Sickness absence, disability pension, and permanent medical impairment among car occupants injured in a crash

Abstract

Background: Health loss in the road transport system is a major global public health problem, with approximately 1.35 million people killed annually, and it is also the fifth leading cause of overall burden of disease. Based on the Vision Zero, fatal or serious injuries within the road transport system are unacceptable. This thesis presents a new perspective of health loss after a car crash by examining the short- and long-term situation among people injured, in terms of sickness absence (SA) and disability pension (DP) and relating them to permanent medical impairment (PMI), the definition of serious injury used in Sweden. The overall aim was to generate knowledge about SA, DP, and PMI among injured passenger car occupants of working age.

Methods: Four register-based studies (I-IV) were conducted, based on microdata linked from four Swedish nationwide registers. In studies II-IV also data from the Folksam Insurance Group was used, including reported car crashes. Study I was cross-sectional and included injured car occupants who had inpatient or specialized outpatient healthcare after a crash in 2010 (N=9427). Studies II-IV were prospective cohort studies of individuals reporting injuries from car crashes to Folksam. Study II included 64,007 car occupants injured in 2001-2013. Study III (N=63,358) and IV (N=14,363 front-seat car occupants with symptoms of whiplash associated disorders (WAD) after rear-end crashes) used sub cohorts of Study II, and calculated net days of SA/DP per year in relation to the crash. Associations were assessed with multivariable logistic regression (I-IV). SA spells ≤14 days were not included.

Results: Among the inpatient and specialized outpatient healthcare patients injured in a car crash, 9% were already on SA/DP at the crash, while 10% had a new SA spell in direct relation to the crash. Among individuals reporting injury to Folksam, 2% had a new DP two years after the crash, 8% had injuries resulting in PMI. Among occupants with long-term WAD (symptoms >4 weeks) and occupants with injuries resulting in PMI, the mean annual net days of SA/DP increased substantially after the crash. In these groups, the number of SA/DP days remained high for several years after the crash. A distinct trend showed that the proportion granted DP increased with increasing PMI grade. The safety level of the car had significant importance for the future SA/DP situation and if the injury resulted in PMI. Occupants in older cars were more likely to have >180 days SA/DP in year two and four following the crash and were more likely to have an injury resulting in PMI, by up to three times, when compared to occupants of newer cars. Occupants of cars rated 2-3 stars by Euro NCAP were 40% more likely to have >180 days SA/DP in year two, compared to those in cars rated 4-5 stars. Furthermore, women reporting WAD after a rear-end crash in cars fitted with whiplash protection systems were less likely to have PMI and long-term WAD compared only to injured women in older cars without such protection system. Men injured in cars with whiplash protection systems were less likely to have long-term WAD and PMI compared to injured men in both older and newer cars without such protection system. They were also less likely to have >90 days SA/DP in year two, compared to men in older cars without systems. In general future SA and DP were also more common among those with previous SA.

Conclusions: Injuries resulting in PMI reflected the future situation of those injured in a crash in terms of higher SA/DP after the crash. Associations were found between car safety and SA/DP following the crash. The results indicate that the whiplash protection systems benefitted women to less extent than men. Previous SA/DP needs to be taken into consideration when studying SA/DP following a crash.