Research in Developmental Disabilities 36 (2015) 72–77
Contents lists available at ScienceDirect
Research in Developmental Disabilities
Capacity of adolescents with cerebral palsy on paediatric balance scale and Berg balance scale Chanada Jantakat a, Sirinun Ramrit b, Alongkot Emasithi a, Wantana Siritaratiwat c,* a
School of Physical Therapy, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen 40002, Thailand Improvement of Physical Performance and Quality of Life Research Group, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen 40002, Thailand c Research Center in Back, Neck, Other Joint Pain and Human Performance (BNOJPH), Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen 40002, Thailand b
A R T I C L E I N F O
A B S T R A C T
Article history: Received 6 May 2014 Received in revised form 20 September 2014 Accepted 23 September 2014 Available online
The Berg balance scale (BBS) and the paediatric balance scale (PBS) are reliable tools for measuring balance ability. However, reports of BBS and PBS scores in adolescent cerebral palsy have been limited. The objectives of this study were to investigate functional balance capacities, as tested with the BBS and PBS in adolescents with cerebral palsy, to compare the total PBS and BBS scores between Gross Motor Function Classification SystemExpanded and Revised (GMFCS-E&R) levels and to compare the static balance PBS and BBS scores within each GMFCS-E&R level. Fifty-eight school-aged adolescents with cerebral palsy between the ages of 12 and 18 years with GMFCS-E&R levels of I to IV were recruited. The Kruskal–Wallis test was utilized to compare the median scores for the PBS and BBS between the different GMFCS-E&R levels. Wilcoxon signed-rank tests were performed to examine the differences in the static balance scores between the PBS and the BBS within the same GMFCS-E&R levels. The results reveal that there were differences in the BBS and PBS scores among the four GMFCS-E&R levels. A significant difference was found between the BBS and PBS scores only among the patients with cerebral palsy and level III GMFCSE&R. The BBS and PBS are valid and reliable tools for clinical examination and for distinguishing between levels of functional balance in adolescents with cerebral palsy. ß 2014 Elsevier Ltd. All rights reserved.
Keywords: Adolescents with cerebral palsy Berg balance scale Paediatric balance scale
1. Introduction Cerebral palsy (CP) describes a group of neurological disorders of the developing brain that affect the development of movement and posture and cause activity limitations (Rosenbaum, Paneth, Leviton, Goldstein, & Bax, 2007). The motor development of individuals with CP is not age-appropriate compared to typically-developing individuals due to the impaired functional movements of the CP patients (Kerr, McDowell, Parkes, Stevenson, & Cosgrove, 2011; Palisano, Hanna, Rosenbaum, & Tieman, 2009). Several research studies have confirmed that adolescents with CP begin to exhibit declines in gross motor function during puberty or young adulthood (Bar-Haim, Al-Jarrah, Nammourah, & Harries, 2013; Bartlett, Hanna, Avery,
* Corresponding author. Tel.: +66 43 202085; fax: +66 43 202085. E-mail addresses: [email protected] (C. Jantakat), [email protected] (S. Ramrit), [email protected] (A. Emasithi), [email protected] (W. Siritaratiwat). http://dx.doi.org/10.1016/j.ridd.2014.09.016 0891-4222/ß 2014 Elsevier Ltd. All rights reserved.
