Xin Shi

A risk analysis based on a two-stage delayed diagnosis regression model with application to chronic disease progression

This paper presents a two-stage regression model for quantifying different stages of a disease progression with delayed diagnosis time and for identifying the risk factors associated with each stage. Conventional chronic disease progression studies reported replied on the assumption that the time of the confirmation of a disease state by diagnosis is the start time of this disease state. Clearly this will lead to biased estimates of progression since the disease state should have already occurred before the diagnosis, but the true occurrence time is unknown. This later confirmation is called the delayed diagnosis in this paper and a delay-time modelling procedure is developed for the identification of the unknown stages of progression. A hazard-based regression model is also proposed for a further risk analysis. We apply the developed methods to hepatitis C data and the analysis shows that considering the delayed diagnosis significantly improved the model fit in comparison with the conventional model. We also find that the risk factors associated with each stage are more significant, particularly in the second stage of progression, than those based on the conventional model. We conclude that such delayed phenomena in diagnosis should be taken into account when modelling the chronic disease progression process and conducting related risk analysis.

Impact of delayed diagnosis time in estimating progression rates to hepatitis C virus-related cirrhosis and death

Delay of the diagnosis of hepatitis C virus (HCV), and its treatment to avert cirrhosis, is often present sincethe early stage of HCV progression is latent. Current methods to determine the incubation time to HCV-related cirrhosis and the duration time from cirrhosis to subsequent events (e.g. complications or death) used to be based on the time of liver biopsy diagnosis and ignore this delay which led to an interval censoring for the first event time and a double censoring for the subsequent event time. To investigate the impact of this delay in estimating HCV progression rates and relevant estimating bias, we present a correlated two-stage progression model for delayed diagnosis time and fit the developed model to the previously studied hepatitis C cohort data from Edinburgh. Our analysis shows that taking the delayed diagnosis into account gives a mildly different estimate of progression rate to cirrhosis and significantly lower estimated progression rate to HCV-related death in comparison with conventional modelling. We also find that when the delay increases, the bias in estimating progression increases significantly.

Students' Production of Curricular Knowledge: Perspectives on Empowerment in Financial Capability Education.

The aim of this article is to extend our understanding of the relationship between knowledge of personal finance and empowerment. The analysis is based on interview data obtained as part of a longitudinal study of students, aged 16–19, who completed a financial capability course in the UK. The analysis presents a set of cultural models or storylines implied in student discourse about what it means to be financially capable. Possibilities for empowerment are interpreted from these cultural models with implications for how we define the boundaries of financial capability education. References to empowerment in terms of having a voice and feeling confident to make consumer decisions and to advise others in matters of finance were common across the interview data. However, a form of knowledge and empowerment that positioned students not as aware consumers but as individuals with a critical awareness of financial and economic systems was less evident.

The life-course impact of smoking on hypertension, myocardial infarction and respiratory diseases

The objective of this study was to examine the impact of smoking on respiratory diseases, hypertension and myocardial infarction, with a particular focus from a life-course perspective. In this study, 28,577 males from a Chinese longitudinal survey were analysed. The effects of smoking on the risk of respiratory diseases, hypertension and myocardial infarction were assessed from a life-course perspective and a current view separately. No significant associations were found between smoking and the risk of incident respiratory diseases, hypertension and myocardial infarction in the group younger than 35. Among study participants aged between 36–55 and 56–80, smoking was positively associated with the risk of incident respiratory diseases, hypertension and myocardial infarction from the life-course perspective, and the risk increased with age. In contrast, the results from a current view showed inverse associations between smoking and the risk of the diseases mentioned above. Our findings highlight that it is essential to quantify the effects of smoking from a life-course perspective in future research and to suggest that smokers quit smoking as soon as possible, regardless of the temporary side effects of quitting.

Modelling Batting Strategy in Test Cricket

During the third innings, we suppose that the batting team selects a run-rate and target to optimise the match outcome probabilities. Outcome probabilities are calculated using a model for the outcome given the end of third innings position, and a model for the target set given the current position and the chosen run-rate. While the run-rate is not wholly in the control of the batting side, the approach described may allow a decision-maker to consider outcome probabilities if the team is able to bat the remainder of its third innings at a particular runrate. This can then indicate whether an aggressive or defensive batting strategy is desirable.