Analyses of Preventable Deaths by Mechanism of Injury Among 13,500 Trauma Admissions

C. GENE CAYTEN, M.D., M.P.H., WILLIAM M. STAHL, M.D., NANAKRAM AGARWAL, M.D., M.P.H., 'and JANE G. MURPHY, PH.D.

Preventable deaths (PD) were evaluated by mechanism of injury for 13,500 trauma admissions to eight hospitals over 2 years. There were 42 (3.3%) hospital deaths. Preventable deaths were analyzed by time of death, anatomic site of injury, and mechanism; penetrating (PEN) and blunt with low fall (LF) injuries were considered separately. Preventability of death for patients with probability of survival of less than 0.5, "unexpected deaths," after penetrating and blunt injuries, was determined by consensus of three trauma surgeons. Twelve per cent of deaths were found to be possibly preventable. The incidence of preventable deaths did not differ significantly across groups. Factors in preventable deaths varied by injury cause: delays in operation, PEN (50%), and blunt injury patients (48%); management errors, blunt (52%) and LF (84%); and technical errors, PEN (37.5%). Median times to death were significantly different by cause of injury: PEN, 3 hours; blunt, 13 hours; and LF, 3975 hours. Problems were identified in the hospital care of patients, especially those with LF, leading to sepsis and multiple organ failure. I N GENERAL, PREVENTABLE death studies have been

performed to assess factors that, if remedied, could result in increased survival rates among injured patients. In 1985, Cales and Trunkey' reviewed 29 preventable death studies and found that they fell into two general groups: those that evaluated care where a trauma system did not exist, and those that assessed the impact of a systematized approach to trauma care. Of the 29 studies reviewed, 20 focused entirely on motor vehicle crash patients, whereas several focused only on abdominal injuries.2'3 Since 1979, there have been only two studies that included trauma of most causes; both were from San Diego County.4'5 The present study included hospitalized adult deaths from all causes except bums. Presented at the I 1I1 th Annual Meeting of the American Surgical Association, April 1 1-13, 1991, Boca Raton, Florida. Supported in part by Grant #R49CCR202487 from the Centers for Disease Control, Atlanta, Georgia entitled "EMS System Factors Effects On Trauma Survival." Address reprint requests to C. Gene Cayten, MD, Department of Surgery, Our Lady of Mercy Medical Center, 600 East 233rd Street, Bronx, NY 10466. Accepted for publication April 23, 1991.

From the Institute for Trauma and Emergency Care, New York Medical College, Valhalla, New York

There have been many variations in the designs of preventable death studies. Some used stratified samples,6 others used complete samples7; some used explicit criteria8 and others implicit criteria.9 In this study the American College of Surgeons Committee on Trauma TRISS method was used to identify patients whose deaths were considered to be unexpected.'° A panel of trauma surgeons then evaluated these unexpected deaths to determine which were possibly preventable. Methods

Setting and Selection of Cases The study was conducted by the Institute for Trauma and Emergency Care (ITEC) at the New York Medical College (NYMC). Eight hospitals, all affiliates ofNYMC, participated in the research. Hospitals ranged in size from 200 to 813 beds. Three of the eight hospitals were officially designated level I trauma centers. Average numbers of trauma admissions per month ranged from 32 to 248, whereas average numbers of adult major trauma admissions eligible for the study ranged from 12 to 75 per month. Logs of all emergency department admissions in each hospital were reviewed by one of three trained nurse-abstractors. Patients were included if they either died or stayed in the hospital for 48 hours or more. Patients with major bums or only distal fracture (fractures below the knee or elbow) were excluded. Data Collected A study record was opened for each patient on his or her identification as eligible. Information from prehospital

