A Polytomous CD-CAT And Its Applied Researches

Depression is a mental disorder that is common on a global scale and is extremely harmful to individuals and the whole society,however currently the diagnosis of depression depends on a limited number of medical personnel and psychologists,the lack of human resource makes the diagnosis of depression very inefficient and a an effective and accurate diagnostic tool for large scale application is in need.CD-CAT not only retains the accuracy and short test length of traditional CAT but also is capable of judging each single symptom,which could be a great help for diagnosis.In this study,Sequential G-DINA model(hereafter called Seq-GDINA),a relatively new model is used in an attempt to build a CD-CAT for the diagnosis of depression,five kind of commonly used item selection strategy for dichotomous CD-CAT had been expended into polytomous version and their effect had been compared,an item bank for the diagnosis of depression is built and was tested among depression and normal subjects.The research indicated:(1)Monte Carlo simulation experiments show that Seq-GDINA apply to polytomous tests and performed well.SHE is generally the best among the five item selection strategies.It can keep the balance between keeping a short test length and ensuring a high accuracy.When the test length is fixed,CD-CAT using Seq-DINA model had high accuracy,but it requires high posterior probability as stopping rule to reach high accuracy when the test length is variable.(2)After the analysis of test items in the framework of cognitive diagnosis,a depression test bank containing 122 questions was built,which basically accords with the requirements of cognitive diagnostic measurement.(3)When the data of subjects answering the test was collected,the subjects was diagnosed using the whole item bank,then their process of taking a CD-CAT test was simulated and the agreement rate of two results was compared.Pattern match ration ofCD-CAT reached 0.860,Average attribute match ratio reached 0.976,the correlation between diagnosis results and the subjects’ score on CES-D,SDS and PHQ-9 was0.842,0.629 and 0.832 and was all significant(p<0.001).The average test length was21.636.It could be considered that the test has high accuracy and validity as well as short test length.(4)CD-CAT can provide detail symptom of every patients and tell the grade of depression according to the standard of ICD-10.There are 57 kinds of symptoms pattern among the subjects,for example,only 4 subjects are diagnosed as pattern“0000000000”,which means they had no symptom of depression.Different symptom between patients with same depression grade can be told.22.9% of subjects that had not been diagnosed as depression held a few symptoms.That means CD-CAT can be used for the diagnosis of depression and its symptom.(5)In addition to the diagnosis and classification of the individual patient’s symptoms,the data obtained from the results of the symptoms also has the potential to be used in other areas.For instance,among subjects that are not clinical depression patients,a large number of them possess the symptom of “ lack of interest or pleasure in daily activities” and “reduced thinking and attention”,which is worthy of attention and could be the key to the prevention of depression in this group.More than half of moderately depressed patients consider or commit suicide and require the attention of family members and medical personnel.