RESEARCH

Examination of Pneumonia Risks and Risk Levels in Trauma Patients With Pulmonary Contusion Carolina Landeen, MD ■ Hayden L. Smith, PhD

ABSTRACT Development of pneumonia in patients with pulmonary contusion can result in morbidity and mortality. This study examined the utility of a pneumonia risk tool for pulmonary contusion patients, which was originally developed using national level data. The study found a 21% prevalence of pneumonia diagnosis in pulmonary contusion patients at the examined level I trauma center, with patients in the high-risk group having 8 times greater odds for pneumonia diagnosis. The study also revealed increasing age and the use of mechanical ventilation as being significantly associated with pneumonia status. Early identification of risk factors for pneumonia could help direct clinician care strategies.

Key Words Lung injury, Mechanical ventilator, Pneumonia, Trauma

INTRODUCTION AND SIGNIFICANCE Lung injuries can result from various mechanisms, the most common being vehicular crashes and falls.1 In trauma patients, severe chest injuries are the second leading cause of death.2 Complications leading to fatality with lung injuries include multiple organ failure, persistent respiratory insufficiency, and the development of infections, such as pneumonia.3,4 Pulmonary contusion is a condition that can involve severe local and systemic immunodysfunction, facilitating infections including pneumonia.4 Development of pneumonia in patients with pulmonary contusion has been reported to range from 11.8% to 33%.5,6 Pneumonia in trauma intensive care unit (ICU) patients has been shown to quadruple and double ICU and hospital length of stay, respectively.7 Interestingly, pneumonia in this setting has not been associated with higher levels of early mortality.7,8 The importance of early prediction of complications in patients with pulmonary contusion motivated the develAuthor Affiliations: Internal Medicine Residency Program, University of Iowa–Des Moines (Drs Landeen and Smith); and Medical Education Services, UnityPoint Health–Des Moines, Des Moines, Iowa (Dr Smith). Conflicts of interest and source of funding: none declared. Correspondence: Hayden L. Smith, PhD, Medical Education Services, Iowa Methodist Medical Center, 1415 Woodland Ave, Ste 140, Des Moines, IA 50309 ([email protected]). DOI: 10.1097/JTN.0000000000000029

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opment of a scoring rubric used to predict pneumonia risk in patients diagnosed with lung contusion.5 Early identification of potential factors related to developing pneumonia can impact patient outcome by eliciting more rigorous treatments and further investigation into appropriate prophylaxis and management. The aim of this study was to examine the utility of a previously developed pulmonary contusion risk score for pneumonia5 that was developed using national level data. The primary objective was to test and validate the tool for predicting pneumonia in pulmonary contusion patients at a level I trauma center and determine its limitations. Secondary objective was to examine all other potential factors for pneumonia risk in this patient sample to better understand all possible strategies for addressing pneumonia. Study information may contribute to advancing detection and prevention of morbidity and mortality at a clinical level.

METHODS Study Design and Data Sources A retrospective observational study was conducted using trauma patient data from a level I trauma center in the Midwestern United States from January 2005 through December 2011. Patient characteristics and medical care data were collected from the hospital’s trauma registry, available medical and billing records, and the Clinical Quality Department. Pulmonary contusion patients were ascertained from the trauma registry and had an International Classification of Diseases, 9th Revision, Clinical Modification diagnosis of 861.2 or 861.3. Diagnosis was made by the attending physician in charge of the patient's care as stated in the medical record. Pneumonia status was determined by documentation in medical records, which included clinic assessments and/or an objective surveillance definition.9 Patients were excluded from the study if they were younger than 16 years, transferred to another facility on day 1, discharged without admission, or deceased on day 1. In addition, patients were excluded if discharged within 48 hours, based on the premise that 48 hours is the minimum amount of time required for hospital-acquired or ventilator-associated pneumonia to present.10 Variables that may assist in predicting pneumonia risk in pulmonary contusion patients have been revealed in previous research. These variables were determined WWW.JOURNALOFTRAUMANURSING.COM

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using a multiphase model building process based on data from the National Trauma Data Bank. Information on the development of these previously established risk factors for pneumonia in pulmonary contusion patients is presented in Table 1 and described elsewhere in greater detail.5 These risk factors included initial emergency department heart rate greater than 110 beats per minute, systolic blood pressure less than 110 mmHg, Glasgow Coma Scale (GCS) Motor score of less than 6, male gender, age greater than 41 years, body mass index (BMI) more than 40, patient sedation/intubation at the time of assessing GCS, and mechanical ventilation on day 1. In particular, patients were given points depending on the presence of these previously determined risk factors, with more points given to corresponding risk factors that were more strongly associated with pulmonary contusion. Points were summed and patient risk levels (ie, Low, Moderate, High) had been formed on the basis of these points. Patient medical records were reviewed for risk factor data and all other potentially applicable patient information associated with pneumonia status. Specifically,

TABLE 1

Scoring System for Pneumonia Risk in Pulmonary Contusion Patients

Risk Factors

Risk Score

Age, y 16-40

0

41-55

2

>55

5

Glasgow Coma Scale Motor Score Score 1 (age 16-55 years)

8

Score 2-5 (age 16-55 years)

6

Score 1 (age ≥ 56 years)

5

Score 2-5 (age ≥ 56 years)

3

Score 6

0

Sex (male)