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73
Stevenson, & Galuppi, 2010; Hanna et al., 2009; Krakovsky, Huth, Lin, & Levin, 2007). Thus, adolescents with CP require more assistance from caregivers beginning at the age of 14 years (Kerr et al., 2011). Hanna and colleagues conducted a 5-year longitudinal cohort study (2009) in which 657 children with CP at ages ranging from 16 months to 21 years had their gross motor functions observed up to 10 times. They found a deterioration of motor function in subjects with GMFCS levels of III, IV and V, and the greatest declines were apparent in subjects with level IV GMFCS. The average losses of 4.7–7.8 points in the GMFM-66 scores were sufficient to produce clinically meaningful changes in the performances of some important gross motor tasks. Evidently, gross motor ability is related to functional balance (Gan, Tung, Tang, & Wang, 2008; Kembhavi, Darrah, MagillEvans, & Loomis, 2002; Kumban, Amatachaya, Emasithi, & Siritaratiwat, 2013); thus poor postural control during the activities of daily living weakens functional mobility, especially in those with moderate and severe CP. Kumban and colleagues (2013) showed that level III GMFCS-E&R children spent more time performing sit-to-stand movements than those with GMFCS levels I and II did (Kumban, Amatachaya, Emasithi, & Siritaratiwat, 2013). Slow movements were used to compensate for poor functional balance. Moreover, the mechanical efficiency of functional activity is significantly lower and highly correlated with balance among subjects with low Berg balance scale (BBS) scores (Bar-Haim et al., 2013). Pavao and colleagues positively encouraged postural control assessment during functional tasks in children with CP to help them understand balance adjustments in their daily lives (Pavao, Santos, Woollacott, & Rocha, 2013). The BBS and the paediatric balance scale (PBS) are 2 functional balance tests which have been recommended as possible functional balance tests for this group of subjects (Kumban, Amatachaya, Emasithi, & Siritaratiwat, 2013a; Pavao et al., 2013). The BBS examines both static and dynamic balance during functional movements. Only a few studies have reported BBS scores for children with CP (Gan et al., 2008; Kembhavi et al., 2002; Kumban, Amatachaya, Emasithi, & Siritaratiwat, 2013). PBS is a modified version of BBS to make it suitable for young children. A recent study has reported that the PBS is capable of discriminating functional balance differences between children aged 4–10 years with GMFCS levels of I to III (Yi, Hwang, Kim, & Kwon, 2012). Both the BBS and the PBS have been shown to be reliable tests that correlate with the performance of functional tasks including activities of daily life (Chen et al., 2013; Duarte, Grecco, Franco, Zanon, & Oliveira, 2014; Gan et al., 2008; Yi et al., 2012). Reliability and validity of both tests have been investigated in children below the age of 15 years (Chen et al., 2013; Franjoine, Gunther, & Taylor, 2003; Gan et al., 2008; Yi et al., 2012), and a recent study investigated the use of the PBS in CP patients with GMFCS levels of I–V who were 0–18 years old (Pavao, Barbosa, Sato, & Rocha, 2014). Nevertheless, limited data has been reported regarding the capacities of the use of the BBS and PBS for adolescents with moderate and severe CP between the ages of 15 and 18 years who have tendencies towards declines in function and balance. In the present study, we hypothesized that the static balance items of the PBS would be easier for these subjects than those of the BBS. The PBS is thus thought to be an applicable functional balance test for adolescents with CP, especially those with moderate to severe levels of impairment. Both the BBS and PBS were tested in CP adolescents with GMFCS levels of I to IV in this study. The purposes of this study were primarily to investigate the abilities of the BBS and PBS scores to discriminate between GMFCSE&R levels I to IV and to examine the differences in the static balance item scores between the BBS and PBS within each GMFCS-E&R level. Also we were interested in the reliabilities of the BBS and PBS in adolescents with CP. 2. Methods 2.1. Participants The study was executed in Srisangwan Khon Kaen School in Khon Kaen province. Utilizing convenience sampling, 58 adolescents with CP (32 boys and 26 girls, aged 12–18 years) were recruited. The inclusion criteria were the following: (1) aged between 12 and 18 years, (2) gross motor ability levels of I to IV based on the Gross Motor Function Classification System-Expanded & Revised version (Palisano, Rosenbaum, Bartlett, & Livingston, 2007): Thai version (GMFCS-E&R; Ramrit, Emasithi, Amatachaya, & Siritaratiwat, 2014), (3) adequate range of motion of the