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and emergency department records was abstracted at that time and was entered on standardized forms. The complete hospital record was reviewed after the patient's discharge, and final information regarding the patient's stay and condition at discharge were recorded. A wide range of data elements were collected regarding the care of each patient. For the purpose of this paper, important elements included demographic data, information regarding the cause of injury, and trauma diagnoses required to calculate the Abbreviated Injury Score (AIS)," Injury Severity Score (ISS)," Revised Trauma Score (RTS),12 and the probability of survival (Ps) using the TRISS method, ISS, RTS, and age.'0 Data concerning comorbidity and complications also were collected. Assessments of the preventability of death were made by reviewing the entire study abstract. The Abbreviated Injury Score (AIS) assesses injury severity on a scale of 1 (minor) to 6 (fatal) in each of several body regions." Scores are subjective assessments of severity made by expert raters. Ratings are completed on the basis of reviewing emergency department and hospital records. Each of six regions is scored, with the highest AIS value given to any injury in that area. Abbreviated Injury Score values for the three highest scoring body regions then are squared and summed to form the ISS. In this study AIS codes were assigned on the basis of the assessments of trained nurse-raters. American Association of Automative Medicine (AAAM)-1985 coding guidelines were followed." These generally parallel the guidelines used by the American College ofSurgeon Major Trauma Outcome Study (MTOS) guidelines for 1988.'3 Three differences between MTOS coding and ours deserve description, however. Under MTOS, initial loss of consciousness is not scored, named vessel lacerations (not further specified) are coded as "major," and hemomediastinum is not coded but is used to upgrade. Using AAAM guidelines, we scored initial loss of consciousness, gave a lower code to named vessel lacerations (not further specified), and coded hemomediastinum. To our knowledge there have been no studies of the effect of such differences in guidelines on AIS scores; however it seems unlikely that the effect is great. The RTS includes three physiologic parameters (Glasgow Coma Scale [GCS] systolic blood pressure, and respiratory rate) recorded soon after the patient's injury, generally in a prehospital or emergency department setting. 12 The coefficients used in the formula were developed using regression analyses based on data for 2000 Washington Hospital Center patients and tested using information concerning the more than 25,000 patients in the

MTOS.'° The TRISS methodology, also developed by Champion et al.,'2"14 combines the ISS, the RTS, and age to produce a Ps score.'0 Regression coefficients were derived from

511

data concerning the 26,000 patients in the American College of Surgeons Major Trauma Outcome Study (MTOS). The formula is Ps = 1/(1 + e - b), where b = bO + bl (RTS) + b2 (ISS) + b3 (age). Age is dichotomized as 0 for patients under 55 years and 1 for patients 55 or older. Separate sets of regression coefficients were developed for blunt and for penetrating injury groups. A z score is used to determine whether differences between the number of observed deaths within any given group of patients is significantly different from the number predicted. A negative z score indicates an excess of observed over predicted deaths. An M score accompanies each z score and indicates whether there is a reasonable match with respect to the mix of injury severity between the test data set and the MTOS set; an M score of at least 0.88 is considered desirable.

Analyses Analyses proceeded in five stages. First patients for whom full data required to compute Ps were available were compared with those for whom information was missing, using chi square and t test to evaluate the significance of differences. Second the reliability of AIS coding among raters is critical to the generalizability of results. Following the method developed by MacKenzie et al.,'5 kappa and weighted kappa were used to evaluate levels of agreement with regard to AIS coding, and the intraclass correlation coefficient was used to assess the reliability of ISS coding. In the last two sets of analyses, patients were classified by cause of injury: penetrating (including gunshot, stab, and bite wounds), blunt (including motor vehicle crashes, falls from heights, and assaults with blunt objects), and low falls (on level surface or from low steps identified by E-codes 880.9, 884.2, 885.0, 888.0). (Although other studies have analyzed motor vehicle crash patients separately, we found no significant differences in death, unexpected death rates, or preventability between these patients and those falling from heights or assaulted with blunt objects; thus the categories were combined.) Comparisons among groups with respect to selected demographic and injury characteristics were made using t tests, analyses of variance, chi square tests, and z scores. "Unexpected deaths" were defined as patients who died of any injury cause with a Ps of 0.5 or greater. A panel of three experienced general surgeons (CGC, WMS, NA) reviewed a detailed abstract for each unexpected death and independently evaluated whether the death was "possibly preventable" (hereafter "preventable"). Three general surgeons were chosen for the review panel based on the recommendation of Lowe et al., who reported difficulties with an interdisciplinary panel.8 The panel of surgeons then met, reviewed each death, and arrived at a consensus for each case. All unexpected deaths were reviewed for

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512

penetrating and blunt injury patients. Among low falls patients, previous research'6 has suggested a strong association between three comorbidities-anemia, chronic obstructive pulmonary disease (COPD), and congestive heart failure (CHF)-and death. Thus low falls patients with unexpected deaths and any of these three comorbidities were unlikely to be deemed unpreventable and were not reviewed. Abstracts for low falls patients with unexpected deaths and neither COPD, CHF, nor anemia were reviewed for preventability. Unexpected deaths and preventable deaths then were compared in terms of cause of injury, cause of death, and survival patterns. Results

