Risk behaviors contributing to recent serious unintentional injuries among school-going adolescent boys in Kolkata: Application of zero-inflated count model

Background: Unintentional injuries have become a major noncommunicable disease burden, especially among the adolescents. Objective: The current study was conducted to estimate the effect of different aspects of daily activities of adolescence for sustaining serious unintentional injuries in the past 1 year. Methods: A cross-sectional survey with multistage sampling with validated pretested questionnaire was done among the school-going adolescent boys in Kolkata. Poisson regression was used to model the counts of serious injuries. To account for the excess of zero in the outcome, zero-inflated Poisson regression was performed. Results: Among the participants, 73.5% did not report any serious unintentional injury sustained in the past 1 year, 11.9% reported to have sustained serious unintentional injury once in the past 1 year, and rest had more than one count. Statistically significant higher chance of sustaining an episode of injury was found among frequent users of motorbike (incidence rate ratio [IRR]: 1.183), frequently walking on roads (IRR: 1.910), and frequently crossing major roads on bicycle (IRR: 2.181) were observed. A statistically significant protective rate ratio was also obtained for those frequently obeying traffic signals while crossing roads (IRR: 0.493) and frequent users of bicycles (IRR: 0.384). Significantly lower rate ratio for sustaining a serious injury was observed with frequently getting into fight at home (IRR: 0.343) and getting beaten up at school (IRR: 0.595). Conclusions: The study revealed traveling in a car and obeying traffic rules were protective from sustaining serious injury. However, walking and participation in sports appeared to be risky, especially for sustaining another episode of serious injury.

Factors associated with smoking cessation attempts in male current smokers in rural area of Shandong province / 中华流行病学杂志

Objective To explore the influencing factors for the smoking cessation attempts in male current smokers.Methods This cross-sectional study was conducted in nine villages selected from three counties (Pingyin,Junan and Liangshan) of Shandong province in August,2010 through household questionnaire survey in villagers aged ≥ 15 years to collect the information about current smokers demographic characteristics and smoking-related behaviors.A hurdle count data model was used to assess factors associated with the times of past smoking cessation attempts.Results Among 1 798 male current smokers,29.53％ had at least one smoking cessation attempt.Smokers who were married (3=0.705,P=0.002),had high educational level (β=0.214,P=0.026) and had higher level of awareness of smoking risks (β=0.237,P=0.009) were more likely to have smoking cessation attempt.Young age at smoking initiation (3 =-0.167,P=0.035) and higher level of awareness of smoking risks (β =0.146,P=0.020) were associated with increased smoking cessation attempts.Conclusions Less male current smokers had smoking cessation attemps in rural area in Shandong.The factors influencing smoking cessation attempt varied.It is necessary to conduct targeted intervention according to the smokers' smoking cessation experience.

Factors associated with smoking cessation attempts in male current smokers in rural area of Shandong province / 中华流行病学杂志

Objective To explore the influencing factors for the smoking cessation attempts in male current smokers.Methods This cross-sectional study was conducted in nine villages selected from three counties (Pingyin,Junan and Liangshan) of Shandong province in August,2010 through household questionnaire survey in villagers aged ≥ 15 years to collect the information about current smokers demographic characteristics and smoking-related behaviors.A hurdle count data model was used to assess factors associated with the times of past smoking cessation attempts.Results Among 1 798 male current smokers,29.53％ had at least one smoking cessation attempt.Smokers who were married (3=0.705,P=0.002),had high educational level (β=0.214,P=0.026) and had higher level of awareness of smoking risks (β=0.237,P=0.009) were more likely to have smoking cessation attempt.Young age at smoking initiation (3 =-0.167,P=0.035) and higher level of awareness of smoking risks (β =0.146,P=0.020) were associated with increased smoking cessation attempts.Conclusions Less male current smokers had smoking cessation attemps in rural area in Shandong.The factors influencing smoking cessation attempt varied.It is necessary to conduct targeted intervention according to the smokers' smoking cessation experience.

Using zero inflated models to analyze dental caries with many zeroes.

Aim: The study aimed to analyze and determine the factors associated with dental caries experience contains many zeros by zero inflated models. Design: A cross sectional design was employed using clinical examination and questionnaire with interview method. Materials and Methods: A study was conducted during March-August 2007 in Dharwad, Karnataka, India, involved a systematic random samples of 1760 individuals aged 18-40 years. The dental caries examination was carried out by using DMFT index (i.e. Decayed (D), Missing (M), Filled (F)). The DMFT index data contains many zeros were analyzed with Zero Inflated Poisson (ZIP) and Zero Inflated Negative Binomial (ZINB) models. Results: The study findings indicated, the variables such as family size, frequency of brushing and duration of change of toothbrush were positively associated with dental caries. But the variable the frequency of sweet consumption is negatively associated with dental caries experience in Zero Inflated Poisson (ZIP) and Zero Inflated Negative Binomial (ZINB) models. Conclusions: The ZIP model is a very good fit over the standard Poisson model and the ZINB is the better statistical fit compared to the Negative Binomial model. The Zero Inflated Negative Binomial model is better fit over the Zero Inflated Poisson model for modeling the DMF count data.

Handling Overdispersion in Mortality Data in Time-Series Epidemiologic Research Using SAS Software

Analysis of count event data such as mortality cases, were often modelled using Poisson regression model. Maximum likelihood procedures were used by using SAS software to estimate the model parameters of a Poisson regression model. However, the Negative Binomial distribution has been widely suggested as the alternative to the Poisson when there is proof of overdispersion phenomenon. We modelled the mortality cases as the dependent variable using Poisson and Negative Binomial regression and compare both of the models. The procedures were done in SAS by using the function PROC GENMOD. The results showed that the mortality data in Poisson regression exhibit large ratio values between deviance to degree of freedom which indicate model misspecification or overdispersion. This large ratio was found to be reduced in Negative Binomial regression. The Normal probability plot of Pearson residual confirmed that the Negative Binomial regression is a better model than Poisson regression in modelling the mortality data. The objective of this study is to compare the goodness of fit of Poisson regression model and Negative Binomial regression model in the application of air pollution epidemiologic time series study by using SAS software.