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BACKGROUND Differential item functioning (DIF) occurs when members from different groups respond differently to particular items in a health-related quality of life (HRQoL) questionnaire after controlling for underlying HRQoL construct. This study aimed to assess DIF in the SF-36 questionnaire and its effect on comparing HRQoL scores across patients on HD(More)
BACKGROUND Item response theory (IRT) is extensively used to develop adaptive instruments of health-related quality of life (HRQoL). However, each IRT model has its own function to estimate item and category parameters, and hence different results may be found using the same response categories with different IRT models. The present study used the Rasch(More)
UNLABELLED We provide the first reference values for bone mineral content and bone mineral density according to age and sex in Iranian children and adolescents. The prevalence of hypovitaminosis D was high, and levels of physical activity were low in our sample. Multiple regression analyses showed age, BMI, and Tanner stage to be the main indicators of bone(More)
BACKGROUND The aim of this study was to measure health related quality of life (HRQOL) in Iranian children with type 1 diabetes and to test the psychometric properties of the Persian version of the PedsQL™ 4.0 Generic Core Scales and the PedsQL™ 3.0 Diabetes Module. METHODS Participants were 94 children and adolescents diagnosed with type 1 diabetes for(More)
BACKGROUND The purpose of the study was to determine whether the Persian version of the KIDSCREEN-27 has the optimal number of response category to measure health-related quality of life (HRQoL) in children and adolescents. Moreover, we aimed to determine if all the items contributed adequately to their own domain. FINDINGS The Persian version of the(More)
Measurement equivalence is a necessary assumption for meaningful comparison of pediatric quality of life rated by children and parents. In this study, differential item functioning (DIF) analysis is used to examine whether children and their parents respond consistently to the items in the KINDer Lebensqualitätsfragebogen (KINDL; in German, Children Quality(More)
OBJECTIVE The paper presents a new trend of weight-for-height index of 2397 school children (1268 boys and 1129 girls) aged 6.5-11.5 years by sex in a representative sample from primary schools of Shiraz (Southern Iran) at an interval of 15 years (1988-2003) and its relation to the Center for Disease Control and Prevention (CDC) data (2000). METHODS The(More)
PURPOSE This study investigated the agreement of four anthropometric-based measurements including weight-for-height (WH), body mass index-for-age (BMI), mid-upper arm circumference-for-age (MUAC) and triceps skinfold thickness-for-age (TST) to identify underweight and overweight children and adolescents. METHODS Two data sets were used in this research.(More)
Limited studies have examined the effect of differential item functioning (DIF) on comparing health related quality of life (HRQoL) scores across child self-reports and parent proxy-reports. This study aims to determine whether parents and children respond differently to the items in the Persian version of the PedsQoLTM 4.0 measure. The PedsQLTM 4.0 Generic(More)
Treatment process models are efficient tools to assure proper operation and better control of wastewater treatment systems. The current research was an effort to evaluate performance of a submerged membrane bioreactor (SMBR) treating combined municipal and industrial wastewater and to simulate effluent quality parameters of the SMBR using a radial basis(More)