Disability Rating Scale

The Disability Rating Scale (DRS) was developed to provide quantitative information regarding the progress of individuals with severe head injury from “coma to community” (Rappaport et al. 1982). The DRS was designed to reflect changes in the following areas: arousal and awareness, cognitive ability to deal with problems around self-care, degree of physical dependence, and psychosocial adaptability as reflected in the ability to do useful work (Rappaport et al. 1982). The DRS was developed and tested in a rehabilitation setting among individuals who had experienced moderate to severe TBI (Hall 1997).

The DRS is comprised of eight items in four categories: i) level of consciousness; ii) cognitive abilities; iii) dependence on others; and iv) employability (Rappaport et al. 1982). Each item has its own rating scale ranging from 0-3 to 0-5 and are either in ½-point or 1-point increments. Rating forms are available for download at http://tbims.org/combi/drs/drsrat.htm. The total or composite score is calculated by summing the ratings for all 8 items, so that lower scores are associated with less disability. The overall score can be used to assign the individual to one of 10 disability outcome categories ranging from no disability (DRS score=0) to extreme vegetative state (DRS score=29) and death (DRS=30) (Fleming & Maas 1994; Hall et al. 1996).

The DRS is available at no cost and is free to copy. Training materials are also provided on the same website and a training video is available for a modest fee. Administration of the scale may be via direct observation or interview (Hall et al. 1993). When necessary, collateral sources of information may be used to complete the ratings (Rappaport et al. 1982). The DRS is simple to administer and requires approximately 5 minutes to complete (Hall et al. 1993; Hall 1997).

Table: Characteristics of the Disability Rating Scale

Advantages. The DRS is a single assessment comprised of items spanning all major dimensions of impairment, disability and handicap (Hall et al. 1996; Rappaport et al. 1982). It is a brief and simple tool that allows for the ongoing assessment of recovery from injury to community re-integration. In addition, the ability to assign scores to outcome category with relatively little loss of information (Gouvier et al. 1987) provides a quick snapshot of the individual’s overall disability status (Hall et al. 1993). The DRS appears to be more reliable and valid than the Level of Cognitive Functioning Scale (LCFS) and may be more sensitive to change than categorical rankings such as the Glasgow Outcome Scale (GOS) (Hall et al. 1985). In addition, Glasgow Coma scores can be obtained from the DRS (Hall 1997). 

Limitations. Descriptions of what corresponds to successful item performance at each rating level are not precise and subscales do not clearly identify areas for intervention (Brazil 1992). The sequelae of head injury that are included for assessment are limited and do not include formal cognitive assessment (Brazil 1992). The DRS assesses only general rather than specific function or functional change (Hall & Johnston 1994). It may be most useful as a means to characterize sample severity and provide the means for comparison to other groups, but it is not particularly sensitive to the effects of treatments designed to ameliorate specific functional limitations or social participation (Hall et al. 1993). In inpatient rehabilitation settings, the FIM is a more sensitive instrument with which to monitor change (Hall & Johnston 1994).

The DRS is not well suited to patients with mild TBI or very severe impairments (Hall et al. 1993; Hall et al. 1996; Wilson et al. 2000). It has been recommended that ½ point scoring increments rather than whole points should be employed in order to increase the precision and sensitivity of the instrument when assessing higher functioning individuals (Hall et al. 1993). When subjects do not fit whole-point definitions for cognitive ability for self-care items, dependence on others and employability, ½ points can be awarded; total scores with ½ points are rounded down for the purposes of assignment to outcome category (Hammond et al. 2001). The rating form available for download has included the ½ point scoring option. When using the ½ point scoring option, the DRS does appear to be sensitive to change between discharge and one-year and even 5-year follow-ups. However, year-by-year change is not captured by DRS ratings more than one year post-injury (Hammond et al. 2001). 

 

Summary-Disability Rating Scale

Interpretability: The DRS is widely used and is part of the TBI Model Systems Database. It provides a quick, accessible snapshot of outcomes of disability in terms of general function. 

Acceptability: The simplicity and brevity associated with the DRS would suggest little to no patient burden associated with its administration. Ratings provided by family members are strongly correlated with those completed by healthcare team members. 

Feasibility: The DRS is free to use and copy. Training materials are also provided free of charge and a training video is available for a modest fee. The DRS seems to be able to detect significant change over time and may be well suited for group comparisons.

 

Table: Disability Rating Scale Evaluation Summary

Reliability

Validity

Responsiveness

Rigor

Results

Rigor

Results

Rigor

Results

Floor/ceiling

+

 

 

+++(TR)

+++(IO)

++(IC)

+++

+++

++

+ (p-values only)

+ (ceiling)

NOTE: +++=Excellent; ++=Adequate; +=Poor; N/A=insufficient information; TR=Test re-test; IC=Internal Consistency; IO=Interobserver; Varied (re. floor/ceiling effects; mixed results).