Trauma in a Scandinavian urban region : epidemiological aspects on risk factors and outcome

Trauma as a disease is a global health problem and for patients surviving the initial injury and early resuscitation phase, later complications contribute largely to morbidity and mortality. Awareness of risk factors, early recognition and appropriate treatment of complications are likely to have a significant influence on outcome. Early identification of patients at risk may contribute to optimising initial resuscitation, intensive care and long-term outcome.

This thesis is based on four studies using epidemiological data from local and national registries. The aims of this thesis were to study incidence and risk factors for complications and mortality in severe trauma and the influence of socioeconomic factors and comorbidity on the risk of becoming a trauma victim.

Study I was a cohort study of 164 trauma patients admitted to the central intensive care unit at the Karolinska University Hospital, Stockholm. We found an incidence of multiple organ failure, acute lung injury and severe sepsis of 40.2%, 25.6% and 31.1% respectively. 30-and 90-day post-injury mortality was 10.4%. Intensive care unit-complications and death were not uniformly affected by the different risk factors.

In study II we investigated the influence of gender and comorbidity on 30-and 360-day survival of individuals registered in the trauma registry at Karolinska University Hospital, Stockholm between January 2005 and August 2008. In addition we evaluated survival over time in relation to the general population. The influence of gender and comorbidity on outcome after trauma differed over time. Male gender was an independent risk factor for mortality at one year but not at 30-days post injury and the effect of gender seemed to be restricted to elderly patients. The presence of comorbidity became a significant risk factor beyond 30 days after trauma. A persistent excess mortality in comparison to the general population was seen among men one year after trauma, standardized mortality ratio 3.8 (95% CI 2.8 - 5.1).

Our aim of study III was to report the overall incidence of pneumonia in intensive care unit-treated trauma patients and to investigate risk factors for development post injury pneumonia following severe trauma. The study cohort consisted of 322 trauma patients admitted to the central intensive care unit at the Karolinska University Hospital, Stockholm between February 2007 and July 2011. The incidence of pneumonia was 26% during their first 10 days in the ICU. Reduced consciousness was an independent risk factor for development of pneumonia after severe injury.

Study IV was a case-control study, cases (n = 7382) were defined as all patients 15 years or older registered in the trauma registry with a first trauma admission between January 2005 and December 2010. A random selection of 36760 age, gender and municipality matched controls were extracted from the Total population registry. Our aim was to study the influence of socioeconomic factors and comorbidity on the risk of becoming a trauma victim. Level of education and income as well as substance abuse, psychiatric, and somatic comorbidity were all independent risk factors for trauma. Active substance abuse strongly influenced the risk for trauma and had a time dependent pattern.

List of scientific papers

I. Early predictors of morbidity and mortality in trauma patients treated in the intensive care unit. Brattström O, Granath F, Rossi P, Oldner A. Acta Anaesthesiol Scand. 2010; 54: 1007–1017.
https://doi.org/10.1111/j.1399-6576.2010.02266.x

II. Time dependent influence of host factors on outcome after trauma. Brattström O, Larsson E, Granath F, Riddez L, Bell M, Oldner A. Eur J Epidemiol. (2012) 27:233–241.
https://doi.org/10.1007/s10654-012-9651-4

III. High incidence of post-­‐injury pneumonia in intensive care-­‐treated trauma patients. Hyllienmark P, Brattström O, Larsson E, Martling C-­‐R, Petersson J, Oldner A. Acta Anaesthesiol Scand. 2013; 57: 848–854.
https://doi.org/10.1111/aas.12111

IV. Socioeconomy and comorbidity as risk factors for trauma. Brattström O, Eriksson M, Larsson E, Oldner A. [Manuscript]