CT scan incidental findings in trauma patients: does it impact hospital length of stay?

Introduction

Except for cardiac events and cancer, trauma remains one of the leading causes of morbidity and mortality in the USA. Based on the US Census Bureau, in 2009 there were 10.8 million accidents leading to over 35 900 deaths.1 Trauma is still the leading cause of death among teenagers and a major cause of morbidity and mortality among the elderly, which is a growing area of concern.2 The modern trauma centers rely heavily on CT scans for assessment of solid organ injuries. Besides providing information on acute trauma-related injuries, CT scans could also reveal pathologies not related to trauma called ‘incidental findings’, which may or may not require further investigation.3–6

The diagnosis and correct treatment of these incidental findings could have an impact on patient’s future health. The frequency of incidental findings varies from institution to institution4 7 8 as it depends on patient population, volume of trauma, type of trauma and resources available at the trauma center. The number of incidental findings based on previous published articles has been variable from 30% to as high as 53%.9–14 The aim of this study is to determine the frequency of incidental findings in a level 1 trauma center, hospital length of stay, any intervention performed during or after the admission and 1-year follow-up. The incidental findings will allow for development of a classification system that can be applied to these findings, which will help in their management, improve patient awareness and follow-up.

Methods

Result

One thousand charts were reviewed and 957 were selected. Forty-three charts were excluded due to incomplete documentation. Out of those 957, 385 patients (40%) were found to have incidental findings. A total of 560 incidental findings were found on CT scan reports and, of these, more than one-third of the patients had multiple incidental findings (144 patients, 37%). Table 1 lists the baseline patient characteristics and inpatient outcomes for overall group and subgroups of incidental and non-incidental findings. The mean age of all patients was 54.3±27.6 years; the age for patients with incidental findings was much higher compared with patients without, 62.0±22.3 years vs 49.2±29.5 years (p=0.0001), respectively. Patients aged >65 years totaled 44% of the study population and were found to have a significant number of incidental findings (53% vs 39%, p=0.0001). Of patient risk factors, cardiopulmonary disease was found in 51% of the overall study group, with a significantly higher number of incidental findings found in patients with cardiopulmonary disease than those without (58% vs 47%, p=0.0005). History of prior surgery was also significantly higher in patients with incidental findings when compared with those without (52% vs 43%, p=0.0045).

In trauma classifications, falls were most common (58%) followed by MVA (23%), assault (6%), pedestrian accident (6%) and others. Falls were proportionally greater in the incidental group (62% vs 55%). The overall mean ISS was 13.5±7.7. Between the groups, the mean ISS was higher in the incidental group by one point compared with the non-incidental group with significance (14.2±7.8 vs .13.1±7.7, p=0.0325).

The number of CT scans patients received were quantified and separated between the two groups. A total of 1820 CT scans of the head, chest and abdomen/pelvis were performed and reviewed. The number of scans between groups is shown in table 1. A high number of scans for the head, chest and abdomen/pelvis had incidental findings (92%, 62% and 96%, respectively) compared with non-incidental group (80%, 26% and 46%, respectively); each group comparison was highly significant (p<0.0001). A total of 337 findings (67% of all incidental findings) were identified on CT scans of the abdomen and pelvis, the most of all CT scans performed. The least number of incidental findings were identified on CT scans of the head (28 findings, 5%).

ICU admission was required for 28% of patients: incidental group 133 (35%) and non-incidental group 135 (24%) (p=0.0002). Overall hospital length of stay was 7.3±10.1 days, with 8.7±12.8 days taken by the incidental group to be discharged and 6.4±7.7 days by the non-incidental group (p=0.0012).

Table 2 lists all incidental findings reported in the CT scan reports. The findings are categorized by classes defined above: class 1—51 (9%); class 2—354 (63%) and class 3—155 (28%). The highest number of findings were in class 2 classification (did not require urgent intervention) followed by class 3 (findings requiring urgent evaluation) and class 1 (normal variants). Class 1 lesions were 51 (9%) of our incidental findings. Class 2 included all adrenal and thyroid nodules, pleural and lung nodules and all types of cysts affecting kidneys and liver which do not require immediate or urgent intervention, but do require an appropriate follow-up. A total of 354 findings were defined as class 2 (63%) and 155 findings were defined as class 3 (28%). The most common incidental findings were found in kidneys (25% of all incidental findings and 42% of the abdomen and pelvic CT scan findings). The second most common organ with incidental findings was lung with 76 incidental findings (14%).

Table 3 illustrates patient demographics for the incidental group according to different classifications. Patients with class 3 findings were found to have the longest hospital stays (9.8±17 days) followed by class 2 (9.0±11.3 days) and class 1 (7.2±6.9 days) without significance (p=0.1206). Age and age >65 years, when compared by classification were still significant.

Follow-up outcomes of the trauma admission were reviewed and only 99 (11%) patients had post-trauma follow-up visit in the trauma clinic (incidental group 36 (10%) and non-incidental group 63 (12%)). Review of patients who had surgery in the same hospital admission for incidental finding revealed that one patient with abdominal aortic aneurysm underwent surgical repair. One-year follow-up with social security index was performed to review vital status of patients discharged alive at the time of the study resulted with an overall mortality of 19% (168 patients, excluding the in-hospital deaths). In the subgroups, the 1-year mortality was higher in the incidental group at 22% (76 patients) compared with the non-incidental group at 17% (92 patients), after excluding the in-hospital deaths.

Seven biopsies were done to evaluate masses for malignancy. Six were negative for malignancy and one patient was positive.