hips, knees, and ankle joints and no other complications that would interfere with the procedure of the test, (4) the ability to achieve shoulder flexion of 90 degrees and to reach forward with both arms, and (5) the ability to communicate and follow the instructions of the study. Subjects meeting any of the following criteria were excluded: having an operation or botulinum injection in the previous 6 months, the inability to follow the instructions, or having other neurological disorders. The mean (SD) age of all participants was 15.09 (1.84) years old. The mean (SD) body weight and height were 38.40 (8.65) kilograms and 147.31 (11.53) centimetres, respectively. Table 1 shows the other characteristics of the participants. All parents or guardians agreed to the participation of their child by signing a statement of informed consent. This study was approved by the Khon Kaen University Ethics Committee for Human Research. 2.2. Description of the data collection site The study was conducted from January to February of 2014. The average number of students with CP aged between 6 and 20 years who studied at the school was 80. There were 2 semesters of school time, and each semester continued for 4 months. Most students boarded at the school and received routine physical therapy programmes once or twice per week from a physiotherapist who worked at the school. The physical therapy programmes consisted of stretching, endurance exercises and walking training. The school provides handicapped facilities such as ramps and handrails along the stairs. All students were able to feed themselves and had good head control. Some students travelled using wheelchairs and required someone
C. Jantakat et al. / Research in Developmental Disabilities 36 (2015) 72–77
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Table 1 Characteristics of all participants (n = 58). Characteristic
GMFCS-E&R I (n = 17)
GMFCS-E&R II (n = 12)
GMFCS-E&R III (n = 13)
GMFCS-E&R IV (n = 16)
Total (n = 58)
Gender (M/F, n) Type of CP (n): Athetosis Spastic unilateral Spastic bilateral Ataxia Agea (years) Body weighta (kg) Heighta (cm) Ambulation aids (n) None Walker Crutches 3-point cane Wheel chair
11/6
9/3
6/7
6/10
32/26
2 15 –
3 8 1
1 12 –
15.0 (14.5:17.0) 39.0 (29.4:48.3) 151.0 (124.0:160.5)
15.5 (13.0:17.0) 38.5 (29.9:44.5) 152.5 (138.5:157.8)
14.0 (12.0:16.5) 33.0 (30.3:43.2) 142.0 (136.5:154.0)
– – 16 – 16.0 (14.0:17.0) 39.0 (35.7:46.4) 144.5 (138.5:152.3)
5 16 36 1 15.0 (13.0:17.0) 37.7 (31.9:45.2) 148.0 (140.0:156.3)
17 – – – –
5 4 2 1 –
– 10 2 – 1
– – – – 16
22 14 4 1 17
GMFCS-E&R: Gross Motor Function Classification System Expanded and Revised version. M: male, F: female. a Values of age, body weight and height are presented with median (25%:75% percentile).
to push them. Most of the students were able to walk with or without assistance or to propel their wheelchair at least one kilometre to and from the dormitories and classrooms. Therefore, not all of the children and adolescents in the community are able to attend this special education school. Those classified as GMFCS-E&R level V are not permitted to attend the school. These persons are required to stay with caregivers at home. 2.3. Outcome measures 2.3.1. Berg balance scale (BBS) The BBS was originally developed to evaluate functional balance in elderly. This ordinal scale consists of 14 items related to the functional skills that are relevant to activities of daily living and focuses on performance rather than underlying balance impairments. The time required to administer the BBS is 20 min, and the test uses a minimum of readily available equipment, such as a stopwatch, a step, a ruler and chairs (Berg, Maki, Williams, Holliday, & Wood-Dauphinee, 1992; Cole, Finch, Gowland, & Mayo, 1994). Each item is scored on a 5-point scale from 0 to 4 points. The maximum score is 56 points, and higher scores indicate better functional balance performance. The BBS has excellent test-retest (ICC = 1.00) and interrater reliability (ICC = 0.99) (Gan et al., 2008). 2.3.2. Paediatric balance scale (PBS) Franjoine and colleagues modified the BBS into the PBS to be used as a balance measure for school-age children with mild to moderate motor impairments (Franjoine et al., 2003). The adaptations were: test sequence, time for maintaining static posture and the test instructions. The equipment was changed to suit the capacities of the children. This test can be administered and scored within 15 min using equipment that is commonly found in schools and clinics. The maximum score is 56 points, and the scoring system is similar to that of the BBS. The PBS has good test-retest (ICC = 0.998) and inter-rater reliability (ICC = 0.997) in children with CP aged 5–15 years (Franjoine et al., 2003), and excellent test–retest (ICC = 0.923) and inter-rater reliability (ICC = 0.972) in young typically-developing children (Franjoine, Darr, Held, Katt, & Young, 2010). 