Abstract The issue of multimorbidity in children and adolescents is becoming increasingly prominent, but there is no consensus on the definition of multimorbidity. As research deepens, issues related to the comparability and standardization of relevant findings are gradually emerging. As a solution, a systematic review of both domestic and international research on multimorbidity is conducted, and a classification system for defining the concept of multimorbidity is proposed, offering more convenient conditions for the advancement of future research and cross study exchange.

Objective: To analyze the association and dose response relationship between physical activity and inflammatory markers in college students, so as to provide a reference for promoting cardiometabolic health in college students. Methods: A cluster random sampling method was used to select 747 college students from two universities in Hefei, Anhui Province and Shangrao, Jiangxi Province from April to May 2019. Physical activity was assessed by using the International Physical Activity Questionnaire-Short Form (IPAQ-SF), and peripheral blood was collected to detect plasma inflammatory factor levels [including hypersensitive C reactive protein (hsCRP), interleukin-10 (IL-10), interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α)]. The differences between the groups were compared by using the χ 2 test and the Kruskal-Wallis rank sum test, and the association between physical activity and inflammatory markers was analyzed by using the Generalized Linear Model. The dose response relationship between physical activity and inflammatory markers was analyzed using the Restricted Cubic Spline Model. Results: The proportions of low physical activity, moderate physical activity, and high physical activity groups of college students were 15.9%, 53.7% and 30.4%, respectively. The levels of hsCRP, IL-10, IL-1β, IL-6 and TNF-α in the high physical activity group were 0.38(0.21, 1.10)mg/L, 70.74(47.90, 116.43)pg/mL, 1.75(1.21, 2.64)pg/mL, 4.33(2.93, 6.82) pg/mL , 5.27(3.89, 7.30)pg/mL,the levels in the low physical activity group were 0.80(0.31, 1.30)mg/L, 73.88 (47.90, 124.24)pg/mL, 1.88(1.42, 2.81) pg/mL, 4.82 (3.64, 6.67) pg/mL, 5.63 (4.34, 7.62)pg/mL, the levels in the moderate physical activity group were 0.63(0.25, 1.30)mg/L, 89.78(58.21, 127.65)pg/mL, 2.21(1.59, 3.27)pg/mL, 5.15( 3.72 , 7.72)pg/mL, 5.87( 4.63 , 8.00)g/mL, and the differences were statistically significant ( H=10.66, 11.38, 27.79, 14.13, 9.44, P <0.05). After adjusting for variables such as gender, body mass index, smoking, alcohol consumption and health status, the results of Generalized Linear Model showed that compared with the high physical activity group, the low physical activity group ( OR=2.20, 95%CI = 1.46- 3.31) and the moderate physical activity group ( OR=1.65, 95%CI =1.22-2.25) were more likely to have high levels of hsCRP, and the moderate physical activity group was more likely to have high levels of IL-1β ( OR=1.85, 95%CI =1.36-2.51), IL-6 ( OR=1.44, 95%CI =1.06-1.96), and TNF-α ( OR=1.43, 95%CI =1.05-1.94) ( P <0.05). The Restricted Cubic Spline Model showed that there was no linear dose response relationship between the time of moderate to vigorous physical activity weekly and IL-10, IL-6, II-1β, and TNF-α ( P <0.05). Conclusion There is an association between physical activity and inflammation in college students, and moderate to high intensity per week could reduce inflammation levels to promote cardiometabolic health in college students.

Objective: To describe the association of different sleep characteristics and cardiometabolic risk among college students, so as to provide reference for health promotion of college students. Methods: By random cluster sampling method, a questionnaire survey and physical examination including blood pressure, waist circumference and blood lipid indicators, which were conducted in April and May of 2019 among a total of 1 179 college students from the first grade in two universities in Hefei City of Anhui Province and Shangrao City of Jiangxi Province. A total of 729 college students with valid questionnaires were included into analysis. The Pittsburgh Sleep Quality Index (PSQI) and Insomnia Severity Index (ISI) were used to investigate sleep behavior, and the Morning And Evening Questionnaire-5 (MEQ-5) was used to investigate sleep characteristics. The cardiometabolic risk score was derived using the sum of the standardized sex specific Z scores of waist circumference, mean arterial pressure, HDL cholesterol (multiplied by -1), triglycerides, and insulin resistance index. The rank sum tests were used to compare differences in cardiometabolic risk scores across demographic characteristics. Generalized linear models were used to compare the association of different sleep characteristics with cardiometabolic risk scores among college students. Results: The average cardiovascular metabolic risk score of college students was -0.32(-2.03, 1.58). There were statistically significant differences in cardiovascular metabolic risk scores among college students in variables such as smoking, health status, and physical activity levels ( t/F=-3.41, 12.88, 51.07, P <0.01). The results of the generalized linear model showed that nighttime preference ( B=1.89, 95%CI =1.02-3.49), insomnia symptoms ( B=3.25, 95%CI =1.79-5.90), and short or long sleep duration ( B=1.92, 95%CI =1.21-3.05) were positively correlated with the cardiovascular metabolic risk score of college students ( P <0.05). Conclusions Poor sleep patterns among college students are positively correlated with the risk of cardiovascular metabolism. The sleep behavior of college students should be actively changed to reduce the risk of cardiovascular disease.

