ABSTRACT
Objective To compare the effect of ARIMA models with and without covariates in predicting the number of HIV infections among young students in Dalian. Methods First, univariate correlation analysis was performed on the network, STD sequence and HIV sequence to understand whether there was a correlation and lag relationship between them. Secondly, variables with the strongest correlation and predictive value and HIV infection numbers were used as the baseline data to establish an ARIMA model with covariates and a general ARIMA model without covariates, and to predict the HIV number from 2019 to 2021. The average absolute errors were used as evaluation indexes to compare the prediction effects of the two models. Results A total of 841 cases of HIV infection among young students were reported in Dalian from 2013 to 2021. The results of univariate correlation analysis showed that the search index of the keyword AIDS in the Baidu Index in a given month from 2013 to 2019 was significantly positively correlated with the number of HIV infections in that month (r=0.302, P=0.006), and gonorrhea was negatively correlated with the number of HIV infections with a lag of 2 months (r=-0.250, P =0.024). Using gonorrhea incidence number and HIV infection number as the basic data, an ARIMA model with covariates and a general ARIMA model without covariates were established to predict the number of HIV infection among young students from 2019 to 2021, and the average absolute errors were 17.621% and 66.17%, respectively. Conclusion Compared with the general ARIMA model without covariates, the ARIMA model based on the combined use of STD incidence and HIV infection is more suitable for predicting the number of HIV infections among young students in Dalian, but the average absolute error of the model is still large, which needs further improvement in the future research.
ABSTRACT
Objective To explore the relationship between the body mass index and health-related quality of life(HRQoL) of young students aged 18～25 years old. Methods 4696 students aged 18～25 years old from nine provinces and municipalities (Jiangsu, Anhui, Gansu, Qinghai, Fujian, Boijing, Jilin, Jiangxi and He'nan) were investigated. The HRQoL of students with different body mass index were compared with rank sum test and lo-gistic regression analysis. Results Obesity and underweight students scored lower in both physical component and mental component scores of SF-36. Compared to students with normal weight, odds ratios (ORs) of impaired HRQoL among obesity students significantly increased in both physical domain (OR=1.86) and mental domain (OR=1.90), while OR of impaired HRQoL among underweight students significantly increased only in physical domain(OR=1.21). Analysis for boys and girls scparately,OR of impaired HRQoL increased in physical domain among underweight boys(OR=1.37), and increased in mental domain among overweight girls(OR=3.85). Con-clnsion Different body mass index have different impact on young students' HRQoL. Both obesity and trader-weight could reduce HRQoL. But obesity have more impact on girls' mental domain than boys, and underweight have more impact on boys' physical domain than girls.