2.4. Procedures The BBS and the PBS were administered for all 58 subjects with CP on the same day by physical therapists with 2 years of clinical experience in paediatric physical therapy. To examine the test-retest and inter-rater reliabilities of the BBS and PBS, two paediatric physical therapists performed each test and individually scored 20 participants twice at an interval of 7 days. Both raters were trained in the administration of the tests and had opportunities to practice with the BBS and PBS prior to data collection. 2.5. Statistical analyses The abilities of the PBS and BBS scores to discriminate between levels I–IV of the GMFCS-E&R were analyzed using the Kruskal–Wallis test because of the non-normal distributions of the outcome measures. Tukey’s tests with ranks were used as a post hoc test to clarify the significant differences between the individual levels. The scores for the static balance items (i.e., standing unsupported, sitting unsupported, standing with eyes closed, standing with feet together, standing with one foot in front and standing on one foot) were analyzed between the BBS and PBS at the same levels of the GMFCS-E&R using the Wilcoxon signed-rank test. A p-value
Contents lists available at ScienceDirect
Research in Developmental Disabilities
Capacity of adolescents with cerebral palsy on paediatric balance scale and Berg balance scale Chanada Jantakat a, Sirinun Ramrit b, Alongkot Emasithi a, Wantana Siritaratiwat c,* a
School of Physical Therapy, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen 40002, Thailand Improvement of Physical Performance and Quality of Life Research Group, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen 40002, Thailand c Research Center in Back, Neck, Other Joint Pain and Human Performance (BNOJPH), Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen 40002, Thailand b
A R T I C L E I N F O
A B S T R A C T
Article history: Received 6 May 2014 Received in revised form 20 September 2014 Accepted 23 September 2014 Available online
The Berg balance scale (BBS) and the paediatric balance scale (PBS) are reliable tools for measuring balance ability. However, reports of BBS and PBS scores in adolescent cerebral palsy have been limited. The objectives of this study were to investigate functional balance capacities, as tested with the BBS and PBS in adolescents with cerebral palsy, to compare the total PBS and BBS scores between Gross Motor Function Classification SystemExpanded and Revised (GMFCS-E&R) levels and to compare the static balance PBS and BBS scores within each GMFCS-E&R level. Fifty-eight school-aged adolescents with cerebral palsy between the ages of 12 and 18 years with GMFCS-E&R levels of I to IV were recruited. The Kruskal–Wallis test was utilized to compare the median scores for the PBS and BBS between the different GMFCS-E&R levels. Wilcoxon signed-rank tests were performed to examine the differences in the static balance scores between the PBS and the BBS within the same GMFCS-E&R levels. The results reveal that there were differences in the BBS and PBS scores among the four GMFCS-E&R levels. A significant difference was found between the BBS and PBS scores only among the patients with cerebral palsy and level III GMFCSE&R. The BBS and PBS are valid and reliable tools for clinical examination and for distinguishing between levels of functional balance in adolescents with cerebral palsy. ß 2014 Elsevier Ltd. All rights reserved.
Keywords: Adolescents with cerebral palsy Berg balance scale Paediatric balance scale
1. Introduction Cerebral palsy (CP) describes a group of neurological disorders of the developing brain that affect the development of movement and posture and cause activity limitations (Rosenbaum, Paneth, Leviton, Goldstein, & Bax, 2007). The motor development of individuals with CP is not age-appropriate compared to typically-developing individuals due to the impaired functional movements of the CP patients (Kerr, McDowell, Parkes, Stevenson, & Cosgrove, 2011; Palisano, Hanna, Rosenbaum, & Tieman, 2009). Several research studies have confirmed that adolescents with CP begin to exhibit declines in gross motor function during puberty or young adulthood (Bar-Haim, Al-Jarrah, Nammourah, & Harries, 2013; Bartlett, Hanna, Avery,
* Corresponding author. Tel.: +66 43 202085; fax: +66 43 202085. E-mail addresses: [email protected] (C. Jantakat), [email protected] (S. Ramrit), [email protected] (A. Emasithi), [email protected] (W. Siritaratiwat). http://dx.doi.org/10.1016/j.ridd.2014.09.016 0891-4222/ß 2014 Elsevier Ltd. All rights reserved.