Objective: To describe the prevalence and the association of sleep quality trajectory, social jetlag and comorbid symptoms of anxiety and depression among college students, in order to provide a theoretical basis for improving the comorbid symptoms of anxiety and depression in college students. Methods: A questionnaire survey was conducted among 1 135 college students from two universities in Shangrao, Jiangxi Province and Hefei, Anhui Province from April to May 2019, and were followed up once every one year for a total of three times, with a valid sample size of 1 034 individuals after matching with the baseline survey. A selfassessment questionnaire was used to investigate the social jetlag of college students, the Generalized Anxiety Disorder-7 (GAD-7) and Patient Health Questionnaire 9 (PHQ-9) were used to evaluate anxiety and depression symptoms, respectively, while the Pittsburgh Sleep Quality Index (PSQI) was used to assess sleep quality. College students with GAD-7 score ≥5 and PHQ-9 score ≥5 were defined as having comorbid anxiety and depression symptoms. Latent class growth model (LCGM) was employed to analyze the sleep quality trajectory of college students, and binary Logistic regression was used to analyze the relationship between social jetlag, sleep quality trajectory and comorbid symptoms of anxiety and depression. Results: The detection rate of comorbid symptoms of anxiety and depression among college students was 16.9%, and the detection rate of social jetlag ≥2 h was 13.8%. The sleep quality showed an overall improvement trend, and the two trajectories were good sleep quality (81.6%) and poor sleep quality (18.4%). Binary Logistic regression model showed that poor sleep quality and social jetlag ≥2 h were positively correlated with comorbid symptoms of anxiety and depression (OR=5.94, 1.84, P<0.05). Conclusions Poor sleep quality and social jetlag ≥2 h in college students increase the risk of comorbid symptoms of anxiety and depression. Early screening and intervention of sleep quality and reduction of social jetlag are crucial for enhancing the mental health of college students.

Objective: To explore the current status and associated factors of bullying behavior among middle school students in Shanghai, so as to provide a reference basis for carrying out bullying intervention work. Methods: From May to June 2021, a stratified cluster sampling method was used to select 19 000 middle school students from 63 schools in 16 districts of Shanghai, and the Shanghai Youth Health Risk Behavior Survey Questionnaire was used to conduct an anonymous questionnaire survey of enrolled students. Chi square test and binary Logistic regression analysis were employed to investigate the associated factors of bullying among middle school students. Results: The prevalence of bullying behaviors in Shanghai was 15.5%, with males and junior high school students exhibiting the higher reporting rate(19.5%,17.2%). And malicious teasing or name calling had the highest reported rate at 9.4%. The results of binary Logistic regression analysis showed that fighting ( OR =5.02), attempting to smoke ( OR =3.22), having a feeling of sadness and hopelessness ( OR =2.50) and getting drunk( OR =1.72) were positively associated with bullying behavior among middle school students. Fighting ( OR =3.83-8.97), attempting to smoke ( OR =2.92-5.52), having a feeling of sadness and hopelessness ( OR =2.40-4.34), and getting drunk ( OR =1.66-2.34) were positively correlated with 6 forms of bullying (malicious teasing or name calling, intentionally damaging someone else s belongings, deliberately excluding someone from activities or isolating someone, threatening or intimidating others, hitting, kicking, or pushing someone, and verbally harassing or attacking someone online) ( P <0.05). Conclusions Bullying behavior of middle school students in Shanghai primarily presents as verbal harassment. In the future, greater attention should be directed towards bullies, and it should recognize potential hazards promptly and implement precise intervention measures.

