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RehabMeasures Instrument

Clinical Outcome Variables Scale

Purpose

The COVS assesses functional mobility across a broad range of neurologic conditions.

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Instrument Details

Acronym COVS

Area of Assessment

Functional Mobility

Assessment Type

Observer

Administration Mode

Computer

Cost

Not Free

Actual Cost

$85.00

Cost Description

COVS 2000 packages: $85.00, COVS Guidlines Booklet: $30.00

Diagnosis/Conditions

  • Brain Injury
  • Stroke Recovery

Key Descriptions

  • Assesses movement from one postural position to another, or from one location to another, within walking or wheeling distance.
  • 10 mobility tasks quantified using a 7-point scale.
  • Scores range from 13 to 91.
  • Higher scores indicate better physical functioning.

Number of Items

13

Equipment Required

  • Stopwatch
  • Plastic Hospital Mug
  • Penny & Piggy Bank (or slotted can)
  • Exercise Mat
  • Ramp (1 inch to 12 inch rise)
  • 6-inch Platform

Time to Administer

45 minutes

15-45 minutes

Required Training

Reading an Article/Manual

Age Ranges

Adults

18 - 64

years

ICF Domain

Activity

Measurement Domain

Motor

Considerations

  • While the COVS remains a widely used instrument, more validation work needs to be completed.
  • Length of administration
  • Requires a number of common objects as part of the measures administration

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Stroke

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Normative Data

Acute Stroke: (Salter et al, 2010; n = 134; (retrospective study) mean age = 68.64 (14.2) years; mean time from stroke to rehab admission 31.84 (59.2) days; average length of stay = 50.36 (29.4) days)

Measure

Mean (SD)

Min / max (%)

COVS Admission

51.90 (18.78)

0.7 / 0.7

COVS Discharge

67.58 (17.5)

0 / 4.5

FIM Admission

73.86 (24.13)

0.7 / 0

FIM Discharge

95.70 24.65)

0 / 1.5

BBS Admission

26.28 17.49)

1.5 / 0.7

BBS Discharge

38.00 16.98)

0.7 / 9.7

SD = Standard Deviation 

COVS = Clinical Outcome Variables Scale
FIM = Functional Independence Measure
BBS = Berg Balance Scale

 

Test/Retest Reliability

 

Criterion Validity (Predictive/Concurrent)

Acute Stroke: (Ekstrand et al, 2008; n = 60; median LOS = 12.0 (2 to 48) days; mean age = 75.9 years)

  • 68.3% (41) discharged to home 
    • Median LOS was for those discharged to home = 8.0 days
  • 31.7% (19) discharged to a rehabilitation clinic or nursing home
    • Median LOS was for those NOT discharged to home = 21 days
  • Each additional point on the admission COVS score decreases the LOS by 2.7%

Construct Validity

Acute Stroke: (Salter et al, 2010)

Correlation matrix for the COVS, BBS and FIM:

 

Admission

Discharge

Admission

 

COVS

BBS

FIM

COVS

BBS

FIM

COVS

1.00

 

 

 

 

 

BBS

0.895

1.00

 

 

 

 

FIM

0.823

0.817

1.00

 

 

 

Discharge

COVS

0.783

0.802

0.737

1.00

   

BBS

0.750

0.818

0.697

0.895

1.00

 

FIM

0.629

0.656

0.796

0.771

0.772

1.00

* All correlations significant at the p < 0.01 level

 

Acute Stroke: (Hajek et al, 1997; n = 66; mean age = 63 years)

 

  • Excellent:  COVS and FIM (r = 0.82)

  • Adequate: COVS and Barthel Index (r = 0.71)

  • Adequate: COVS and Rankin (r = 0.75)

Face Validity

Not statistically assessed, however, items were compiled to be representative of outcomes associated with a typical physiotherapy caseload (Seaby & Torrance, 1989)

Responsiveness

Acute Stroke: (Salter et al, 2010)

SRM's for the*:

  • COVS = 1.23 

  • BBS = 1.16

  • FIM = 1.36


*A value > 0.80 = a large effect size
*A value ~ 0.50 = a moderate effect size 
*A value < 0.20 = a small effect size

Movement and Gait Disorders

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Internal Consistency

Mobility Dysfunction: (Seaby, 1989)

  • Excellent Internal Consistency, alpha = 0.93

Spinal Injuries

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Test/Retest Reliability

Acute Spinal Cord Injury: (Barker et al, 2007; n = 43, (21 (49%) had a complete injury and 22 (51%) an incomplete injury); mean age = 46 (10) years)

Test retest, with one assessment in-person and the other over the phone, mean time between assessments = 4 (4) days 

Correlation between the TCOVS (Telephone administered) and COVS (administered in-person)

  • Excellent for the Composite score (ICC = 0.98)

  • Excellent for the General Mobility subscale (ICC = 0.97)

  • Excellent for the Ambulation Subscale (ICC = 0.99)

Mixed Populations

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Interrater/Intrarater Reliability

Mobility Dysfunction: (Seaby, 1989; n = 102 rehab patients (SCI, Amputee, Neurolocomotor) and 28 physiotherapists)

Excellent interrater reliability, ICC = 0.971 (1 to 2 days between assessments)

Excellent intraater reliability, agreement on all items >85%, items 1, 3, 10 and 11 tended to have lower, but still acceptable, agreement

Bibliography

Barker, R. N., Amsters, D. I., et al. (2007). "Reliability of the Clinical Outcome Variables Scale When Administered Via Telephone to Assess Mobility in People With Spinal Cord Injury." Find it on PubMed

Ekstrand, E., Ringsberg, K. A., et al. (2008). "The physiotherapy clinical outcome variables scale predicts length of hospital stay, discharge destination and future home facility in the acute comprehensive stroke unit." J Rehabil Med 40(7): 524-528. Find it on PubMed

Hajek, V., Gagnon, S., et al. (1997). "Cognitive and functional assessments of stroke patients: an analysis of their relation." Archives of physical medicine and rehabilitation 78(12): 1331-1337. Find it on PubMed

Salter, K., Jutai, J., et al. (2010). "Clinical Outcome Variables Scale: A retrospective validation study in patients after stroke." Find it on PubMed

Seaby, L. and Torrance, G. (1989). "Reliability of a physiotherapy functional assessment used in a rehabilitation setting." Physiother Can 41: 264-271.

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