Measuring and assessing risk of quality of life loss following a road traffic injury: A proposed methodology for use of a composite score

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Highlights

  • The burden of a road traffic injury was computed using a composite score comprising factors related to long-term quality of life loss.

  • The score included number of injuries, severity, and body parts affected, and it was grouped into five exposure categories of increasing severity.

  • Binary logistic regression was used to investigate whether the exposure categories were predictive of low quality of life (QoL).

  • Low QoL was defined below 90% or 80% of the mean QoL score of a sample frequency-matched by sex and age of non-injured individuals.

  • Compared with non-injured individuals, victims of any injury category had a higher risk of impoverished QoL 1–4 years after the crash.

Abstract

Introduction

Assessments of the impact of road traffic injuries (RTIs) on quality of life (QoL) can benefit from the use of combined characteristics of the injurious event.

Aim

The burden of having sustained a RTI was computed using a composite score that comprised three elements (i.e. number of injuries sustained in the crash, body parts affected, and severity of the injuries) that relate to the probability of subsequent long-term QoL lost by individuals 1–4 years after the crash.

Methodology

The QoL of injured victims aged 11–90 years that crashed in Sweden between 2007 and 2009 was compared with that of a random sample of non-injured individuals frequency-matched by sex and age. Injury information to build the composite score was obtained from a national register that contains data on the number of injuries, their severity, and the body parts affected. The QoL was assessed in 2010 for both injured and non-injured individuals using the standardized Euro Quality of Life questionnaire. Logistic regression was used to investigate whether the composite score was predictive of low QoL (<90% of the mean of non-injured referents) adjusting for sex, age, and time elapsed since the injury occurrence. The composite score was grouped into five exposure categories (0.01–1, 1.01–1.5, 1.51–2, 2.01–3 and 3.01–9 units).

Results

Compared with the non-injured reference group, all exposure categories showed statistically significant increased adjusted ORs for low QoL ranging from 2.35 (95% CI 1.48–3.72) in the 0.01–1.00 lowest injury category to 6.10 (95% CI 3.65–10.2) in the highest 3.01–9.00 with a slightly decreasing plateau in the intermediate categories (point ORs between 3.86 and 3.06). Yet, all 95% CIs across the exposure categories overlapped.

Conclusion

Long-term reduction in QoL is a burden experienced by the victims of mild to severe RTCs. The proposed composite score can be an initial step in the development of more elaborated instruments that can be useful in policy making and regulation.

Introduction

More than one billion people are disabled worldwide; from these, a large proportion is associated with injury events, which are responsible for 11% of all disability-adjusted life years (DALYs) (Lozano et al., 2012; Murray et al., 2013). Many of these injuries are the result of road traffic crashes (RTC). In fact, nearly 50 million people suffer from non-fatal road traffic injuries (RTIs) every year resulting in long-term impairment (WHO, 2013). Victims often do not recover their pre-crash health even after 18 months of the event (Ameratunga et al., 2006).

Quality of life (QoL) among RTI survivors has been a key element of the road traffic burden. Understandably, research within this area has focused mostly on individuals who have sustained severe injuries (Ameratunga et al., 2006; Fitzharris et al., 2007). Even sexual function after traumatic pelvic fracture has been studied and associated with lower QoL among injured individuals one year after the crash (Harvey-Kelly et al., 2014).

Studies on minor or less severe RTIs and QoL are scarcer, but there is indirect evidence pointing to relevant short- and long-term consequences. An Australian study reported that individuals with minor RTIs from an emergency unit had physical and mental baseline QoL scores below the reference norm, which improved slightly at six months, but not thereafter (Littleton et al., 2011). Another study with hospitalized and non-hospitalized injured drivers, as surrogates of injury severity, also reported lower general and mental health in both groups after 5–18 months of the crash compared with baseline measures, indicating that the longer-term health burden would likely be “underappreciated” among those not hospitalized (Ameratunga et al., 2006).

