; 95% confidence interval [CI]=0.36-0.92). Compared with the results for the control villagers, the decline was 31% greater (RR=0.69; 95% CI=0.30-1.56) among the tai chi villagers and 50% greater (RR=0.5; 95% CI=0.11-2.17) among the tai chi practitioners; the results did not reach statistical significance. Furthermore, compared with the scores for the control villagers, the scores for the tai chi practitioners increased by 1.8 points (95% CI=0.2-3.4) on the Tinetti Balance Scale and increased by 0.9 point (95% CI=0.1-1.8) on the Tinetti Gait Scale. No significant changes in the fear of falling were detected among the tai chi practitioners, tai chi villagers, and control villagers. DISCUSSION AND CONCLUSION: Tai chi can prevent a decline in functional balance and gait among older people. However, the reduction in injurious falls attained with tai chi did not reach statistical significance; the statistical inefficiency may have resulted partly from the large decline in injurious falls in control villagers. Finally, the unexpected effect of educational intervention on reducing injurious falls in different settings needs to be further examined.

Accidental Falls↗

PubMed2005

Incidence of tuberculosis in mountain areas and surrounding townships: dose-response relationship by geographic analysis.

PURPOSE: The incidence of tuberculosis (TB) in Taiwan is known to be high in aboriginal mountain areas and low in the surrounding non-mountain areas. The aim of this study was to assess whether TB incident cases in the surroundings of mountain areas decreased with distance from foci of mountain areas. METHODS: The mountain areas in Taiwan are adjacent to each other and divided into four geographic groups. Townships with high TB incidence in each group were treated as the foci of TB infection. The surrounding townships were then classified, by distance away from foci, into three levels: < 20 km, 20 to 40 km, and 40 to 60 km. Data were obtained on a total of 84,366 TB cases from 1991 to 1997 from the Taiwan Tuberculous Disease Registry Center. RESULTS: The incidence of TB in each of the four groups was significantly higher in the mountain areas compared with non-mountain areas, with relative risks ranging from 8.4 (95% confidence interval [CI], 7.8-9.1) for the southern group to 15.0 (95% CI, 13.4-16.9) for the northern group. Relative risks for surrounding townships decreased with distance in all four groups. Such a gradient relationship was statistically significant. CONCLUSIONS: A significant dose-response relationship between distance from townships with a high incidence of TB and the incidence of TB in the surrounding areas has been demonstrated.

Adolescent↗

PubMed2005

Computer-aided disease prediction system: development of application software with SAS component language.

AIMS: The intricacy of predictive models associated with prognosis and risk classification of disease often discourages medical personnel who are interested in this field. The aim of this study was therefore to develop a computer-aided disease prediction model underpinning a step-by-step statistics-guided approach including five components: (1) data management; (2) exploratory analysis; (3) type of predictive model; (4) model verification; (5) interactive mode of disease prediction using SAS 8.02 Windows 2000 as a platform. METHODS: The application of this system was illustrated by using data from the Swedish Two-County Trial on breast cancer screening. The effects of tumour size, node status, and histological grade on breast cancer death using logistic regression model or survival models were predicted. A total of 20 questions were designed to exemplify the usefulness of each component. We also evaluated the system using a controlled randomized trial. Times to finish the above 20 questions were used as endpoint to evaluate the performance of the current system. User satisfaction with the current system such as easy to use, the efficiency of risk prediction, and the reduction of barrier to predictive model was also evaluated. RESULTS: The intervention group not only performed more efficiently than the control group but also satisfied with this application software. CONCLUSIONS: The MD-DP-SOS system characterized by menu-driven style, comprehensiveness, accuracy and adequacy assessment, and interactive mode of disease prediction is helpful for medical personnel who are involved in disease prediction.

Decision Support Techniques↗

PubMed2004

Estimating marginal effects in accelerated failure time models for serial sojourn times among repeated events.

Recurrent event data are commonly encountered in longitudinal studies when events occur repeatedly over time for each study subject. An accelerated failure time (AFT) model on the sojourn time between recurrent events is considered in this article. This model assumes that the covariate effect and the subject-specific frailty are additive on the logarithm of sojourn time, and the covariate effect maintains the same over distinct episodes, while the distributions of the frailty and the random error in the model are unspecified. With the ordinal nature of recurrent events, two scale transformations of the sojourn times are derived to construct semiparametric methods of log-rank type for estimating the marginal covariate effects in the model. The proposed estimation approaches/inference procedures also can be extended to the bivariate events, which alternate themselves over time. Examples and comparisons are presented to illustrate the performance of the proposed methods.

Age of Onset↗

PubMed2003

A longitudinal study of risk factors for motorcycle crashes among junior college students in Taiwan.