Table 4 presents the multivariate model of adjusted analysis for the significant findings of age >65 years, history of cardiopulmonary disease, history of prior surgery and ISS. It was found that the length of stay remained significant after adjusting for significant confounders (8.7±0.48 vs 6.7±0.55, p=0.005). One-year mortality and ICU admission were not significant when adjusted for incidental findings.

Discussion

This study was conducted to evaluate the frequency, length of stay and follow-up on incidental findings in our trauma patient population and their disposition. These incidental findings were defined as pathologies not related to trauma, which may or may not require further investigation or intervention.8 9 These findings might be beneficial for earlier detection of diseases such as malignancy; however, it could also result in increased patient anxiety, length of stay and an impact on healthcare costs.8 12 13 20

Our study showed that the percentage of the incidental findings in retrospective chart review was 40% in our trauma patients. Not surprisingly, most of the findings were discovered in CT scans of the abdomen and pelvis; CT scans of the head revealed the least number of findings, despite being the most frequently done. Sixty-three per cent of findings were defined as class 2. These findings, when further investigated did not require immediate intervention or further diagnostic studies before discharge. However, given the frequency and relevance of the incidental findings, these findings should not be underestimated and some sort of follow-up is required. Therefore, the incidental findings should be communicated to the patient or their family members and documented in the chart.8 9 The association between the incidental findings and the gender in trauma population was reported to be different in various studies. Although Barboza et al 19 did not find any association, Barrett et al 14 and Pasluska et al 7 reported the incidental findings to be more frequent in female patients. Our study demonstrated a higher frequency of incidental findings in female populations (42%). Only one patient with an incidental finding on CT imaging required a surgery (abdominal aortic aneurysm repair) during the same admission. All other surgeries performed were trauma related.

What we also found is lack of documentation and lack of follow-up for these findings, which has a significant clinical and medico-legal ramification.9 13 Poor documentation has been described previously, which we believe may be due to focusing more on the injuries from the trauma, which is expected, and not paying attention to these incidental findings.7 9 12–14 Only 10% of our trauma patients had follow-up visits to our trauma clinic. To insure accurate documentation, a section was added in our history and physical, as well as our discharge instructions, which obligates the clinical staff to report whether or not incidental findings are found in our trauma imaging studies and the need for follow-up.13 14 Furthermore, a hard copy of the CT scan reports and imaging ‘CD’ should be provided to the patients to educate them about these findings and to prevent any further unnecessary or repeating imaging studies that might cause unnecessary increase in health cost.

A lot of studies have reported a scoring system or classification for these incidental findings per their clinical significance.3 9 10 12–14 We have designed a classification to better evaluate these findings, which will help with further management. This classification will act as a guideline that will allow appropriate follow-up and resource distribution. A good referral system by emergency department physicians and trauma surgeons should be developed for adequate follow-up.

Class 3 findings, the most clinically concerning category, represents 28% in our study. Class 3 findings were suspicious for malignancies, metastatic disease or vascular aneurysms, which might represent a life-threatening condition to the patient’s health. Also, steps should be taken to increase the patient’s knowledge regarding a normal anatomical variant or benign finding, like those in class 1, which may prevent future confusion or unnecessary investigations.

On the other hand, incidental findings increase the challenge and work load of physicians. During trauma management, there are many incidental findings that are not important during the initial trauma care, but still might be important for patient’s further health. Therefore, the clinical relevance of these findings needs to be weighed against the patient’s actual injuries and also against the patient’s future health. Early identification of incidental findings increases patient survival and decreases morbidity.12 However, overdiagnosis might lead to unnecessary diagnostic testing.13 Shetty et al looked at thyroid nodules found incidentally on CT scan.17 Of 230 patients who were found to have thyroid nodule, 118 underwent biopsy and 22% were found to be malignant. It has also been reported that 29% of incidentally discovered adrenal masses >3 cm in diameter were determined to be malignant.9 18 Even asymptomatic biliary or renal stones found on CT scan are helpful to patient’s physician or other healthcare providers in the future if these stones become symptomatic.14 In our study, we found 18 patients in the incidental group that were identified with otherwise normal anomalies listed as incidental by the radiologist based on dimensional review of the CT scan.

Another challenge in the management of these findings is patients who are discharged from the ED after completion of trauma evaluation but before the completion of official CT scan reports. Patients may be sent home based on preliminary negative CT scan for trauma injuries that later are amended with a report of incidental findings.14 21 Furthermore, a continued follow-up is the key in evaluating patient progress, trauma service equipped with a liaison service to review patient outcomes in quality control could advise and follow-up on these findings.

Finally, the hospital length of stay was noted to be longer for patients with incidental findings compared with those without (8.7 vs 6.4 days). This finding was further broken down into the classification system we created to look at the class distribution of the length of stay. Patients with class 3 findings had the longest length of stay, followed by class 2 and class 1 without significance. In class 2 and class 3, the mean length of stay was 9 days (9.0±11.3 and 9.8±17.0, respectively) and 7 days for class 1 (7.2±6.9 days). This could be explained by the need for more imaging studies and consultations to be done for patients with incidental findings that were identified. If patients in class 2 and class 3 were evaluated with our proposed classification, this length of stay of 9 days could have been stratified and reduced with an outpatient referral follow-up system in place. This also may have impact on increasing the healthcare cost, especially if the patient has a benign lesion that does not require any intervention.

Conclusion

Incidental findings are commonly found during CT imaging in trauma centers. The rate of incidental findings (40%) in our center is in line with the national range, which is between 30% and 53%. Appropriate documentation, communication and follow-up of these incidental findings is necessary. A classification system for these findings practiced nationwide will aid in categorizing the urgency of further follow-up, once a trauma emergency has been stratified. This will help decrease hospital length of stay and overall healthcare cost.