Impairment, disability and loss of function scales and scores

A variety of injury and health loss scores are used in post impact care. These are used for assessing injury severity, the probability of survival and long term loss of health. They are used in the field for determining the appropriate hospital for the crash victim, evaluating trauma system performance and for research purposes.

Anatomical scoring systems

The Abbreviated Injury Scale (AIS), first published in 1971 (Committee on Medical Aspects of Automotive Safety 1971), is the most widely used scheme internationally for injury severity assessment. Currently in its sixth revision, the AIS (2005) is a dictionary of approximately 2,000 descriptions of individual injuries, mainly anatomically-based, written in currently acceptable medical terminology. While many of the injury descriptions are clinically-specific and require some knowledge of contemporary trauma language, the AIS is so structured that it can equally accommodate less detailed information, thus fostering compatibility across different data needs and uses. The bedrock of the AIS is its 6-point numerical severity ranking system (AIS 1=minor injury; AIS 6=injury currently untreatable) that has remained virtually unchanged for three decades. By its nature, the AIS can be used by both medical and non-medical researchers [27].The AIS does not reflect the combined effects of multiple injuries but can give some indication of an overall severity score when used as part of ISS.

The Injury Severity Score (ISS) is an anatomical scoring system that provides an overall score for patients with multiple injuries. It is used to assess penetrating injuries, falls, crush-type injuries as well as road traffic accident injuries. AIS is the basis for the Injury Severity Score (ISS). Its limitations are its inability to account for multiple injuries to the same body region and it limits the total number of contributing injuries to only 3. However, the NISS (new injury severity score) accounts for multiple injuries in the same body region.

International Classification of Disease, Tenth edition (ICD 10)The ICD has become the international standard diagnostic classification for all general epidemiological and many health management purposes. Compared to AIS, its limitation is the absence of severity score.

Physiological response scales and scores

The Glasgow Coma Scale is used as a standard assessment of levels of consciousness following or when suspecting a head injury - this is used by paramedics and throughout the hospitals and is widely accepted in UK, Europe, U.S, Australia etc.

The Revised Trauma Score is a physiological scoring system, with high inter-rater reliability and demonstrated accuracy in predicting death. It is scored from the first set of data obtained on the patient, and consists of the Glasgow Coma Scale, Systolic Blood Pressure and Respiratory Rate. The revised trauma score is used to rapidly assess patients at the scene of an accident and to facilitate pre-hospital triage decisions and evaluation [10].

Both are used widely although use is limited when a patient is intubated, chemically paralysed or under the influence of alcohol and drugs.

Probability of survival scales and scores

Trauma Score - Injury Severity Score: TRISS This widely used score is designed to determine the probability of survival of a patient based on patient characteristics and was designed to evaluate trauma care and outcomes from different trauma centres [3].

Outcome scores

More recently, the development of an injury outcome scale has become a priority. While the topic is not new - scales date back to the 1980s [24][22][5] - there is still significant disparity on what criteria to use, although there seems to be agreement that any future impairment scale should be directly linked to the AIS.

Injury Impairment Scale (IIS) [1]. It was fashioned directly on the AIS severity code and assigned a value between 1 and 6 to each injury descriptor that was adjudged to have some residual impairment one year post injury. Several years later, the Functional Capacity Index (FCI) [30] was proposed.

The Glasgow Outcome Score has also been used which a crude 5 point scale of functioning is made at the time of hospital discharge.

The Functional Capacity Index (FCI) was developed through a large collaborative effort in the US [30]. It assigns a score (between 0 and 1) to each injury descriptor in the AIS in all body regions. The FCI, also directly linked to the AIS, has been validated on one patient population in the US and some revisions to the Index were subsequently proposed. It is anticipated that the FCI will be integrated into the AIS dictionary thus offering substantial opportunities to validate it as a research tool to assess the probability and severity of injury-related impairment [27]. Validation for the Functional Capacity Index in Europe may be required [20].

Health loss scales

The EQ-5D scale assesses changes in health states in 5 domains; mobility, self care, usual activity, pain, and anxiety and depression. Each domain has 3 levels of assessment and the scores can be combined to derive a composite outcome measure and used to calculate Quality Years of life lost (Qalys). Population measures are available so that the distributions of an injured sample can be compared [19].

The SF-36v2 assesses health across 8 dimensions namely, general health, physical role and functioning, social functioning, bodily pain, mental health, vitality and emotional role. The assessment incorporates the previous 4 weeks and not just a one off assessment. Scores are generated for each dimension ranging between 0-100 which are then used to generate two component scores, namely the physical component and mental component scores (PCS and MCS respectively). These can be compared with standard values for specific populations to assess trends over time and absolute changes in health [55].