Objective To investigate the clinical application value of wrist joint ulnar deviation supination 45° palmar oblique posi-tion in the diagnosis of scaphoid waist fracture and displacement.Methods The imaging and clinical data such as digital radiography(DR),CT of 93 wrist joint trauma patients were analyzed.The four position views including wrist joint anteroposterior+lateral view,scaphoid position,wrist joint ulnar deviation supination 45° palmar oblique position,scaphoid position+wrist joint ulnar devia-tion supination 45° palmar oblique position were analyzed by three readers.The consistency of the evaluation among different readers and the diagnostic efficiency of the diagnosis of scaphoid fracture and displacement were compared.Results The inter-observer agreement,sensitivity,specificity,accuracy,and other diagnostic efficiency of scaphoid waist fracture and displacement was evaluated,wrist joint ulnar deviation supination 45° palmar oblique position+scaphoid position and wrist joint ulnar deviation supination 45° palmar oblique position were better than those of scaphoid position and wrist joint anteroposterior+lateral view.The combination of wrist joint ulnar deviation supination 45° palmar oblique position+scaphoid position obtained the best diagnostic efficiency.Conclusion The wrist joint ulnar deviation supination 45° palmar oblique position shows the long axis of the scaphoid,which has a high diagnostic efficiency in the diagnosis of scaphoid waist fracture and displacement and would be used as a useful supplement to other scaphoid imaging.

Objective This study aimed to estimate the therapeutic effects of preformed metal crown(PMC)and pre-fabricated zirconia crowns(ZC)on decayed primary morals in children,as well as to analyze the possible influencing fac-tors.Methods A retrospective cohort study was performed on the data of 192 patients(aged 3 to 8)in the Stomatologi-cal Department of Shenzhen Children's Hospital from October 2021 to December 2021.The decayed mandibular first molars were selected and restored by vital-pulp therapy followed by PMC and ZC,including 96 cases(96 caries)in the PMC group and 96 cases(96 caries)in the ZC group.Oral clinical examination was performed at 3 months,1 year,and 2 years after treatment,overwiewing the clinical therapeu-tic effects and periodontal status of PMC and ZC groups,as well as recording the crown integrity,gingival index(GI),probing bleeding index(BI),plaque index(PLI)and various prosthetic indices.Results No significance differences existed in the periodontal status of PMC and ZC groups at 3 months,1 year,and 2 years after treatment(P>0.05).However,the GI,BI,and PLI in the PMC group were higher than those in the ZC group at 3 months,1 year,and 2 years after treatment,and the difference was dramatically signifi-cant(P<0.05).No significances difference existed in various prosthetic indices(P>0.05),as well as in the GI,BI,and PLI,between the two groups(P>0.05).No significant differences existed in various prosthetic indices between genders after PMC restoration(P>0.05).The scores of girls in various prosthetic indices after ZC restoration were higher than those of boys(P<0.05).Pearson correlation analysis indicated an inverse correlation between age in the PMC group and the GI,BI,PLI,and FDI indices(P<0.01),rather than in the ZC group(P>0.05).Conclusion PMC and ZC can be ap-plied to restore deciduous molar caries.The periodontal status of deciduous teeth in ZC group was superior to that in the PMC group.The periodontal status of deciduous teeth in PMC group may be stable with increased age.

Objective: To understand the relationship between stress and Internet addiction among middle school students in Shanghai, so as to provide a scientific basis for promoting students mental health and preventing Internet addiction. Methods: From May to June 2021, a stratified random cluster sampling method was used to select 6 123 middle and high school students in Shanghai for health risk behavior monitoring. Daily Stressors Evaluation Scale for Urban Secondary School Students was used to evaluate students' stress, and the Internet Addiction Test compiled by Young was used to evaluate students Internet addiction. The correlation between student stress and Internet addiction was analyzed by Kruskal-Wallis H test , Chi square test and multiple Logistic regression. Results: Total stress score of middle school students in Shanghai was 24 (12, 39), academic stress score was 8 (5, 13), physical and psychological stress score was 6 (2, 10), interpersonal stress score was 5 (1, 9), and family stress score was 4 (1, 8). The detection rate of Internet addiction was 4.7%. Multivariate Logistic regression analysis showed that the risk of Internet addiction among middle school students with high levels of stress was 8.05 times(95% CI =4.59-14.12) that of students with low levels of stress( P <0.05). The risk of Internet addiction among middle school students with high levels of academic stress, physical and psychological stress, interpersonal stress and family stress was 5.98(95% CI =3.69-9.70), 6.92(95% CI =4.03-11.88), 4.85(95% CI =3.11-7.55), and 4.18(95% CI =2.73-6.40) times that of students with low levels of stress, respectively( P <0.05). Conclusion The academic stress, physical and psychological stress, interpersonal stress, and family stress among middle school students can all lead to an increased risk of Internet addiction.

