| 1.ObjectiveInsomnia is one of the most common sleep disorders characterized by frequent and persistent difficulty in falling asleep or difficulty in sleep maintenance and leads to a lack of sleep satisfaction.The prevalence rate is 10 to 15%1.It has obvious damage to the awakening of daytime function,such as fatigue,low motivation,irritability,depression,attention and memory decline,and lethargy,and is proved to have many kinds of somatic diseases and mental disorders of prodrome and maintain factors2.The evaluation tool for insomnia can be divided into two categories:objectivity and subjectivity.Polysomnography(PSG)is the most commonly used objective assessment tool to assess the pathophysiological status of sleep structure and sleep.However,the subjective feeling of sleep is not necessarily consistent with the objective data of PSG,so the subjective assessment tool-scale is also very important,which can be verified and supplemented with PSG data.The advantage of the scale is that it is easy to use,and the evaluation results are intuitive,saving manpower effectively and improving working efficiency.In Chinese literature,Pittsburgh sleep quality index scale(Pittsburgh sleep quality index,PSQI)is widely used in the evaluation of insomnia,but PSQI for comprehensive assessment of the condition of sleep quality and sleep,insomnia is not assessment scale.Epworth Sleepiness Scale(ESS)is also widely used in Chinese literature to assess the Sleepiness of insomnia patients to assess the damage of daytime function.Compared with the PSQI and ESS,Insomnia,severe Index scale(Insomnia Severity Index,ISI)is targeted to evaluate the Severity of Insomnia,but the ISI seldom applied in the Chinese literature,and the Chinese version of the reliability and validity is not assessed.Since 1993,the ISI has been translated into many languages,has been widely used in the world scope,in different age stages and each population(sleep disorders,mental disorders,cancer,etc.)in all showed good reliability and validity5,6.Therefore,this study will assess the reliability and validity of Chinese version Insomnia Severity Index(ISI)in students of technical schools.2.Methods2.1 Subjects2.1.1 Participants:All the new students of Guangzhou Baiyun Industry and Commerce Senior Technician School enrolled in September,2014 were selected.At the beginning of the study,they had to fill out a paper informed consent.2.2 MeasurementsAmongst 3969 students of technical school,their insomnia,sleep quality,daytime sleepiness,anxiety,and depression were assessed by the Insomnia Severity Index(ISI),Pittsburgh sleep quality index(PSQI),Epworth Sleepiness Scale(ESS),Self-Rating Anxiety Scale(SAS),Back Depression Inventory(BDI),and their socioeconomic characteristics were collected simultaneously.Age,gender,body mass index(BMI),health status,only child or not,residence,family income,father’s education level,mother’s education level.2.3 ProcessThe initial survey was conducted in October 2014,including the Chinese version of ISI,PSQI,ESS,SAS,BDI and social demographic data.The researchers introduced the purpose of this survey to the head of the school and the head teacher,so that students can get timely answers to the questions they did not understand in the process.A total of 4,733 questionnaires were issued,and 3,969 valid questionnaires were obtained(83.9%).Nine months later,2915 students(73.4%)were was assessed by ISI again.2.4 Statistic analysisStatistic analysis were conducted by software SPSS 18.0.General conditions of subjects were described using frequency,mean and standard deviation.T test was used to compare the measurement data with normal distribution.Categorical variables were compared in two groups by chi-square test.And numerical variables were compared in two groups by t test if normal otherwise by Mann-Whitney U test.Bonferroni was used in multiple comparison after signficant ANOVA.An exploratory factor analysis was conducted for the Chinese version of ISI through the Kaiser-meyer-olkin(KMO)test,Bartlett’s sphericity test and the maximal variance orthogonal rotation.Reliability was described by Chronbach’ α and Spearman Brown split-half reliability.Correlation of variables were tested by sprearman correlation test.P<0.05 was statistically significant in the statistical test.3.Results3.1 social demographic dataPre-assessment were conducted in October,2014 on all the new students of Guangzhou Baiyun Industry and Commerce Senior Technician School enrolled in 2014.Totally 4733 questionnaires were released and 4533(95.8%)were taking back.46 questionnaires missed more than 30%data and eight were unfinished which were deemed as invalid questionnaire.4479 questionnaires(94.6%)were valid.535(12%)subjects were randomly reassessed and 514 questionnaires(91.6%)were valid.The initial survey of 3,969 subjects was based on adolescents(17.9 ± 3.1[15-24]years old)and male(3211[80.9%]boys and 758[19.1%]girls).Their Body Mass index(BMI)was generally in the normal range(20.21 ±3.22).The vast majority of students are in good health(98.0%),non-only children(82.2%),few from the city(6.8%),and their parents’ education level is lower(education<10%).The social demographic data of 2915 retest subjects(2915/3969,73.4%)were similar to those of the initial test subjects,and there was no statistical difference.3.2 the distribution of the Chinese version of ISIThe skewness coefficient[skewness]is 1.095 and kurtosis is 1.493,which indicates the positive skewness distribution.According to Morin’s delimit,3,969 subjects were divided into 2,772 insomniacs(69.8%),991 mild insomniacs(25.0%),181 moderate insomniacs(4.6%)and 25 severely insomniacs(0.6%).3.3 validity of the Chinese version of ISI3.3.1 structure validityThe Chinese version of the ISI tends to be single factor structure,the KMO statistical value is 0.865,and the P value of Bartlett spherical test is<0.001.The range of each item load of the single-factor model with orthogonal rotation of maximal variance is 0.617-0.797,and the variance interpretation value is 52.1%.3.3.2 discriminant validityAs gradually increased the severity of insomnia,four groups(no sleepless,mild insomnia insomnia,moderate and severe insomnia)ESS,SAS scores and total score of BDI score are gradually increasing,while moderate ESS score between insomnia and severe insomnia and SAS scores showed no statistical differences.In addition,the total score of PSQI in the four groups showed no increasing trend.On the other hand,there is no correlation between PSQI scores and ISI scores,but there is significant correlation(P<0.001)between ISI and the other scores include ESS score,SAS scores and BDI score,and there is significant correlation between the total scores of PSQI and above scores(P<0.05).ISI had higher correlation with ESS,SAS,and BDI than PSQI.3.4 reliability of the Chinese version of ISI3.4.1 homogeneity reliabilityThe relevant coefficients of the Chinese version of the ISI are 0.742,0.727,0.630,0.766,0.707,0.675,0.789,and the P value is less than 0.001.In addition,the Spearman Brown score of the scale was 0.753 and the Chronbach alpha coefficient was 0.753 and 0.843 respectively.3.4.2 retest reliabilityBefore the end of the first year(about 9 months intervals),we carried on the Chinese version to all participants of ISI retested,2915(73.4%)completed the assessment,the Chinese version of the ISI scores and between each entry points in the preliminary survey and survey had no statistical difference.Spearmen correlation coefficient was 0.281-0.506,and Pearson correlation coefficient was 0.506,and P value was less than 0.001.Conclusion The ISI has good reliability and validity.Compared to PSQI,ISI had better correlation with daytime sleepiness,anxiety,and depression,so it might be suitable for adolescents. |
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