Ontario Society of Occupational Therapists (OSOT) Perceptual Evaluation

Overview

The OSOT has not been well studied. To our knowledge, the creators
of the OSOT have personally gathered the majority of psychometric data
that are currently published on the scale. The psychometric properties
of the original version of the OSOT were based on a study by Boys et
al. (1988) of 80 patients with brain damage (experienced a stroke,
tumor, normopressure hydrocephalus, or anoxia), and a group of 70
neurologically intact participants. The psychometric properties of the
revised version of the OSOT were based on a study by Boys et al. in
1991.

Further investigation on the reliability, validity, and sensitivity
of the OSOT is required with larger numbers of subjects. For the
purposes of this review, we conducted a literature search to identify
all relevant publications on the psychometric properties of the
OSOT.

Reliability

Internal consistency.
Original OSOT:
Boys
et al. (1988) examined the internal consistency of the original
OSOT and reported alpha coefficients ranging from poor (Body
Awareness – Parts recognition, alpha = 0.23) to excellent
(Sensory Function – Localization, alpha = 0.95).

Revised OSOT:
Boys et al. (1991) examined the internal
consistency of the revised OSOT and reported that this version of the
OSOT has an excellent internal consistency (Cronbachs alpha =
0.90).

Inter-rater.
Original OSOT:
Boys et al.
(1988) examined the inter-rater reliability of the OSOT by
having both the attending therapist and one of the investigators score
the performance of 46 patients independently, on separate score
sheets. Agreement for this study was very high (93.1%) across items
for all subjects.

Validity

Sensitivity and specificity.
Boys et al. (1988)
reported that the total score of the original version of the OSOT can
differentiate between individuals with neurological impairment from
neurologically normal control participants. At a total score cutoff of
110, the OSOT can differentiate between individuals with functional
impairment and a control group without neurological impairment from
control participants with a specificity of only 40%. At a cutoff of 100, the sensitivity
was 63.7% and the specificity was 100%.

Boys et al. (1991) reported that the total score of the revised
version of the OSOT can also differentiate between individuals with
brain damage from neurologically normal control participants. The
sensitivity was 100% with a cutoff score of 70 and over, and of
58% with a cutoff of 60. The specificity was 40% with a cutoff
score of 70 and under, and 100% with a cutoff of 60.

Construct

Boys et al. (1988) reported that the moderate correlations observed
between scores obtained for each of the 6 domains of the original OSOT
demonstrates that each domain measures different concepts, which
together give a global perceptual deficit score.

Known groups.
Both the original OSOT and the revised
OSOT have been shown to discriminate between patients with acquired
brain injury and healthy controls (Boys et al., 1991; Boys et al.,
1988). When the performance of patients and control participants were
compared in the study by Boys et al. (1988), statistically significant
differences were observed for all tests except for Ideational
Apraxia.

Concurrent.
Boyd and Dawson (2000) examined the
relationship between perceptual impairment and independence in basic
and instrumental activities of daily living in a sample of
older adults living in an institution or in the community. In this
study, the OSOT correlated adequately with the Physical
Self-Maintenance Scale (PSMS) (Lawton, & Brody, 1969) (r = 0.44),
the Instrumental Activities of Daily Living Scale (r = 0.44), and with
the Mini-Mental State Evaluation (MMSE) (Folstein, Folstein,
& McHugh, 1975) (r = 0.43). The results of this study suggest that
perceptual impairment is related to activities of daily living
status.

References
  • Boyd, A., Dawson, D. R. (2000). The relationship between
    perceptual impairment and self-care status in a sample of elderly
    persons. Physical & Occupational Therapy in Geriatrics,
    17(4), 1-16.
  • Boys, M., Fisher, P., & Holzberg, C. (1991). The OSOT
    Perceptual Evaluation Manual: Revised.
    Scarborough, Ont.: Nelson
    Canada.
  • Boys, M., Fisher, P., Holzberg, C., & Reid, D. (1988). The
    OSOT Perceptual Evaluation: A research perspective. American
    Journal of Occupational Therapy.
    42, 92-98.
  • Desrosiers, J.,Mercier, L.,Rochette, A. (1999).Test-retest and
    inter-rater reliability of the French version of the Ontario Society
    of Occupational Therapy (OSOT)Perceptual Evaluation. Can J Occup
    Therapy,
    66(3), 134 -139.
  • Folstein, M., Folstein, S., McHugh, P. (1975). Mini-mental
    State: A practical method for grading the cognitive state of
    patients for the clinician. Journal of Psychiatric Research,
    12,189-198.
  • Lawton, M. P., Brody, E. M. (1969). Assessment of older
    people: self-maintaining and instrumental activities of daily
    living. Gerontologist, 9, 179-186.
  • Temblay, L. E., Savard, J., Casimiro, L., Tremblay, M. (2004).
    Répertoire des Outils d’Évaluation en Français pour la
    Réadaptation
    (pp406-408). Ottawa, ON: Regroupement des
    intervenantes et intervenants francophones en santé et en services
    sociaux de l’Ontario: Université d’Ottawa: CFORP.