A cohort of 4729 junior college students in an urban and a rural area in Taiwan was followed up for a period of 20 months. Students' characteristics, including riding exposures, as well as human, vehicular, and environmental factors were collected using one initial and three follow-up questionnaires. The Anderson-Gill (AG) multiplicative intensity model was used to determine the risk of a motorcycle crash over time while also allowing for the modeling of multiple events. The average response rate for the four assessments was 92%. The adjusted relative hazard (RH) for students living in the rural as opposed to the urban area for crashes was 1.67 at the beginning of the study but decreased to 0.66 by the end. Past motorcycle crash history, number of riding days, average riding distance, risk-taking level, alcohol consumption, and traffic violations were all significantly associated with an increased risk of being involved in a crash. Conversely, increasing age, riding experience, and automobile licensure were related to a decreased risk of crashing. Furthermore, helmet use was not independently related to the risk of crashing. In conclusion, a high-risk group predisposed to involvement in a motorcycle crash, including both non-injury and injury-related crashes, can be identified using selected risk factors for crash prevention among young riders.

Accidents, Traffic↗

PubMed2003

Factors associated with severity of motorcycle injuries among young adult riders.

STUDY OBJECTIVE: A cohort of 4,729 junior college students in Taiwan was studied to determine risk factors for increased severity of motorcycle injuries. METHODS: Crash characteristics were collected by using self-administered questionnaires soon after a student was involved in a motorcycle crash. The proportional odds model with generalized estimating equations, with correlated ordinal responses for collisions categorized into not injured, mildly injured, and severely injured categories, was used to determine the odds of injury severity. RESULTS: A total of 1,889 motorcycle crashes involving 1,284 persons occurred over a 20-month period from November 1994 to June 1996. There were 1,339 noninjuries, 474 mild injuries, and 76 severe injuries. The adjusted odds ratio (OR) of rural to urban roads having a greater level of injury severity was 1.64. Compared with noncollisions, collisions with a moving car (adjusted OR=1.76), a parked car (adjusted OR 1.90), or another stationary object (adjusted OR=2.31) increased the odds for a greater level of injury severity. Riders using Sanyang (adjusted OR=1.63) and Yamaha (adjusted OR=1.39) motorcycles had greater odds of being involved in a crash with a greater level of injury compared with those riding Kymco motorcycles. Darkness (adjusted OR=1.65) and greater speeds (adjusted OR=1.63 to 4.69) also increased the odds of greater injury severity. CONCLUSION: At the time of motorcycle crashes, factors such as being on rural roads, collisions with a heavier object, some motorcycle makes, darkness, and greater speeds increased the severity of motorcycle injuries among these young adult riders.

Accidents, Traffic↗

PubMed2002

Assessing chronic disease progression using non-homogeneous exponential regression Markov models: an illustration using a selective breast cancer screening in Taiwan.

Previous research on estimation of the progression of chronic disease, from the normal preclinical screen-detectable phase (PCDP) to the final clinical phase, has usually assumed constant transition rates and has rarely addressed how relevant covariates affect multi-state transitions. The present study proposes two non-homogeneous models using the Weibull distribution and piecewise exponential model, together with covariate functions of the proportional hazard form, to tackle these problems. We illustrate the models by application to a selective breast cancer screening programme. The results of the Weibull model yield estimates of scale and shape parameters for annual preclinical incidence rate as 0.0000058 (SE=0.0000019) and 2.4755 (SE=0.1153), the latter being significantly higher than 1. Annual transition rate was estimated as 0.3153 (SE=0.1385). Relative risks for the effects of late age at first pregnancy (AP) and high body mass index (BMI) on preclinical incidence rate were 1.98 and 2.59, respectively. The corresponding figures on the transition from the PCDP to clinical phase were 1.56 and 1.99, respectively. Non-homogeneous Markov models proposed in this study can be easily applied to rates of progression of chronic disease with increasing or decreasing rates with time and to model the effect of relevant covariates on multi-state transition rates.

Adult↗

PubMed2002

Prognostic factors for the survival of Taiwanese breast cancer patients.

BACKGROUND: The incidence of breast cancer is increasing rapidly in Taiwan. Prognostic factors for survival in Taiwanese breast cancer patients have not been comprehensively studied. METHODS: Registry records of 979 newly diagnosed breast cancer patients who received initial therapy at National Taiwan University Hospital from January 1991 to December 1995 were linked to the national mortality file from 1991 to 1997 using the citizen ID of each patient. The effects of potential prognostic factors were assessed using Cox's regression model. Five-year survival rates of common characteristics were predicted according to the model. RESULTS: Among the 979 patients, 174 died within the 7-year study period (163 died from breast cancer). The overall 5-year survival rate was 81% (95% confidence interval, CI = 78-84%). The adjusted hazard ratio (HR) of mortality for patients aged at least 50 years versus patients aged less than 50 years was 1.49 (95% CI = 1.08-2.05); the HR of mortality for tumors of at least 5 cm in diameter versus those less than 2 cm was 2.45 (95% CI = 1.33-4.51); the HR of mortality for positive versus negative nodes was 3.65 (95% CI = 2.33-5.71); and the HR of mortality for pathology of infiltrating ductal carcinoma versus other types was 2.63 (95% CI = 1.32-5.27). Five-year survival rates for patients without node involvement were higher than 90% regardless of tumor size, while those for patients with positive nodes were significantly lower, except for patients with tumors of less than 2 cm in diameter. CONCLUSIONS: Patients who had a small tumor and involvement of fewer nodes, and who were younger, had a higher probability of survival. Node involvement was more important than tumor size in the prediction of survival.

Adult↗