Objective: The study aimed to describe the prevalence of mobile phone use and depressive symptoms and to examine the bidirectional associations between the two among college students, providinb evidence for mental health promotion among college students. Methods: A longitudinal study with follow up at 6 month intervals was conducted in 1 135 students from 2 universities in Hefei, Anhui Province and Shangrao, Jiangxi Province who were selected between April and May 2019. The last follow up was conducted between April and May 2021 based on questionnaire survey, and 999 valid participants were obtained after matching. The self designed questionnaire was used to investigate the duration of cellular phone use and use of cellular phone functions among college students. The Self rating Questionnaire for Adolescent Problematic Mobile Phone Use (SQAPMPU) and the Patient Health Questionnaire-9 (PHQ-9) were used to assess cellular phone dependence and depressive symptoms among college students. Pearson correlation analysis was used to examine the correlation between cellular phone use behavior and depressive symptoms at baseline and 2 years later; linear regression model was used to analyze the linear association between cellular phone use behavior and depressive symptoms scores; autoregressive cross lagged model was used to analyze the bidirectional associations between cellular phone use behaviors and depressive symptoms among college students over time. Results: The prevalence of mobile phone dependence and depressive symptoms among college students at baseline were 24.3% and 42.4%, respectively. The mean duration of mobile phone use among college students at baseline and the 2 year follow up were (2.84±0.90)h/d and (2.02±1.05)h/d, respectively; the mean scores of mobile phone dependence were (23.30±9.00) and (23.29±10.45), respectively; the mean scores of mobile phone function use were (30.12±6.66) and (29.12±7.27), respectively; and the mean scores of depressive symptoms were (4.51±4.76) and (2.61±4.40), respectively. Pearson correlation analysis showed there were significant positive correlations between duration of cellular phone use, cellular phone dependence, use of cellular phone functions at baseline or 2 years later and depressive symptoms 2 years later( r =0.08-0.50, P <0.05). Linear regression models showed a significant positive association between cellular phone dependence at baseline and depressive symptoms ( β=0.26, 95%CI =0.23-0.29) at baseline and 2 years later ( β=0.12, 95%CI =0.09-0.15). Autoregressive cross lagged models showed that cellular phone dependence at baseline positively predicted depressive symptoms 2 years later ( β =0.04) and depressive symptoms at baseline positively predicted cellular phone dependence 2 years later( β =0.23)( P <0.05). Conclusion There was a bidirectional association between cellular phone dependence and depressive symptoms among college students. Reducing cellular phone dependence is of positive significance for improving college students mental health.

Objective: To develop the Assessment of Smartphone Multitasking for Adolescents (ASMA) and evaluate its reliability and construct validity, so that to provide an evaluation tool for relevant epidemiological studies. Methods: Based on literature review, expert based judgement, and group discussion, the self administered ASMA identified 3 dimensions named smartphone activities and non-media activities multitasking, smartphone activities and other media activities multitasking, and smartphone functional use multitasking, which initially included 27 items. From October to December 2021, 5 566 college students were selected from 7 regions, including Liaoning, Shanxi, Henan, Shanghai, Chongqing, Shenzhen, and Yunnan by multi stage cluster sampling method, and item analysis, factor analysis, and reliability evaluation were used to screen items and evaluate reliability and validity. Results: The final version of AMSA contained 3 dimensions covering 26 items. The variance cumulative contribution rate was 59.63 %. The internal consistency test showed that Cronbach s alpha coefficient for the questionnaire was 0.944, and ranged from 0.838 to 0.928 for each dimension. The split half coefficient of the questionnaire was 0.849 and ranging from 0.781 to 0.874 for each dimension. The results of confirmatory factor analysis showed that the root mean square error of approximation (RMSEA), comparative fit index (CFI), and Tucker Lewis index (TLI) of the questionnaire were 0.068, 0.901, and 0.891, respectively, which had which had a good fitting degree. The results of Pearson correlation analysis showed that the criterion validity of the questionnaire was good ( r=0.206-0.351, P <0.01). Conclusion The ASMA is consistent with the evaluation standard of psychometrics and can be used as an assessment tool to evaluate smartphone multitasking behaviors in adolescents.