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73
Stevenson, & Galuppi, 2010; Hanna et al., 2009; Krakovsky, Huth, Lin, & Levin, 2007). Thus, adolescents with CP require more assistance from caregivers beginning at the age of 14 years (Kerr et al., 2011). Hanna and colleagues conducted a 5-year longitudinal cohort study (2009) in which 657 children with CP at ages ranging from 16 months to 21 years had their gross motor functions observed up to 10 times. They found a deterioration of motor function in subjects with GMFCS levels of III, IV and V, and the greatest declines were apparent in subjects with level IV GMFCS. The average losses of 4.7–7.8 points in the GMFM-66 scores were sufficient to produce clinically meaningful changes in the performances of some important gross motor tasks. Evidently, gross motor ability is related to functional balance (Gan, Tung, Tang, & Wang, 2008; Kembhavi, Darrah, MagillEvans, & Loomis, 2002; Kumban, Amatachaya, Emasithi, & Siritaratiwat, 2013); thus poor postural control during the activities of daily living weakens functional mobility, especially in those with moderate and severe CP. Kumban and colleagues (2013) showed that level III GMFCS-E&R children spent more time performing sit-to-stand movements than those with GMFCS levels I and II did (Kumban, Amatachaya, Emasithi, & Siritaratiwat, 2013). Slow movements were used to compensate for poor functional balance. Moreover, the mechanical efficiency of functional activity is significantly lower and highly correlated with balance among subjects with low Berg balance scale (BBS) scores (Bar-Haim et al., 2013). Pavao and colleagues positively encouraged postural control assessment during functional tasks in children with CP to help them understand balance adjustments in their daily lives (Pavao, Santos, Woollacott, & Rocha, 2013). The BBS and the paediatric balance scale (PBS) are 2 functional balance tests which have been recommended as possible functional balance tests for this group of subjects (Kumban, Amatachaya, Emasithi, & Siritaratiwat, 2013a; Pavao et al., 2013). The BBS examines both static and dynamic balance during functional movements. Only a few studies have reported BBS scores for children with CP (Gan et al., 2008; Kembhavi et al., 2002; Kumban, Amatachaya, Emasithi, & Siritaratiwat, 2013). PBS is a modified version of BBS to make it suitable for young children. A recent study has reported that the PBS is capable of discriminating functional balance differences between children aged 4–10 years with GMFCS levels of I to III (Yi, Hwang, Kim, & Kwon, 2012). Both the BBS and the PBS have been shown to be reliable tests that correlate with the performance of functional tasks including activities of daily life (Chen et al., 2013; Duarte, Grecco, Franco, Zanon, & Oliveira, 2014; Gan et al., 2008; Yi et al., 2012). Reliability and validity of both tests have been investigated in children below the age of 15 years (Chen et al., 2013; Franjoine, Gunther, & Taylor, 2003; Gan et al., 2008; Yi et al., 2012), and a recent study investigated the use of the PBS in CP patients with GMFCS levels of I–V who were 0–18 years old (Pavao, Barbosa, Sato, & Rocha, 2014). Nevertheless, limited data has been reported regarding the capacities of the use of the BBS and PBS for adolescents with moderate and severe CP between the ages of 15 and 18 years who have tendencies towards declines in function and balance. In the present study, we hypothesized that the static balance items of the PBS would be easier for these subjects than those of the BBS. The PBS is thus thought to be an applicable functional balance test for adolescents with CP, especially those with moderate to severe levels of impairment. Both the BBS and PBS were tested in CP adolescents with GMFCS levels of I to IV in this study. The purposes of this study were primarily to investigate the abilities of the BBS and PBS scores to discriminate between GMFCSE&R levels I to IV and to examine the differences in the static balance item scores between the BBS and PBS within each GMFCS-E&R level. Also we were interested in the reliabilities of the BBS and PBS in adolescents with CP. 2. Methods 2.1. Participants The study was executed in Srisangwan Khon Kaen School in Khon Kaen province. Utilizing convenience sampling, 58 adolescents with CP (32 boys and 26 girls, aged 12–18 years) were recruited. The inclusion criteria were the following: (1) aged between 12 and 18 years, (2) gross motor ability levels of I to IV based on the Gross Motor Function Classification System-Expanded & Revised version (Palisano, Rosenbaum, Bartlett, & Livingston, 2007): Thai version (GMFCS-E&R; Ramrit, Emasithi, Amatachaya, & Siritaratiwat, 2014), (3) adequate range of motion of the hips, knees, and ankle joints and no other complications that would interfere with the procedure of the test, (4) the ability to achieve shoulder flexion of 90 degrees and to reach forward with both arms, and (5) the ability to communicate and follow the instructions of the study. Subjects meeting any of the following criteria were excluded: having an operation or botulinum injection in the previous 6 months, the inability to follow the instructions, or having other neurological disorders. The mean (SD) age of all participants was 15.09 (1.84) years old. The mean (SD) body weight and height were 38.40 (8.65) kilograms and 147.31 (11.53) centimetres, respectively. Table 1 shows the other characteristics of the participants. All parents or guardians agreed to the participation of their child by signing a statement of informed consent. This study was approved by the Khon Kaen University Ethics Committee for Human Research. 