The Reliability and Validity of a Pediatric Back Outcome Measure.

OBJECTIVE: Young athletes not uncommonly complain of back pain. Many patient-reported outcome measures are used to evaluate back pain, but none have been designed specifically to assess young, athletic patients. The Micheli Functional Scale (MFS) was developed to measure impairment due to back pain in this population. This study examined the reliability, validity, and responsiveness of the MFS used in routine clinical assessments.

DESIGN: Retrospective Cohort Study.

SETTING: Pediatric sports medicine specialty clinic.

INTERVENTIONS: Patients presenting with a chief concern of back pain over 1 year (n = 93) were enrolled in the study. Study subjects were administered the MFS and the revised Oswestry Disability Index (ODI) at each visit as part of routine clinical care.

MAIN OUTCOME MEASURES: Reliability of the MFS was assessed by calculating Cronbach alpha (α). Concurrent validity was determined by measuring Spearman coefficient (rs) for the correlations between the MFS and ODI.

RESULTS: Ninety-three patients (50 female, 43 male), mean age 14.1 ± 2.3 years were enrolled and 242 clinic encounters (71 initial/171 follow-up visits) analyzed. The MFS had acceptable item reliability (α = 0.786) and concurrent validity: the MFS and ODI were strongly and positively correlated [rs = 0.824 (P < 0.001)]. The MFS was comparatively more reliable and valid when used in follow-up versus initial visits.

CONCLUSIONS: The MFS is a reliable and valid instrument in assessing young athletes with back pain, although the instrument has different performance characteristics on initial versus follow-up assessments. Further work is needed to refine the MFS to enhance the instrument's reliability, validity, and responsiveness.

CLINICAL RELEVANCE: This study provides further insight into an outcome measure of clinical use in evaluating young athletes with back pain.