the loss of gait ability after stroke becomes a lifetime disability in addition to social 
 activity limitations .
furthermore , the 
 gait assessment must be reliable and valid to assess the gait disorder and treatment effects 
 and establish a future treatment plan .
however , few gait assessment tools have been 
 described to date that can be used to comprehensively assess gait ability2 .
gait assessment tools currently range from 
 those that use biomechanical and kinematic analyses3 to those with a simple clinical design that can be easily and 
 swiftly applied4 . however , skillful 
 clinicians and repeated tests are required to ease the difficulty of this technological 
 application , save time , and collect accurate data2 .
in addition , impractical issues arise from day - to - day clinical 
 applications due to the difficulty obtaining results and interpreting the data1 . timed up - and - go tests and walking velocity tests ( 512 m ) , which are the most common 
 methods used in clinical research , are basic tests that reflect an individual s gait 
 ability5 .
hence , they can be used as 
 assessment standards since they have the advantage of providing diverse therapeutic 
 interventions by grasping the functional gait performance of patients with data that are 
 affordable to obtain and easy to manage and interpret6 .
gait speed can be a useful assessment tool for estimating 
 functional independence and treatment effects .
stroke patients have different gait speeds 
 since they become stressed about their present functional status ( physical and 
 psychological ) , while the assessment distance may also differ ( 512 m)7 , 8 .
moreover , since 
 speed is measured at a certain point in time , its universal application may be limited .
the inter - rater reliability ( icc ) of the mfac in patients with hip fractures is 0.96 , with 
 a construct validity of r=0.81 on the elderly mobility scale ( ems)9 , while the inter - rater reliability for acute stroke patients 
 has a consistency ratio of 93% and a weighted kappa of 0.9710 .
nonetheless , the inter - rater reliability of the mfac for acute 
 stroke patients has not yet been reported , and there is an unclear correlation between gait 
 speed and functional mobility performance .
in addition , the unmodified fac is still being 
 used in korean clinical research , and the clinical application cases of mfac have not yet 
 been reported in this country .
therefore , the present study aimed to investigate the 
 validity of the correlations between inter- and intra - rater reliability ( icc , kappa , 
 standard error of the mean [ sem ] , and minimum detectable change [ mdc ] ) through which the 
 psychological characteristics of the mfac can be reflected as well as the modified rivermead 
 mobility index ( mrmi ) .
the present study was conducted from september 2014 to may 2015 on 76 chronic stroke 
 patients ( diagnosed more than 6 months earlier ) who were hospitalized at hospital m for 
 treatment .
all of the patients understood the purpose of the study and provided written 
 informed consent prior to participating as required by the ethical standards of the 
 declaration of helsinki .
the subjects were selected if they scored more than 23 points on 
 the mini - mental state examination - korean version ( mmse - k ) , which is designed to test 
 cognitive function , and if they did not have neurological problems in the lower limbs 
 ( determined by the ability to safely walk on a flat surface for 10 m , regardless of the use 
 of a cane or other aids ) and orthopedic problems in either leg . based on the aforementioned 
 criteria ,
76 chronic stroke patients were initially selected , but during the course of the 
 study , 6 dropped out and 4 quit the study after hospital discharge or with deteriorating 
 health . ultimately , the data of 66 patients were obtained .
the mfac , using a 7-point likert scale , was used to make distinctions between the patients 
 gait abilities .
the test and re - test reliability of the mfac among stroke patients has been 
 reported , with a consistency ratio of 93% and a weighted kappa coefficient of 0.9710 .
a gait speed test with a distance of 5  m 
 was performed , during which the research subjects psychological burden and stress can be 
 minimized11 .
the test and re - test reliability of this assessment tool is 
 reportedly high with an icc of 0.880.9712 .
the inter - rater reliability of mrmi for stroke patients had an icc of 0.9813 . in this study
, the shapiro - wilk test was performed using spss ( version 18.0 for windows 7 ) 
 to test variable normality , while a frequency analysis was used to analyze the research 
 subjects general characteristics .
the percent of total agreement and the kappa coefficient 
 were calculated to show the consistency ratio of mfac between the raters , while inter- and 
 intra - rater reliability were measured using the intra - class coefficients 
 ( icc2,1 ) . the absolute reliability ( without measurement error )
in addition , the stable / maximum gait speeds regarding the mfac and mrmi 
 performance scores were compared using the mann - whitney u test and the post - hoc 
 kruskal - wallis test .
the validity testing of the mfac was done with a univariate linear 
 regression analysis , which analyzes the causal relationship between the spearman correlation 
 coefficient and the stable / maximum gait speed regarding functional gait ability and mrmi . 

