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Rehab Measures: Clinical Outcome Variables Scale

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Available for purchase at the publishers website (external link) 

Title of Assessment

Clinical Outcome Variables Scale 

Acronym

COVS

Instrument Reviewer(s)

Summary Date

 

Purpose

Assesses functional mobility

Description

  • 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

Area of Assessment

Functional Mobility 

Body Part

Not Applicable 

ICF Domain

Activity 

Domain

Motor 

Assessment Type

Observer 

Length of Test

06 to 30 Minutes 

Time to Administer

15-45 minutes

Number of Items

13 

Equipment Required

  • A stopwatch
  • A plastic hospital mug
  • A penny and piggy bank or slotted can
  • An exercise mat
  • A ramp (1 inch to 12 inch rise)
  • A 6-inch platform

Training Required

None necessary

Type of training required

Reading an Article/Manual 

Cost

Not Free 

Actual Cost

  • COVS 2000 packages: $85.00
  • COVS Guidelines Booklet: $30.00

Age Range

Adult: 18-64 years 

Administration Mode

Computer 

Diagnosis

Acquired Brain Injury; Multiple Sclerosis; Stroke; Traumatic Brain Injury 

Populations Tested

  • Stroke
  • Traumatic Brain Injury
  • Multiple Sclerosis
  • Brain Tumor

Standard Error of Measurement (SEM)

Not Established

Minimal Detectable Change (MDC)

Not Established

Minimally Clinically Important Difference (MCID)

Not Established

Cut-Off Scores

Not Established

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

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)

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

Internal Consistency

Mobility Dysfunction: (Seaby, 1989)
  • Excellent Internal Consistency, alpha = 0.93

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 (Convergent/Discriminant)

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)

Content Validity

Not Established

Face Validity

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

Floor/Ceiling Effects

Not Established

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

Professional Association Recommendations

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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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.

Year published

1995 

Instrument in PDF Format

Yes 
Approval Status Approved 
 
Attachments
Created at 10/30/2010 11:36 AM  by Dawood Ali 
Last modified at 12/4/2013 5:59 PM  by Jason Raad