Introduction
Cerebral palsy refers to a group of posture and movement disorders that cause movement restriction and is due to a non-progressive disease in the developing brain [1]. According to the international classification of functioning of disability and health, 4 tools have been developed to classify, describe, and assess how a child performs daily activities, such as walking, manipulating objects, and everyday communication [2]: gross motor function classification system (GMFCS), manual ability classification function (MACS), communication function classification system (CFCS), and eating and drinking ability classification system (EDACS) [3, 4].
To classify the various functions of children with cerebral palsy in a simple and inexpensive way, these four systems are usually used in rehabilitation, medicine, research, and clinical setting with these children [5]. In addition, these classification systems have been translated into more than 15 languages. Studies in different languages have assessed their validities, reliabilities, and other properties [6, 7].
Akmer et al. reported a strong correlation between GMFCS with MACS and also between MACS and CFCS, especially in quadriplegic children. The levels of GMFCS and CFCS had a moderate correlation [5]. While Killian et al. did not find a significant correlation between the GMFCS and the CFCS [8]. Montero-Mendoza and Callo-Munoz reported the high correlation of these four performance classification systems in 52 children with cerebral palsy aged 3-18 in Spain [9]. In previous studies, as mentioned, different correlations have been reported.
No study has been investigated cerebral palsy children’s performance using these four classification systems in Iran. Mobility, object manipulation, eating and drinking, and communication are not functionally related activities. Still, the severity and location of early brain damage may overlap the neural systems used in these activities. This condition can lead to some correlations between classifications. Understanding the relationships between these systems may be important in developing functional profiles for children with cerebral palsy. The present study aims to investigate the relationship between these classification systems in children with cerebral palsy in Iran.

Materials and Methods
This cross-sectional study is of analytical descriptive type. According to the research criteria, the participants were selected from available children with cerebral palsy aged 1-12 years who were referred to public and private clinics and rehabilitation centers in Tehran and Arak cities, Iran, in 2018. The inclusion criteria were as follows: diagnosis of cerebral palsy recorded in the file and age range of 1-12 years. The exclusion criteria included not having a definite diagnosis of cerebral palsy and aged over 12 years. Due to the limited population, all children with cerebral palsy available to the researcher (at least 100) were considered the study sample [10-12]. 
After obtaining written consent from the main caregiver and completing the demographic information questionnaire child’s main caregiver, the classification systems were provided to the child with the cerebral palsy therapist to meet the classification of the child’s performance. The University of Social Welfare and Rehabilitation Sciences Ethics Committee approved this study (IR.USWR.REC.1398.110).
Study tools
MACS classifies the child based on his ability to manipulate objects and the degree of need for assistance or adaptations to perform manual tasks in daily life, where “level 1” is the best manual ability and “level 5” is the lack of manual ability. MACS shows the presence of active hand function in the child. This scale was translated and validated by Riahi et al. in 2013 [13]. MACS, short form, classifies how children with cerebral palsy 1-4 years old use their hands to control objects in daily life [12].
EDACS describes the functional ability to eat and drink in children with cerebral palsy from the age of 3 years. EDACS has identified key components of safety (probability of choking or aspiration) and efficiency (time spent relative to peer group and loss of food and fluids from the mouth) associated with limitations in oral skills required for biting, chewing, and swallowing. The level of assistance needed at mealtime is described on a separate scale. The five distinct ability levels include information about the ability to bite, chew, and swallow, the type of food and fluid administered, respiratory changes associated with eating and or drinking, and the potential for choking and aspiration hazards [14]. This system was translated and validated by Riahi et al. in 2016 [6].
GMFCS is an observational standard classification system such that level 1 indicates “maximum independence” and level 5 “minimum independence” in function. This scale is widely used and it was translated and validated in Iran by Dehghan et al. in 2018 [15].
CFCS emphasizes the importance of understanding and receiving what is said, in other words, the ability to express and send a message. It was translated and validated by Soleimani et al. in 2013 [10].
Data analysis experience    
The Spearman correlation analysis was used to check the relationship between systems. A correlation coefficient less than 0.2 was considered weak, between 0.2-0.4 “relatively weak,” 0.4-0.6 “moderate,” 0.6-0.8 “good,” and 0.8-1 “very good.” Children who were not in the age group of the desired classification system were not included in the data analysis; for example, in the case of the classification system of the ability to eat and drink, children under three years old were not included in the data analysis.

Results
In the current study, there were 154 participants (Mean±SD 49.45±32.22 months). Of these, 87(56.5%) were boys, and 67(43.5%) were girls. Information about children’s classes based on performance levels is presented in Table 1. According to the GMFCS, the highest distribution percentage was 31.2% and 26% in levels II and IV, respectively. In other words, more than 57% of children belong to these two levels. According to the MACS, the highest percentages were distributed in levels II, III, and IV at 28.6%, 22.1%, and 20.8%, respectively. In other words, more than 70% of children belong to these three levels. 
According to the classification system, the ability to eat and drink was almost equally distributed in all levels, except for level V with 4.3%, which had the lowest percentage. According to the CFCS, the highest percentage distribution was 23.5% in levels V and IV.




