title: The validity and reliability of the functional rating index for evaluating low back pain in athletes. Spinal pain in adolescents: prevalence, incidence, and course: a school-based two-year prospective cohort study in 1,300 Danes aged 11–13
abstract: The purpose of the present study was to determine the reliability and validity of the Functional Rating Index ( FRI ) for athletes with low back pain ( LBP ) . In this cross-sectional and prospect i ve cohort study , the vali date d Persian FRI ( PFRI ) was tested in 100 athletes with LBP and 50 healthy athletes . From the athletes with LBP , data were recollected among 50 athletes with a 7-day interval to examine test-retest reliability . The content validity was excellent , and the athletes with LBP responded to all items with no floor or ceiling effects . The discriminative validity was supported by a statistically significant difference in PFRI total scores between the athletes with LBP and healthy athletes . The concurrent criterion validity was good ( rho = 0.72 ) . The construct , convergent validity was good ( r = 0.83 ) . The internal consistency reliability estimate was high ( Cronbach 's α = 0.90 ) . Factor analysis demonstrated a single-factor structure with an explained variance of 52.22 % . The test-retest reliability was excellent , indicated by an ICC(agreement ) of 0.97 , and the agreement observed in the Bl and and Altman plot demonstrated no systematic bias . It is concluded that the PFRI has excellent psychometric properties for assessing athletes with LBP Background The severity and course of spinal pain is poorly understood in adolescents . The study aim ed to determine the prevalence and two-year incidence , as well as the course , frequency , and intensity of pain in the neck , mid back , and low back ( spinal pain ) . Methods This study was a school-based prospect i ve cohort study . All 5th and 6th grade students ( 11–13 years ) at 14 schools in the Region of Southern Denmark were invited to participate ( N = 1,348 ) . Data were collected in 2010 and again two years later , using an e-survey completed during school time . Results The lifetime prevalence of spinal pain was 86 % and 89 % at baseline and follow-up , respectively . A group of 13.6 % ( 95 % CI : 11.8 , 15.6 ) at baseline and 19.5 % ( 95 % CI : 17.1 , 22.0 ) at follow-up reported that they had pain frequently . The frequency of pain was strongly associated with the intensity of pain , i.e. , the majority of the participants reported their pain as relatively infrequent and of low intensity , whereas the participants with frequent pain also experienced pain of higher intensity . The two-year incidence of spinal pain varied between 40 % and 60 % across the physical locations . Progression of pain from one to more locations and from infrequent to more frequent was common over the two-year period . Conclusions Spinal pain is common at the age of 11–15 years , but some have more pain than others . The pain is likely to progress , i.e. , to more locations , higher frequency , and higher pain intensity over a two-year period
target: Our findings show strong positive evidence for structural validity and internal consistency in patients with SP and LBP .
  The current evidence shows that the FRI is comparable with both the Oswestry Disability Index and the Neck Disability Index in responsiveness .
background: To assess the measurement properties of the Functional Rating Index ( FRI ) and determine whether its measurement properties are comparable with other region-specific question naires .
  In addition to low back pain ( LBP ) and neck pain ( NP ) , multiregion spinal pain ( SP ) is a common problem with a considerable prevalence in the general population .
  The FRI was built to assess physical functioning in patients with SP .
  However , a systematic review assessing evidence of its measurement properties in separated population s and a comparison with other question naires regarding each measurement property is lacking .