ABSTRACT
The relationships between the Expanded Hammersmith Functional Motor Scale (HFMSE) and genotype and motor and respiratory outcomes were examined in patients with spinal muscular atrophy types II and III (n = 70). The correlation between the HFMSE and Gross Motor Function Measure was r = 0.98. Correlations between HFMSE and forced vital capacity (percentage of predicted normal) (n = 56) and a functional rating (n = 57) were r = 0.87 and r = 0.92, respectively. Correlations with strength were as follows: knee extension, r = 0.74 (n = 60); elbow flexion, r = 0.77 (n = 61); and knee flexion, r = 0.74 (n = 58). The HFMSE differentiated patients by SMN2 copy number (P = .0007); bi-level positive airway pressure use, <8 versus ≥8 hours/day (P < .0001); ambulatory status (P < .0001); and spinal muscular atrophy type (P < .0001). The HFMSE demonstrates significant associations with established measures of function, strength, and genotype, and discriminates patients based on function, diagnostic category, and bi-level positive airway pressure need. Time of administration averaged 12 minutes. The HFMSE is a valid, time-efficient outcome measure for clinical trials in spinal muscular atrophy types II and III.
Subject(s)
Disability Evaluation , Motor Activity/physiology , Spinal Muscular Atrophies of Childhood/diagnosis , Spinal Muscular Atrophies of Childhood/physiopathology , Aged , Aged, 80 and over , Female , Humans , Knee/physiopathology , Male , Middle Aged , Predictive Value of Tests , Prospective Studies , Reproducibility of Results , Statistics, Nonparametric , Vital Capacity/physiologyABSTRACT
PURPOSE: To develop and evaluate an expanded version of the Hammersmith Functional Motor Scale allowing for evaluation of ambulatory SMA patients. PROCEDURES: Thirty-eight patients with SMA type II or III were evaluated using the Gross Motor Function Measure and the Hammersmith Functional Motor Scale. Based on statistical and clinical criteria, we selected 13 Gross Motor Function Measure items to develop an expanded HFMS. The expanded Hammersmith Functional Motor Scale was validated by comparison with the Gross Motor Function Measure minus the 13 items (GMFM-75) and an assessment of clinical function. The reliability of the expanded Hammersmith Functional Motor Scale in 36 patients was established. FINDINGS: The expanded Hammersmith Functional Motor Scale was highly correlated with the GMFM-75 and the clinical function assessment (p=0.97, and p=0.90). The expanded Hammersmith Functional Motor Scale showed excellent test-retest reliability (International Coordinating Committee = 0.99). CONCLUSIONS: The expanded Hammersmith Functional Motor Scale allows assessment of high functioning SMA type II and III patients. Ease of administration and correlation with established motor function measures justify use in future SMA clinical trials.