Information related to the distribution of levels based on GMFCS, MACS, EDACS, and CFCS is presented in Table 2. In terms of numbers, the highest number in the MACS belonged to level II. According to the Table 2, most of these children are at level II of the GMFCS. The same is true for level IV children. Information related to the distribution of levels based on the MACS and the CFCS and the EDACS and the distribution of levels based on the EDACS and the CFCS is provided in Table 2.




The relationship between the GMFCS, MACS, CFCS, and EDACS is presented in Table 3. A significant association was observed in all cases when examining the relationship between functional systems (MACS and GMFCS r=0.672; CFCS and GMFCS r=0.581; EDACS and GMFCS r=0.593; CFCS and MACS r=0.555; EDACS and MACS r=0.664; EDACS and CFCS, r=0.547) (P<0.01).



Discussion
In the current study, a good and significant correlation was reported between the classification system of the GMFCS and the MACS in children with cerebral palsy, which was in line with several studies, including the study of Oskoui et al. [16]. In 2007, Carnahan et al. investigated the relationship between GMFCS and MACS in children with cerebral palsy. They found a weak overall correlation between GMFCS and MACS. However, different associations between GMFCS and MACS were found in different diagnostic subgroups [17]. In 2012, Heidecker et al. first compared three measures of performance, i.e. GMFCS, CFCS, and MACS in a population of 222 children with cerebral palsy. They identified a close relationship between GMFCS and MACS levels in children with cerebral palsy, hemiplegia, and quadriplegia. Still, this relationship was stronger in the subgroup of children with quadriplegia, possibly due to more extensive brain damage, which involves the hands, trunk, and legs [18].
In the current study, a moderate and significant relationship between the classification system of the GMFCS and the CFCS of children with cerebral palsy was reported, which was in line with several studies. Also, in the study of Weir et al., the skill reported in the ability to eat in small children with cerebral palsy between the ages of 1 year and 6 months to 3 years had a significant relationship with gross motor performance abilities [19]. Kalis et al. studied 166 children with cerebral palsy, classified at levels V and IV of the GMFCS. They found that children at level V had more severe swallowing disorders and required dietary restrictions, using swallowing strategies, and depended on others for nutrition [20]. Weir et al. also found that children with 3 or 4 limbs affected had a significantly lower ability to consume ground/rough, chunky/bulky foods and any food with any texture than children with 1 or 2 limbs affected. Those with bilateral distribution also show poorer performance in chunky/bulky foods and other foods than those with unilateral distribution [19]. Weir et al. also observed that children at levels V and IV of the GMFCS performed worse compared to children at level I of the GMFCS (mushy, ground/rough, lumpy/bulky), While children in levels II and III had difficulty in consuming chunky/bulky foods compared to those classified in level I [19].
Himmelman et al. investigated the ability to communicate in cerebral palsy and concluded that the CFCS was related to the GMFCS and the MACS and cognitive function [22]. In 2017, Margarita et al. investigated the autocorrelation between the GMFCS and the CFCS in children with cerebral palsy. They concluded that GMFCS and CFCS in all samples had a moderate correlation at all levels [3]. The result of Margareta et al.’s study, i.e. a significant correlation, was contrary to the survey conducted by Killian et al. on 49 children with cerebral palsy who were selected from a special school for children with complex disabilities [8]. Killian et al.’s previous study did not show a significant correlation and the GMFCS. The conflict and inconsistency between the results are probably due to the different conditions of the studies.

Conclusion
In the present study, there is a moderate and significant relationship between the MACS and the EDACS, the MACS and the CFCS, and the CFCS and the EDACS in children with cerebral palsy. In the study of Heidecker et al., a moderate correlation was reported between the MACS and the CFCS [18]. These studies are comparable as children with more limitations in motor performance show more limitations in other performance classification systems [23].

Ethical Considerations

Compliance with ethical guidelines
In conducting the research, ethical considerations were considered in accordance with the Ethics Committee of The University of Social Welfare and Rehabilitation Sciences (Code: IR.USWR.REC.1398.110). After the participant was fully aware of the research process, written consent was obtained from the main caregiver.

Funding
This study was extracted from the research plan approved by the Research Council of The University of Social welfare and Rehabilitation sciences.

Authors' contributions
Research, investigation and field work: Azadeh Riahi; Analysis and draft writing: Zahra Nobakht; Methodology, editing and finalization of the article: Farin Soleimani and Nahid Rahmani; Supervision and financing: Firozeh Sajdi.

Conflict of interest
According to the authors of this article, there is no conflict of interest.
 

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