2

Heart Rate ≥ 110 beats/min

2

Intubation/Sedation for GCS

1

Obesity (body mass index ≥ 40)

4

Systolic Blood Pressure < 110 mmHg

2

Ventilation (on day 1)

13

Overall Pneumonia Riska

Analysis Descriptive statistics were performed on patient data. Continuous variables were examined and reported with appropriate measures of central tendency (medians) and dispersion (interquartile ranges [IQR]). Categorical variables were reported with counts and percentages. Patient characteristics and risk factors were examined on the basis of pneumonia status using the Fisher’s exact test or the Wilcoxon rank sum test. Logistic regression was performed to examine risk level as an independent variable predicting the dependent binary variable of pneumonia status. Odds ratios for pneumonia based on risk levels were calculated with a 95% confidence interval (CI) from the logistic model. When appropriate, Bonferroni-corrected CIs were used to address multiplicity. Polychoric correlation between risk levels and pneumonia status was calculated with 95% CI. A classification table was constructed on the basis of the high-risk level representing a positive pneumonia status and the low-risk level representing a negative pneumonia status, with the criterion standard for pneumonia status being the presence of documented pneumonia in the medical record. The following values were determined using the classification table and were based on concordance or discordance of risk level and presence of documented pneumonia: true positives; true negatives; false positives; and false negatives. Also, using data from the classification table, sensitivity, specificity, negative predictive value, positive predictive value, likelihood ratio positive (LR+), and likelihood ratio negative (LR−) with 95% CIs were calculated. Finally, an overall multiple logistic model examining risk factors and all other relevant patient data was conducted to predict pneumonia status as the dependent binary variable. All variables were eligible for inclusion on the basis of clinical relevance and bivariate significance with multiplicative interaction terms examined. A final best fit parsimonious model constructed on the basis of a 0.05 level of significance for covariate inclusion. Respective adjusted odds ratios and 95% CI were calculated. Statistical tests were 2-tailed and based on a 0.05 level of significance. Statistical procedures were conducted with SAS 9.3 (SAS Institute, Cary, North Carolina).

Low

0-3

FINDINGS

Moderate

4-6

High

7-21

There were 10 962 trauma patients seen at the level I trauma center during the 7-year study period. Of these patients, there were 520 (5%) with a diagnosis of pulmonary contusion and 364 (3%) met inclusion criteria (Figure 1).

Based on summed risk scores.7

a

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in this study, risk factor refers to the variables previously establish in prior work along with the previously established risk levels. The study received institutional review board approval.

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Figure 1. Study sample (n = 364).

Study patients had a median age of 36 (IQR: 23-51) years and 73% were male. Injury type was blunt trauma in 98% of patients, with a median GCS Motor score of 6 (IQR: 5-6) and Injury Severity Score (ISS) of 24 (IQR: 1734). Prevalence of a pneumonia diagnosis was 21%. Characteristic differences between patients based on pneumonia status are presented in Table 2, with patients differing on sex, heart rate, GCS Motor score, ISS, Trauma and Injury Severity Score, mechanical ventilation (ie, patients intubated for general anesthesia and extubated in the recovery room were not considered positive for mechanical ventilation), length of ICU stay, length of stay, discharge status, and discharge location (P < .05). Comparisons between patients based on risk factors and pneumonia status revealed differences in GCS Motor JOURNAL OF TRAUMA NURSING

scores, sex, heart rate levels, intubation, systolic blood pressure levels, and ventilation on day 1 (P < .05; see Table 3). Median risk factor score based on summing individual risk factor scores was 5 (IQR: 3-8) versus 20 (IQR: 7-26) for patients without and with a pneumonia diagnosis (P < .0001), respectively. The majority of patients without pneumonia diagnosis had either a low- or moderate-risk level, while the majority of patients with a pneumonia diagnosis had a high-risk level. A trend test (P = .0001) and polychoric correlation revealed a positive increase (ρ: 0.52 [95% CI: 0.39-0.65]) between risk level and pneumonia status. Patients classified as highrisk level had 8.1 (95% CI: 2.5-26.6) times greater odds than low-risk-level patients for a diagnosis of pneumonia and these patients also had 5.8 (95% CI: 2.7-12.2) times WWW.JOURNALOFTRAUMANURSING.COM

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TABLE 2

Characteristics of Pulmonary Contusion Sample Patients (n = 364)a

Characteristic

No Pneumonia (n = 289)

Pneumonia (n = 75)

Pb

Sex (male)

201 (70%)

63 (84%)

.0133

Median age, y

35 [22-51]

40 [27-53]

.5141

Race

.2232

White

246 (85%)

70 (93%)

Black

18 (6%)

2 (3%)

Other

25 (9%)

3 (4%)

26.3 [22.9-31.8]

27.3 [24.1-31.9]

283 (98%)

74 (99%)

7 (2%)

1 (1%)

>.9999

Motor vehicle crash

202 (70%)

59 (78%)

.2435

Fall

33 (11%)

8 (11%)

Other

54 (19%)

8 (11%)

130 [116-142]

124 [108-146]

.3907

95 [81-110]

104 [90-119]

.0048

6 [6-6]

3 [1-6]

Examination of pneumonia risks and risk levels in trauma patients with pulmonary contusion.

Development of pneumonia in patients with pulmonary contusion can result in morbidity and mortality. This study examined the utility of a pneumonia ri...
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