The study included 13,500 adult patients admitted from July 1, 1987 through June 30, 1989. As Figure 1 shows, 5686 (42.1 %) met the eligibility criteria for abstraction. Most of those not included had distal fractures or dislocations, or were discharged in less than 48 hours. Some element or elements of data required to calculate the first emergency department RTS portion of the Ps were missing for 68 (1.2%) of the 5686 cases. Most of these cases were interhospital transfers for whom one or more value needed from the first hospital emergency department were not included in the medical record of the receiving hospital. In general these patients were injured in motor vehicle crashes (52.9%), and were somewhat more severely injured than the patients analyzed, as evidenced by their higher mean ISS values (16.7 vs. 12.2). There was no significant difference in death rates between those with versus

Ann. Surg. * October 1991

those without Ps values. Of the 5618 patients with Ps values, 421 (7.5%) died, and four (5.9%) of those without Ps values did not survive to hospital discharge. Interrater agreement between pairs of nurse-raters with regard to AIS and ISS coding was tested for 72 cases. For AIS coding, kappas ranged from 0.64 to 0.74; weighted kappas ranged from 0.68 to 0.79. The intraclass correlation coefficient used to evaluate the reliability of ISS coding was 0.78. These results are comparable to those reported by MacKenzie et al.,'5 and suggest very good agreement among raters. In the overall sample, 20.5% (1151) of patients sustained penetrating injuries, whereas 34% (1913) had low falls, and nearly 46% (2554) suffered other blunt injuries. Among the 421 patients who died, and who constituted the effective sample for this study of preventable deaths, 28% had penetrating injuries, 30% low falls, and 42% other blunt injuries (Fig. 2). Mortality rates ranged from 6.7% among low falls patients and 6.9% among blunt injury patients to 10.2% among those having penetrating injuries. On average penetrating injury patients who died were the youngest (31.8 ± 11.4 years), whereas low falls patients who died were the oldest (82.7 ± 6.8 years) (Table 1). Average ISS values were highest among those dying of blunt injuries (37.2 ± 15.4) and lowest for the low falls groups (11.8 ± 6.8). The mean RTS was lowest for the penetrating injury group (3.1 ± 2.8) and highest among those dying from low falls (7.4 ± 1.3). Mean Ps values calculated using the TRISS method were 0.33 for those dying of penetrating injuries, 0.43 among blunt injured patients, and 0.91 for those having low falls. Significant

DiSchar-gd Alve and Hos-Itzed 4 48 Hour 30% 42%

FIG. 1. Adult trauma admissions (July 1, 1987-June 30, 1989).

Distal Dlcains/Fa'X 22%

3.2% Burns

misc.

4%

2%

TOTAL ADULT TRAUMA ADMISSIONS 13,500 TOTAL ABSTRACTED 5,686

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BY MECHANISM OF INJURY

421/5618*7.5% MORTALUTY RATE LOW FALLS PENETRATiNG 28.0% 30.3% 115/1151u10.3%4 .,

125/19156.7%

BLUNT 41.7% *

Mortat

rates were

175/2550s9%

slglantly

dent _ao causes of h*wy (p.0004)

FIG. 2. Cause of injury.

and negative z scores for the penetrating injury and low falls groups indicated that there were more deaths than expected on the basis of the MTOS in those groups. The z score for the blunt injury group was not significant. Figure 3 shows proportions of deaths that were unexpected (Ps 2 0.5) and that were deemed preventable by the panel of surgeons. Nearly 55.3% ofdeaths overall were unexpected, whereas 11.9% were deemed preventable by the physician panel. Unexpected death rates ranged from 28.8% among penetrating injury patients to 45.7% among blunt injury patients and 93% among those with low falls (Pr < 0.05) (Fig. 4). The preventable death rates were 6.8% for those with penetrating injuries and 13.1% for those with blunt injuries. The abstracts of 69 (53.9%) low falls patients without COPD, CHF, or anemia were reviewed for preventability. The deaths of 19 (14.8% of all low falls patients) were held to be preventable. Differences in rates of preventable deaths were not statistically significant across groups. Most unexpected deaths among penetrating and blunt injured patients were related to hemorrhage and brain injury (Fig. 5). Sixteen of thirty-four unexpected penetrating injury deaths were related to hemorrhage; four (25%) were deemed preventable. Three of seven (42.9%) deaths among penetrating injury patients with sepsis/ multiple organ failure were considered preventable.