the research subjects were 38 males ( 57.6% ) and 28 females ( 42.4% ) with an average age of 
 59.82  years . among these subjects ,
42 had cerebral infarction ( 63.6% ) and 24 had cerebral 
 hemorrhage ( 36.4% ) , while 29 had right - sided paralysis ( 43.9% ) and 37 had left - sided 
 paralysis ( 56.1% ) .
the average duration of illness was 13.27 months since onset , and the 
 patients had an average mmse - k score of 25.82 points .
twenty - four patients were able to walk 
 independently ( 36.4% ) , while 25 walked with one - legged walking sticks ( 37.9% ) , 15 walked 
 with 4-legged walking sticks ( 22.7% ) , and 2 patients used walkers ( 3.0% ) .
the average mfac 
 was 5.39 points , and the stable and maximum gait speeds were 60 m / s and 73 m / s , 
 respectively .
the inter - rater reliability of mfac had an icc of 0.982 ( 0.9710.989 ) , kappa coefficient of 
 0.923 , consistency ratio of 94% , sem of 0.174 , and mdc of 0.482 , while the intra - rater 
 reliability had an icc of 0.991 ( 0.9860.995 ) , kappa coefficient of 0.961 , consistency ratio 
 of 96% , sem of 0.124 , and mdc of 0.343 , indicating high reliability .
there was a statistically significant difference between the mfac and the stable / maximum 
 gait speeds ( x=54.49 and 54.70 , respectively ; p<0.001 ) , and a significant 
 difference from mrmi was found ( x=53.76 ; p<0.001 ) .
in addition , mfac validity 
 had high correlations with the stable / maximum gait speeds ( r=0.880.90 ) and mrmi 
 ( r=0.90 ) .
the mfac affected 81% and 77% of the stable and maximum gait speeds , respectively , while 
 affecting 82% of the mrmi .
the present study s findings corroborate the high inter- and intra - rater reliability of the 
 mfac .
such findings are in line with those of previous studies in which the inter - rater 
 reliability of mfac of patients with hip fractures had an icc of 0.969 , while the inter - rater reliability of the mfac for acute 
 stroke patients had a consistency ratio of 93% and a weighted kappa coefficient of 0.9710 .
the inter- and intra - rater reliability of 
 the present study was very high , with an icc>0.98 , kappa coefficient > 0.92 , and a 
 consistency ratio > 94% , all of which were measured by therapists who had worked in the 
 field for at least 10  years .
however , for this study , therapists with < 5  years 
 experience in rehabilitation treatment for stroke patients , or even unskilled therapists , 
 would not have had problems performing video observations and individual assessments . 
 moreover , the mfac has clear standards ; however , in this study , not a single subject scored 
 1 or 2 points on the mfac . regarding assessment tools for clinical research , sem and mdc represent absolute 
 reliability to reflect psychological features for assessing treatment effects and 
 determining effect size , and they offer very useful information for clinicians and 
 therapists14 .
the sem and mdc of the 
 mfac , which had not been explored before , were first introduced in the present study . in 
 this study ,
the sem of the mfac was 0.17 , less than 10% of the average mfac score , while the 
 mdc of the mfac was 0.48 , less than 10% of the maximum mfac score , both of which fall within 
 the acceptable range15 .
the mdc 
 represents the smallest expected value of the individual treatment effect and is a very 
 important indicator for clinicians predicting a patient s achievable recovery level after 
 treatment15 . in the present study
, a difference was noted between the stable / maximum gait speed and mrmi 
 with regard to the mfac groups .