2.2. Description of the data collection site The study was conducted from January to February of 2014. The average number of students with CP aged between 6 and 20 years who studied at the school was 80. There were 2 semesters of school time, and each semester continued for 4 months. Most students boarded at the school and received routine physical therapy programmes once or twice per week from a physiotherapist who worked at the school. The physical therapy programmes consisted of stretching, endurance exercises and walking training. The school provides handicapped facilities such as ramps and handrails along the stairs. All students were able to feed themselves and had good head control. Some students travelled using wheelchairs and required someone
C. Jantakat et al. / Research in Developmental Disabilities 36 (2015) 72–77
74
Table 1 Characteristics of all participants (n = 58). Characteristic
GMFCS-E&R I (n = 17)
GMFCS-E&R II (n = 12)
GMFCS-E&R III (n = 13)
GMFCS-E&R IV (n = 16)
Total (n = 58)
Gender (M/F, n) Type of CP (n): Athetosis Spastic unilateral Spastic bilateral Ataxia Agea (years) Body weighta (kg) Heighta (cm) Ambulation aids (n) None Walker Crutches 3-point cane Wheel chair
11/6
9/3
6/7
6/10
32/26
2 15 –
3 8 1
1 12 –
15.0 (14.5:17.0) 39.0 (29.4:48.3) 151.0 (124.0:160.5)
15.5 (13.0:17.0) 38.5 (29.9:44.5) 152.5 (138.5:157.8)
14.0 (12.0:16.5) 33.0 (30.3:43.2) 142.0 (136.5:154.0)
– – 16 – 16.0 (14.0:17.0) 39.0 (35.7:46.4) 144.5 (138.5:152.3)
5 16 36 1 15.0 (13.0:17.0) 37.7 (31.9:45.2) 148.0 (140.0:156.3)
17 – – – –
5 4 2 1 –
– 10 2 – 1
– – – – 16
22 14 4 1 17
GMFCS-E&R: Gross Motor Function Classification System Expanded and Revised version. M: male, F: female. a Values of age, body weight and height are presented with median (25%:75% percentile).
to push them. Most of the students were able to walk with or without assistance or to propel their wheelchair at least one kilometre to and from the dormitories and classrooms. Therefore, not all of the children and adolescents in the community are able to attend this special education school. Those classified as GMFCS-E&R level V are not permitted to attend the school. These persons are required to stay with caregivers at home. 2.3. Outcome measures 2.3.1. Berg balance scale (BBS) The BBS was originally developed to evaluate functional balance in elderly. This ordinal scale consists of 14 items related to the functional skills that are relevant to activities of daily living and focuses on performance rather than underlying balance impairments. The time required to administer the BBS is 20 min, and the test uses a minimum of readily available equipment, such as a stopwatch, a step, a ruler and chairs (Berg, Maki, Williams, Holliday, & Wood-Dauphinee, 1992; Cole, Finch, Gowland, & Mayo, 1994). Each item is scored on a 5-point scale from 0 to 4 points. The maximum score is 56 points, and higher scores indicate better functional balance performance. The BBS has excellent test-retest (ICC = 1.00) and interrater reliability (ICC = 0.99) (Gan et al., 2008). 2.3.2. Paediatric balance scale (PBS) Franjoine and colleagues modified the BBS into the PBS to be used as a balance measure for school-age children with mild to moderate motor impairments (Franjoine et al., 2003). The adaptations were: test sequence, time for maintaining static posture and the test instructions. The equipment was changed to suit the capacities of the children. This test can be administered and scored within 15 min using equipment that is commonly found in schools and clinics. The maximum score is 56 points, and the scoring system is similar to that of the BBS. The PBS has good test-retest (ICC = 0.998) and inter-rater reliability (ICC = 0.997) in children with CP aged 5–15 years (Franjoine et al., 2003), and excellent test–retest (ICC = 0.923) and inter-rater reliability (ICC = 0.972) in young typically-developing children (Franjoine, Darr, Held, Katt, & Young, 2010). 2.4. Procedures The BBS and the PBS were administered for all 58 subjects with CP on the same day by physical therapists with 2 years of clinical experience in paediatric physical therapy. To examine the test-retest and inter-rater reliabilities of the BBS and PBS, two paediatric physical therapists performed each test and individually scored 20 participants twice at an interval of 7 days. Both raters were trained in the administration of the tests and had opportunities to practice with the BBS and PBS prior to data collection. 2.5. Statistical analyses The abilities of the PBS and BBS scores to discriminate between levels I–IV of the GMFCS-E&R were analyzed using the Kruskal–Wallis test because of the non-normal distributions of the outcome measures. Tukey’s tests with ranks were used as a post hoc test to clarify the significant differences between the individual levels. The scores for the static balance items (i.e., standing unsupported, sitting unsupported, standing with eyes closed, standing with feet together, standing with one foot in front and standing on one foot) were analyzed between the BBS and PBS at the same levels of the GMFCS-E&R using the Wilcoxon signed-rank test. A p-value