Among blunt injury patients, over half of the unexpected deaths were related to CNS; ten (22.7%) were deemed preventable. Eight of 17 (47.0%) deaths among blunt injury patients with sepsis/multiple organ failure were held to be preventable. Approximately half of the unexpected deaths among low falls patients were related to cardiovascular diseases; 1 1 (31%) were deemed preventable. The high unexpected death rate (93%) among low falls patients relates to the singular nature of this group. Over half suffered hip fractures and an additional 13.5% had neck, trunk, or other relatively minor skeletal injuries (Fig. 6). These are injuries that produce relatively low ISS valTABLE 1. Characteristics of Patients Who Died

Variable

PEN

Blunt

Low Falls

(118)

(175)

(128)

Age(mean + SD) 31.8 ± 11.4 43.4 ± 19.6* 82.7 ± ll.9t ISS (mean + SD) 30.3 ± 12.0 37.2 ± 15.4* 11.8 ± 6.8t 7.4 ± 1.3t 3.9 ± 2.8* RTS (mean + SD) 3.1 ± 2.8 0.33 ± 0.36 0.43 ± 0.38* 0.91 ± 0.20t Ps (mean + SD) -9.34 -1.63 -2.64 Z-score 0.88 0.98 0.95 M-score *

p < 0.05 PEN versus blunt.

t p < 0.05 LF versus PEN and blunt. PEN, penetrating injury; ISS, Injury

Severity Score; RTS, Revised

Trauma Score; Ps, probability of survival.

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Ann Surg. * October 1991

*.:_}

FIG. 3. Classification of deaths.

11.9% ues, high RTS values, and thus high Ps values. The comorbidity and complication rates within this group, however, were high. Low falls patients were significantly more likely than either penetrating or blunt injury patients to have CHF, COPD, anemia, hypertension, or renal failure

(Fig. 7), whereas mean numbers of complications were 3.0, 0.6, and 1.4, respectively (Pr < 0.01). This combination of high Ps values and high rates of complications and comorbidities largely explains the high unexpected death rate.

200

(A Z 150 Iii

6.8%

1 8

OL

26.8%

JL 100 84(71.2%)

o

150

z 0

PENFTRATNG BLUNT EXPECTED m UNEXPECTED / Ps 4 50% 1_ Ps 50%

LOW FALLS

PREVENTABLE

PANEL REVEW

FIG. 4. Classification of deaths by cause of injury.

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ANALYSES OF PREVENTABLE DEATHS BY MECHANISM OF INJURY

515

140 120

100

s0

40

34

a

0

PW4EThATINS

manS

5

LOW FALLS

KUNT [preventable UWSAde6au dLAa Elex[]Cnd

FIG. 5. Unexpected and preventable deaths by cause by death.

Three broad classes of reasons for preventable deaths were identified (Fig. 8): delays in operation, management errors, and technical errors. Most (58%) preventable deaths resulted from management errors; an additional 34% were caused by delays in operations, and 8% by technical errors. Delays in operations occurred most frequently among patients with head injuries, and, secondarily among patients with penetrating chest injuries. Errors in management occurred primarily among those with low

falls or other blunt injuries who had prolonged hospital stays. The errors involved the inability to prevent and effectively treat complications such as pneumonia, pulmonary embolus, and organ system failure in patients who should have recovered from their injuries. Eleven of these developed pulmonary emboli, whereas eight bedridden patients survived their injuries but developed pneumonia, sepsis, respiratory failure, or acute renal failure. Technical errors occurred primarily among pene-

Neck/Trunk Fx13.5% Limb Fx 7.0% sower Limb Fx 5.1%

Hip Fx 53.9% FIG. 6. Primary diagnosis for lowfall patients (N = 1931).

W.

........... .........

......

-

Oh ^

hItracranlal 10.6% 2.8% Contusin Sprahi/Straha 1.1% 0.9% htmal Dilocation 0.49S 1.796 Other

CAYTEN AND OTHERS

516

Ann. Surg. * October 1991

15.6

5io 4.

11.4 ..

10.6

fil.

0S15

S_ *-

1-

0 Woqw

-r_l **.

t.. I%

".o low

.

i.

.1,11

::.%...,.