the 66 research subjects were divided into five groups based 
 on the mfac ( 37 points ) , and their stable / maximum gait speeds and mrmi were measured .
they 
 were all reported to be different . as the mfac increased from 3 points ( stable / maximum gait 
 speeds of 0.16 m / s and 0.25 m / s , respectively )
to 5 points ( 0.50 m / s and 0.58 m / s , 
 respectively ) , the average gait speed increased with the mrmi performance score , 
 representing functional mobility .
what is unique is that there was a difference even between 
 the stable and maximum gait speeds of 6 points on the mfac ( 0.76 m / s and 0.89 m / s , 
 respectively ) and of 7 points ( 0.88 m / s and 1.12 m / s , respectively ) among the independent 
 ambulatory group . among the gait phase classifications that are most commonly used in clinical research , such 
 as that of perry ,
a gait speed > 0.4 m / s is used for indoor walking , while 0.40.8 m / s is 
 the gait speed of limited outdoor walking and > 0.8 m / s is used for outdoor walking16 .
in addition , the cut - off value of the 
 gait speed for outdoor walking is 0.661.14 m / s17 , 
 18 .
however , the recent definition of 
 outdoor walking includes a cut - off value and distances of > 0.73 m / s and > 332 m , 
 respectively , and includes being able to go up and down stairs and turn corners 
 independently19 , 20 . according to this definition
, the research subjects in the present 
 study were classified into the outdoor walking group , while the subjects whose minimum mfac 
 score was 6 points were expected to be assigned to the outdoor walking if their gait speed 
 was 0.76 m / s .
the improvement in the functional gait performance of these research subjects ( mfac of 37 
 points ) increased along with increased mrmi , which reflected the stable / maximum gait speeds 
 and functional mobility .
in general , healthy people can adjust their gait performance at 
 different gait speeds . however , most patients with neurological diseases respond slowly to 
 their surroundings because of limited outdoor walking and perform physical activities very 
 passively2 . therefore , improvements in 
 the functional gait performance of stroke patients with gait disability are well - reflected 
 in their gait speed and physical activity performance .
the mfac used in the present study can be a gait assessment tool for clinical research 
 since its validity is proven , inter- and intra - rater reliability are high , and it is 
 relevant to gait speed and functional mobility .
in addition , it is a sophisticated method 
 that can reflect the clinical improvement of a patient s gait ability , and it can be easily 
 used to enhance gait speeds and clinical research designs .
however , the present study has 
 limitations ; its findings can not be generalized because the assessments are limited to a 
 certain period in time , while an assessment to estimate the cut - off distance for outdoor 
 walking was not performed .
future studies should include assessments to estimate the 
 cut - offs for mfac , distance , and other factors for outdoor walking .
 [ purpose ] this study aimed to examine the inter- and intra - rater reliability and validity 
 of the modified functional ambulation category ( mfac ) scale . 
 [ subjects and methods ] the 
 participants were 66 stroke patients with hemiparalysis . 
 the inter- and intra - rater 
 validity of the mfac was calculated using the spearman correlation coefficient . 
 a score 
 comparison of the stable or maximum gait speed with regard to mfac and modified rivermead 
 mobility index ( mrmi ) performances was performed as a univariate linear regression 
 analysis to determine how the kruskal - wallis test affects the mrmi and stable / maximum gait 
 speed with regard to mfac . 
 [ results ] the inter - rater reliability of the mfac ( intraclass 
 coefficient [ icc ] ) was 0.982 ( 0.9710.989 ) , with a kappa coefficient of 0.923 and a 
 consistency ratio of 94% . 
 in contrast , the intra - rater reliability of the mfac ( icc ) was 
 0.991 ( 0.9860.995 ) , with a kappa coefficient of 0.961 and a consistency ratio of 96% , 
 showing higher reliability . moreover , there was a significant difference in stable / maximum 
 gait speed between the mfac and the mrmi . 
 [ conclusion ] since the mfac has sufficient 
 inter- and intra - reliability and high validity , it can be used as an assessment tool that 
 reflects the gait performance and mobility of stroke patients . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION