Elsevier

Injury

Volume 43, Issue 1, January 2012, Pages 8-17
Injury

Review
Risk factors that predict mortality in patients with blunt chest wall trauma: A systematic review and meta-analysis

https://doi.org/10.1016/j.injury.2011.01.004Get rights and content

Summary

Background

The risk factors for mortality following blunt chest wall trauma have neither been well established or summarised.

Objective

To summarise the risk factors for mortality in blunt chest wall trauma patients based on available evidence in the literature.

Data sources

A systematic review of English and non-English articles using MEDLINE, EMBASE and the Cochrane Library from their introduction until May 2010. Additional studies were identified by hand-searching bibliographies and contacting relevant clinical experts. Grey literature was sought by searching abstracts from all Emergency Medicine conferences. Broad search terms and inclusion criteria were used to reduce the number of missed studies.

Study selection

A two step study selection process was used. All published and unpublished observational studies were included if they investigated estimates of association between a risk factor and mortality for blunt chest wall trauma patients.

Data extraction

A two step data extraction process using pre-defined data fields, including study quality indicators.

Study appraisal and synthesis

Each study was appraised using a previously designed quality assessment tool and the STROBE checklist. Where sufficient data were available, odds ratios with 95% confidence intervals were calculated using Mantel–Haenszel method for the risk factors investigated. The I2 statistic was calculated for combined studies in order to assess heterogeneity.

Results

Age, number of rib fractures, presence of pre-existing disease and pneumonia were found to be related to mortality in 29 identified studies. Combined odds ratio of 1.98 (1.86–2.11, 95% CI), 2.02 (1.89–2.15, 95% CI), 2.43 (1.03–5.72, 95% CI) and 5.24 (3.51–7.82) for mortality were calculated for blunt chest wall trauma patients aged 65 years or more, with three or more rib fractures, pre-existing conditions and pneumonia respectively.

Conclusions

The risk factors for mortality in patients sustaining blunt chest wall trauma were a patient age of 65 years or more, three or more rib fractures and the presence of pre-existing disease especially cardiopulmonary disease. The development of pneumonia post injury was also a significant risk factor for mortality. As a result of the variable quality in the studies, the results of the selected studies should be interpreted with caution.

Introduction

Blunt chest wall trauma does not involve any opening of the chest wall and can vary in severity from minor bruising or an isolated rib fracture to severe crush injuries on both sides of the thorax leading to potentially fatal respiratory compromise.52 Blunt chest wall trauma accounts for over 10% of all trauma patients presenting to emergency departments worldwide.53 Research has highlighted significant morbidity and mortality for the blunt chest wall trauma patient, with reported mortality ranging from 4 to 20%.38, 53 The patient with severe thoracic injuries will be managed in the Emergency Department by trauma and various surgical teams and intervention is dictated by the resuscitation protocol of the department.8 Disposition of chest injury patients from the Emergency Department is therefore straightforward when the patient requires immediate surgery or supportive mechanical ventilation.8 When the injury is not as severe, or associated injuries are not present, deciding which blunt chest wall trauma patients require a higher level of clinical input can be difficult. Clinical symptoms are not considered an accurate predictor of outcome following non-life threatening blunt chest wall trauma.15

Pape et al. developed a scoring system for guiding initial clinical decision making in the blunt chest trauma patient with multiple associated injuries however there are currently no evidence-based guidelines to guide patient management in the blunt chest wall trauma population with no associated injuries.35 Ahmad et al. suggested that a scoring system needs to be designed to evaluate the degree of injury following blunt chest trauma.1 Methods are required to assist identification of the patient who presents with non-immediate life threatening blunt chest wall trauma, but will develop complications within the following 24–72 h.1, 15 Evidence suggests that these patients can deteriorate up to a week after initial presentation to the Emergency Department28, 41 and elderly blunt chest wall trauma patients are particularly at risk of delayed deterioration.3, 42 The appropriate management of the blunt chest wall trauma patient with no immediate life threatening injuries has been an area of interest in previous research which has highlighted the difficulty in identifying the high risk patient in this population.30, 31, 40 Blecher et al. described a group of chest trauma patients who were considered suitable for ward management by the Emergency Department, of which 10% went on to require Intensive Care Unit admission with associated longer lengths of stay and higher rehabilitation requirements.8

Risk factors for mortality in the blunt chest wall trauma patient have been investigated previously in the literature and various outcome measures are used including mortality, morbidity and different aspects of resource consumption. When provided, definitions for these outcome measures vary in each study, leading to questionable validity and difficulty in comparison of studies. Given the inconsistent definitions for these outcomes, this study focussed specifically on the risk factors for mortality in blunt chest wall trauma patients as this is the most consistently measured and reported outcome measure. The aim of this review was to summarise the risk factors for mortality in the blunt chest wall trauma patient in order to assist in the identification of the high risk patient and facilitate decisions regarding the required appropriate level of care. For the purpose of this study, we defined blunt chest wall trauma as blunt chest injury resulting in chest wall contusion or rib fractures, with or without non-immediate life-threatening lung injury.

Section snippets

Search strategy

All methods used in this review followed the CRD13 PRISMA,34 and MOOSE47 guidelines. A broad search strategy was used in order to include all relevant studies. The search filter was used for Medline and Embase Databases and the Cochrane Library from their introduction until June 2010. The search term combinations were Medical Subject Heading (MeSH) terms, text words and word variants for chest trauma. These were combined with relevant terms for aetiological factors. The search terms are

Results

A total of 4326 citations were identified from the electronic searches and 25 citations through other sources. Following screening of the titles and abstracts using the two-step process, a total of 73 full-text citations was retrieved for detailed evaluation. No further citations were identified through the searches of grey literature. The experts in the field who responded suggested studies for inclusion that had been identified in the original search. Two non-English language studies were

Discussion

This systematic review was conducted in order to summarise the risk factors for mortality in blunt chest wall trauma patients who can normally be safely discharged from the emergency department, but will develop later complications. Klein et al. stated that controversy remains regarding methods to identify the mild to moderate blunt chest wall trauma group who develop late complications.28 Studies investigating only severe blunt chest trauma patients, such as intra-thoracic injuries were

Limitations

Systematic reviews of observational studies remain a contentious issue in research. Identification of potential forms of bias is important in observational studies, which are sensitive to publication bias and confounding. The results of this review are subject to publication bias as the studies with significant findings are more readily published in peer-reviewed journals than those without.21 There is also a tendency amongst authors to only present significant results.21, 47 The search

Conclusions

Patients who present with mild to moderate blunt chest wall trauma can normally be safely discharged from the emergency department with adequate pain control and education on pulmonary hygiene. A percentage of this patient group will develop late complications however no current guidelines exist to assist the emergency department physician in the recognition of this high risk blunt chest wall trauma patient population. In order to develop such guidelines or a risk stratification tool, the risk

Conflict of interest statement

The three authors of this study state that they have no conflict of interest.

Funding source

The Welsh Intensive Care Society: no involvement in study.

Acknowledgement

The Emergency Department, Morriston Hospital, Swansea.

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