106 children, who were consecutive referrals to a university affiliated Child and Adolescent Psychiatry Clinic in Shiraz, Iran, participated in this study. All of the children and adolescents were interviewed face to face by a board certified Child and Adolescent psychiatrist. In addition, at least one of their parents or caregivers was interviewed face to face as a collateral information resource.
The Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, DSM-IV diagnostic criteria was used to make psychiatric diagnoses . Interviews were conducted according to the Farsi version of the Schedule for Affective Disorders and Schizophrenia for School-Age Children .
Parents reported ADHD symptoms by completing the ADHD checklist of child symptom inventory-4 [14–16]. The ADHD checklist of child symptom inventory-4 includes 18 symptoms. The symptoms are categorized into two groups of inattentiveness and hyperactive/impulsivity symptoms. The inattentiveness symptoms category consists of 9 symptoms according to DSM-IV. The category of hyperactive/impulsivity symptoms consists of 9 symptoms according to DSM-IV as well. In fact, the symptoms are the DSM-IV diagnostic criteria. There is a 5-point Likert response scale for the symptoms. The responses ranged from "never," "sometimes," "often," to "almost always". Scores 0 and 1 were assigned to the categories of "never" and "sometimes", respectively. The categories of "often" and "almost always" were assigned to 2 and 3, respectively. The range of scoring for each of inattentiveness and hyperactivity-impulsivity categories was from 0 to 9. The Farsi version of this checklist has enough reliability, convergent and discrimination validity  and has been used in many studies [17–19]. The internal reliability of this checklist for ADHD-inattentive type, ADHD-Hyperactive impulsive type, and combined type of ADHD is 0.81, 0.85, and 0.83, respectively .
The four new items proposed by DSM-V to be added to ADHD diagnostic criteria were translated into Farsi and back translated into English by a bilingual child and adolescent psychiatrist and a psychologist. Every effort was made to preserve the concept of each symptom. After a pilot study on children referred to the clinic, the final version was used in the current study. The responses to these symptoms were in the Likert scale ranging from "never," "sometimes," "often," to "almost always".
The children and parents or caregivers gave their assent or informed written consent for voluntary participation in this study. This study was approved by the Ethics Committee of Shiraz University of Medical Sciences.
SPSS statistical software was used to analyze the data. A factor analysis with varimax rotation was conducted to examine the factor structure of the ADHD DSM-V symptoms. The Kaiser-Meyer-Olkin Measure and the Bartlett's test of sphericity were conducted. Internal consistency was examined using Cronbach's tests.
One-, two-, three-factor models of confirmatory factor analysis were also conducted using LISREL 8.54 software. The convergent and discriminative validity of ADHD symptoms were analyzed using Pearson's r correlation coefficient.
Another factor analysis was also conducted including the four newly proposed symptoms to examine item loading of the 13 symptoms of DSM-V derived hyperactivity- impulsivity symptoms. Here, the symptoms of inattentiveness were not included in the analysis. This analysis was conducted to examine whether the 13 items could be divided into two categories of hyperactivity and impulsivity.
Another factor analysis was conducted including the DSM-IV derived inattentiveness symptoms and the four new symptoms proposed in DSM-V. The symptoms of hyperactivity-impulsivity of DSM-IV were not included.