Wright, Santa Clara Valley Medical Center at
Citation Wright, J. (2000). The
Disability Rating Scale. The Center for Outcome Measurement
in Brain Injury. http://www.tbims.org/
combi/drs ( accessed
This citation is for the COMBI web material. Mr. Wright is
not the scale author for the DRS.
of the DRS
reliability of the DRS was established among three raters on a sample
of 88 TBI rehabilitation inpatients (Rappaport et al., 1982). Pearson
correlations were .97-.98. In a separate study by Gouvier (1987),
Spearman rho correlation coefficients were .98 among three raters
on a sample of 37-45 subjects.
et al. (1991) reported inter-rater reliability in a study of 27
severely brain injured persons. A comparison of DRS ratings by family
members vs. rehabilitation professionals yielded significant correlations
for both rehabilitation admission (r=.95) and discharge (r=.93)
reliability was demonstrated by Gouvier (1987) in which a Spearman
rho correlation of .95 was reported.
of the DRS
Validity was established in the initial publication on the DRS (Rappaport
et al., 1982), in which abnormality ratings of the auditory, visual
and somatosensory brain evoked potentials were significantly correlated
with DRS ratings (r=.35 to .78). Additional validation of the scale
is documented in a published article by K. Hall and co-workers (1993).
of DRS with simultaneously obtained GOS scores at two time intervals
was demonstrated in a sample of 70 TBI inpatients (r=.50 at admission
and .67 at discharge; Hall et al., 1985). Gouvier found a Spearman
rho correlation of .92 between the rehabilitation admission DRS
and the Stover Zeiger Scale (1976). The rehabilitation discharge
DRS was correlated .81 with the discharge S-Z, .80 with the GOS
(1975, 1981), and .85 with the Expanded GOS (Smith 1979).
scores obtained on 128 individuals within 72 hours of CVA or TBI
were significantly correlated with acute hospital length of stay,
DRS scores at discharge, and disposition at discharge (r=.50, .66
and .40 respectively; Eliason and Topp, 1984). Predictive validity
of the DRS at admission was also demonstrated by Gouvier (1987).
The correlation with the discharge S-Z was .65, and with the Expanded
Glasgow Outcome Scale (Smith and Fields, 1979), r=.73. Initial DRS
scores correlated significantly (r=.53, p<.01, n=77) with DRS
one year later (Rappaport, 1982). Fryer and Haffey (1987) reported
the DRS at admission to a cognitive rehabilitation program as a
strong predictor of disability at follow up (r=.77, p< .001).
It also discriminated between those outpatients who received Cognitive
Rehabilitation/Community Readaptation training vs. those who did
Ability of the DRS to Predict Employment
DRS has been used to predict employment after TBI. Novack et al.
(1988) stated that "the DRS documents recovery from disability and
may help in predicting outcome, particularly for the more severely
injured." His study found that DRS scores >15 on rehabilitation
admission, >7 on discharge, and >4 at three months were incompatible
with return to work one to two years post injury.
a sample of 145 TBI clients, Cope et al. (1991) reported a differential
return to competitive employment or school based on rehabilitation
admission DRS scores. One year post-discharge from a post-acute
rehabilitation system, 62% of those with an admission DRS of 1-3
(mild) were employed competitively or in school. In the group with
an admission score of 4-6 (Moderate), 39% were employed or in school
one year later. Those with a DRS of 7-20 (severe) had an 11% employment/school
rate one year later. That is, only 6 of the 54 clients falling in
the severe range on admission were working competitively or in school
one year later.
a sample of 55 cases of TBI (average DRS of 13.3 (severe) at rehabilitation
admission and 5.7 (moderate) at follow-up, Rappaport et al. (1989)
found that 9% were employed full-time five to ten years after their
injury. Additionally, none of the individuals who previously held
professional positions were able to return to them after the injury,
and none of the other TBI individuals were able to attain professional
positions. Eighty-seven percent of these people were dependent on
society to provide financial support for the basic fundamentals
of food, clothing, and shelter. None of these individuals was dependent
and Kilgore (1990) found that the rehabilitation admission and discharge
DRS scores combined predicted return to work with 76% accuracy in
a sample of 57 individuals with TBI. In a later study, Rao and Kilgore
(1992) found no significant difference between the DRS and other
good predictors of return to work/school. When they considered a
history of substance abuse as a negative indicator, the DRS (admission+discharge
scores) predicted correctly 17 of 19 cases as unable to return to
work 14 to 26 months after injury.
Analysis (Hall et al., 1993)
analysis was completed on the eight DRS item scores at rehabilitation
admission for 266 cases. Composite scores of 1 to 29 were obtained
(0 is normal, 30 is dead: clients who were rated "normal" were omitted).
The findings were:
relative level of difficulty between admission and discharge ratings
of the DRS items for 256 cases was consistent.
range of difficulty reflected in the scale is excellent, from
items measuring very simple functioning to those measuring complex
level of difficulty of the items is as follows: Eye Opening, Communication
Ability, Motor Response, Feeding, Toileting, Grooming, Level of
Functioning, and Employability.
difficulty level of the three items "Cognitive Ability for Feeding,
Toileting, and Grooming" were very similar.
is a "gap" between "Cognitive Ability for Feeding, Toileting and
Grooming" and "Level of Functioning" (i.e. ability to live independently)
and between the latter and "Employability." The functional difficulty
of each of these items is substantially different, with no intervening
items to reflect intermediate abilities. This is consistent with
the observation of less sensitivity to change in the DRS in individuals
at high functional levels.
summary, the Rasch analysis provided transformed scores for use
in interval scale data analyses and validated the observations about
the DRS: a scale that measures a wide range of disability with less
sensitivity at the high end (mild TBI). Items discriminate well
the varying levels of disability and relative difficulty of items
remains constant between admission and discharge.
the analysis of the TBI Model Systems National Database data, the
average DRS untransformed score at rehabilitation admission was
12 (rounded), at discharge, 5, and at one year post injury follow
up, 3, in a sample of 70 cases with complete data at all three time
Effects (Hall et al., 1996)
average DRS scores at rehabilitation admission, discharge, one year
and two years post injury for all cases with data in the TBI Model
Systems database were analyzed for ceiling and floor effects.
is defined as mean score of 0, 1 or 2 on the DRS (top 10% of scale).
These "ceiling" scores define independent or modified independent
status. The DRS has virtually no ceiling effect at discharge, year
1 and year 2 after injury on a consistent sample over time. Results
including all cases with data available at any time period were
similar, with sample sizes ranging from 598 to 206.
DRS was developed with the continuum of recovery in mind. The DRS
consistently demonstrates good scale properties and has been shown
to predict employment well. At one year post injury, twenty-nine
percent of the FIM and FIM+FAM scale reflects independence/modified
independence (scores of 6 and 7 on a 7 point scale) and only 10%
of the DRS summed score represents this level of independence (scores
of 0,1 and 2 on a 30 point scale). This difference gives the DRS
an advantage in regard to ceiling effect.
of .5 ratings:
1994, the Traumatic Brain Injury Model Systems (TBIMS) National
Database adopted a 0.5 rating option for the last 5 items of the
DRS. Although raters found the half point discrimination useful,
no validation study was ever completed on the use of the 0.5 rating
option. In 2010, the TBIMS National Database members voted to omit
the 0.5 rating option. Use of the 0.5 rating option after April
1, 2010 is not recommended.
is no cost for using the DRS and it is free to copy.