A study aimed at identifying predictors of the evolution of QoL following accidental injuries showed that while reduced occupational function was attributable to injury severity, it did not have a direct effect in the predicted change in subjective QoL (Moergeli et al., 2012). Actually, researchers have noticed that significant improvement in QoL can persist up to the second year, mostly for physical functioning, but not for mental health (Soberg et al., 2007).

Recently, there has been interest about the effect of RTCs in survivors with mild injuries. One study found that individuals with minor injuries had poor physical and mental health-related QoL, especially when high pain levels and comorbid psychiatric disorders are present (Kenardy et al., 2015); such low QoL levels did not improve even after two years of the crash. Another study comparing QoL between whiplash patients and other injuries one year after the crash reported that sociodemographic factors, pre-accident psychological history, and post-traumatic stress disorder had more impact in the QoL than the type of injury sustained (Hours et al., 2014).

Identifying which injuries will lead to future disabilities has been a difficult task due to the limited correlation between the initial assessment and the long-term consequences of the injuries. Measures like the Abbreviated Injury Scale (AIS) (States, 1969), from which other instruments have been derived, including the Injury Severity Score (ISS) (Baker et al., 1974) and the New ISS (Osler et al., 1997), have focused on the survival probability of injured individuals shortly after the crash to predict life-threatening injuries, but not so on their long-term impact. In the early eighties, the Rating System for Serious Consequences was proposed to recognize permanent medical impairments by body regions according to AIS categories (Gustafsson et al., 1985). Attempts have also been made to assign an impairment score to AIS diagnoses based on medical consensus and loss of individuals’ income (Miller, 1993) or on their functional capacity one year after the injury (MacKenzie et al., 1996), and more recently the health-related QoL has been used to measure the change in health status over time (Coons et al., 2000). Yet, efforts to develop an appropriate method are still needed, to which this study could be a contribution, as it proposes the use of a composite measure that includes relevant dimensions of the injury burden in terms of its impact on the future QoL of individuals injured in RTCs.

In this study we computed a relatively simple composite score that takes into account key injury dimensions (i.e. number, location, and severity) to assess the overall burden of injuries in the QoL lost by individuals one to four years after the RTC occurrence. We believe that such measure can give further perspective for the development of a more refined and validated index that can be of use in policy making and regulation by public and private institutions.

Section snippets

Study design

The QoL of injured victims aged 11–90 years that crashed in Sweden between 2007 and 2009 was compared with that of a random sample of non-injured referent individuals using frequency matching by sex and age.

The data for the analyses conducted here were assembled using both primary (i.e. survey) and secondary (i.e. register) sources. The severity of each distinct injury was assessed using the AIS (States, 1969), a validated measure to classify and describe the severity of injuries (AAAM, 2005),

Results

Table 1 presents characteristics of the injured and referent individuals. The proportions of males and females among injured people was similar, but there were slightly more women in the reference group (p = 0.03). The mean age of the injured and comparison group was also very similar (∼46.5 y, p = 0.79), but the proportions across age group categories differed considerably (p < 0.01) with a tendency for the injured people to be younger, in particular among those aged 11–20 years (15.4 vs.

Main findings

The burden of having sustained RTIs was computed using a composite score comprising three elements that relate to the probability of subsequent long-term QoL. The main results showed that compared with non-injured individuals, RTC victims of any injury category had a higher risk of impoverished QoL one to four years after the crash.

This means that even relatively minor non-fatal injury incidents, and not only major events, can lead to a significant loss of QoL. Yet, we also observed that such

Conclusions

For policy making and regulation it is essential to pay attention to the fact that negative consequences of RTIs can be long-term and can arise even for apparently minor non-fatal injurious events. Sweden has been using “medical impairment” as a measure of health loss. Based on this indicator a 25% reduction goal of medically impaired individuals has been set by the year 2020. However, in terms of the actual health impact of RTIs, we think that it is important to produce, complement, or improve

Acknowledgement

This study was funded by the Swedish Transport Agency.

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