Functional Ambulation Categories (FAC)

Overview


We conducted a literature search to identify all relevant publications on the psychometric properties of the FAC in individuals with stroke. We identified four studies. More studies are required before definitive conclusions can be drawn regarding the reliability, validity and responsiveness of the FAC.

Floor/Ceiling Effects

No studies have reported on the floor/ceiling effects of the FAC with patients with stroke. However given that it measures the full range of functional walking floor/ceiling effects are not expected.

Reliability

Internal Consistency:
No studies have reported on the internal consistency of the FAC with patients with stroke.

Intra-rater:
No studies have reported on the intra-rater reliability of the FAC in patients with stroke.

Inter-rater:
Collen, Wade and Bradshaw (1990) investigated the inter-rater reliability of the FAC in 25 patients with chronic stroke (2 to 6 years of stroke with residual impaired mobility). Inter-rater reliability between examiners, as measured using kappa statistics was found to be be poor (k=0.36).

Mehrholz et al. (2007) examined the inter-rater reliability of the FAC in 55 clients with subacute stroke admitted to a rehabilitation hospital. Clients were within 2-months post stroke. Inter-rater reliability was found to be excellent (k.905). Researchers believe that the use of key questions, video recordings and experienced examiners improved the inter-rater reliability in this study.

Test-retest:
Mehrholz et al. (2007) examined the test-retest reliability (one week apart) of the FAC by administering the measure to a sample of 55 clients with stroke (< 60 days since onset). The correlation between the two evaluations was excellent (k=.950), indicating that the FAC has excellent test-retest reliability.

Validity

Content:
No studies have reported on the content validity of the FAC with patients with stroke.

Criterion:
No studies have reported on the criterion validity of the FAC with patients with stroke.

Concurrent:
Mehrholz et al. (2007) examined the concurrent validity of the FAC and commonly used measures of gait performance, the Rivermead Mobility Index (RMI), 6 Minute Walk Test (6MWT), walking velocity and stride length in 55 patients with stroke. Evaluations were performed at admission, 2 and 4 weeks, and 6 months. Concurrent validity was measured using Spearman correlations. Correlations between the FAC and RMI, 6MWT, walking velocity and stride length from baseline to 6-months were excellent (k=.841; k=.795; k=767; k=.805 respectively).

Predictive:
Mehrholz et al. (2007) examined whether FAC scores assessed following a 4-week rehabilitation program could predict functional community ambulation at 6-month follow-up in 55 patients with subacute stroke. Community ambulation was defined as the ability to walk faster than 73m/min, longer than 332m, climb stairs and curbs; patients that met all three community ambulation criteria were deemed community ambulators. Predictive validity, as calculated using a Receiver Operating Characteristic (ROC) curve, was highest for ROC cut-off scores ≥ 4 (AUC = 0.89). Thus scoring ≥ 4 on the FAC following a 4-week rehabilitation program is predictive of community ambulation at 6-months.

Sensitivity/Specificity:
No studies have reported on the sensitivity or the specificity of the FAC with patients with stroke.

Construct:
Convergent/Discriminant:
No studies have reported on the convergent/discriminant validity of the FAC with patients with stroke.

Known Groups:
No studies have reported on the known groups validity of the FAC with patients with stroke.

Responsiveness

Earlier studies have suggested that the FAC may lack responsiveness, especially when being used to differentiate between groups at lower levels of functioning (Teasdall et al., 2011). However, a recent study reported moderates to larges effect sizes when the FAC was used to evaluate change in ambulation over a period of 6-months (Mehrholz et al., 2007). Future research is required to determine the responsiveness of the FAC in assessing patients at various levels of functioning.

Mehrholz et al. (2007) assessed the responsiveness of the FAC in evaluating recovery of walking ability in 55 patients with stroke who could not walk without assistance prior to initiating inpatient rehabilitation. The mean score at baseline was 0.44 +/- 0.69 and the mean score at discharge was 2.79 +/- 2.12. The responsiveness to change as measured by the standard response mean (SRM) was was moderate to large: FAC scores changed significantly within the first 2 weeks of the study (SRM=1.016) and between week 4 and study end date at 6 months (SRM=.699); and adequately within weeks 2 and 4 (SRM=.842). The results of this study suggest that the FAC can be used to measure change and outcome in gait performance in patients with stroke.

References
  • Brock, J.A., Goldie, P.A. & Greenwood, K.M. (2002). Evaluating the effectiveness of stroke rehabilitation: Choosing a discriminative measure. Archives of Physical Medicine Rehabilitation, 83, 92-99.
  • Collen, F.M., Wade, D.T. & Bradshaw, C.M. (1990). Mobility after stroke: Reliability of measures of impairment and disability. International Disability Studies, 12, 6-9.
  • Cunha, I.T., Lim, P.A., Henson, H., Monga, T., Qureshy, H. & Protas, E.J. (2002). Performance-based gait tests for acute stroke patients. American Journal of Physical Medicine Rehabilitation, 81, 848-856.
  • Hesse, S., Bertelt, C., Schaffrin, A., Malezic, M. & Mauritz, K.H. (1994). Restoration of gait in nonambulatory hemiparetic patients by treadmill training with partial body-weight support. Archives of Physical Medicine Rehabilitation, 75, 1087-1093.
  • Holden, M.K., Gill, K.M., Magliozzi, M.R., Nathan, J. & Piehl-Baker, L. (1984). Clinical gait assessment in the neurologically impaired. Reliability and meaningfulness. Physical Therapy, 64, 35-40.
  • Holden, M.K., Gill, M.K. & Magliozzi, M.R. (1986). Gait and assessment for neurologically impaired patients. Standards for outcome assessment. Physical Therapy, 66, 1530-1539.
  • Lord, S.E., McPherson, K., McNaughton, H.K., Rochester, L., Weatherall, M. (2004). Community ambulation after stroke: How important and obtainable is it and what measures appear predictive? Archives of Physical Medicine Rehabilitation, 85, 234-239.
  • Mehrholz, J., Wagner, K., Rutte, K., Meiner, D. and Pohl, M. (2007). Predictive validity and responsiveness of the Functional Ambulation Category in hemiparetic patients after stroke. Archives of Physical Medicine Rehabilitation, 88, 1314-1319.
  • Schindl, M.R., Forstner, C., Kern, H. & Hesse, S. (2000). Treadmill training with partial body weight support in nonambulatory patients with cerebral palsy. Archives of Physical Medicine Rehabilitation, 81, 301-306.
  • Simondson, J.A., Goldie, P., Greenwood, K.M. (2003). The Mobility Scale for Acute Stroke Patients: Concurrent validity. Clinical Rehabilitation, 17, 558-564.
  • Stevenson, T.J. (1999). Using impairment inventory scores to determine ambulation status in individuals with stroke. Physiotherapy Canada, 51, 168-174.
  • Teasell, R., Foley, N. C., & Salter K. (2011). EBRSR: Evidence-Based Review of Stroke Rehabilitation. 13th ed. London (ON): EBRSR.