Fic. 7. Prevalence of pre-existing conditions by cause of injury.

trating injury patients and included failure to control femoral vein transection, delayed hemorrhage from a tracheostomy site, failure to recognize and control a hepatic artery injury, and an innominate vein injury secondary to catheter insertion.

Deaths are classified with respect to injury cause and time to death in Figure 9. Mean times to death were significantly different among groups (Pr < 0.05). Penetrating injury patients who died survived an average of 55 hours (median, 3 hours). Over three quarters died within 24

PENTRATING

BLUNT

(NWe)

(N23)

47.5

WAiQ

5t2%

1t5%

LOW FALLS (N19) &3% MM%

DELAY

OPERATION IN MANAGEMET ERROR 1 TENICAL ERROR *

84.2% FIG. 8. Reasons for preventable deaths.

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ANALYSES OF PREVENTABLE DEATHS BY MECHANISM OF INJURY

517

100 91

LI]

PREVENTABLE

77

1.

UNEXPECTED

90

l;.

I...

cn

80

IL w H

60

;:

,; rl

* EXPECTED

40 F

m z 20 F

O

I. 424HRS 24HR-2WK 22WK

PENETRATING

BLUNT

424HRS 24HR-2WK t2WK

LOW FALLS

FIG. 9. Classification of deaths by cause and time to death.

hours, whereas just 4.2% died after 2 weeks. Early deaths tended to be due to exsanguination or gunshot wounds to the head. Fifty-six per cent of unexpected and three of eight preventable penetrating injury deaths occurred within the first 24 hours of hospitalization. Among patients dying of blunt injuries, the median hour of death was 12.75, with 53% dying within 1 day and nearly 20% dying after being hospitalized for more than 2 weeks. Forty per cent of unexpected blunt injury deaths occurred between 2 and 14 days after hospitalization; just one preventable death occurred within the first 24 hours of hospitalization. Low falls patients had the longest mean and median times to death (634 and 396.5 hours, respectively). Fifty-seven per cent of these patients died more than 2 weeks after entering the hospital. Nearly 60% of unexpected deaths and 53% of preventable deaths occurred after 2 weeks of hospitalization. Deaths within this group were related primarily to sepsis/multiple organ system failure and to cardiovascular disease. Discussion Preventable death studies have been done in many ways by different investigators throughout the country.' Sample selection methods have varied widely: many studies focused primarily on motor vehicle crash patients2'6'17"8 whereas others included only pediatric injuries.4 In some instances deaths occurring in a short period in a given

area have been studied,'9 whereas in others, longitudinal stratified samples have been drawn.6 Some studies have focused on hospital deaths,20 and others have included prehospital deaths.2 The sizes of panels deciding on preventability have varied (from 3 to 35) and, although most have included only surgeons, the mix of specialties represented has varied. Definitions of "preventability" also have differed. Frames of reference for preventability have varied from optimal care, to the level of care "generally expected" in the community, to the level available "if the injury occuffed in the accident department of a general hospital." Criteria for preventability ranged from completely implicit to explicit. Data sources have varied from the use of all hospital and prehospital records, to the inclusion of only hospital or only autopsy records.2' The definition of consensus among panel members has differed; one study required agreement between two of six panel members,8 whereas most required a simple majority.' The wide disparity among methods has resulted in a lack of comparability among results. If preventable death studies were to be standardized with regard to several of these parameters, their usefulness as an evaluative tool within and among sites would be enhanced greatly. Several years ago the American College of Surgeons Committee on Trauma (ACS/COT) adopted a quality assurance protocol based on the MTOS.22 The protocol suggested that the TRISS method be used to identify pa-

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CAYTEN AND OTHERS

tients whose combinations of injury cause, anatomic and physiologic status, and age yielded a Ps of 0.5 or greater but who died, viz., who had at least a 50% chance of living but who died. These cases then would be considered "unexpected deaths." It was further recommended that detailed peer review of such deaths be conducted because it is within this group that deficiencies in individual patient care and in trauma systems could be most readily identified.22

The research reported is the first to tie the ACS/COT quality assurance recommendations to a preventable death study. In it the deaths of patients whose Ps was less than 0.5 were considered to be expected whereas those who died with a Ps of 0.5 or greater were deemed unexpected. Thus an objective severity scale was used as an audit filter. Preventability then was assessed on a case-bycase basis, with one exception-unexpected deaths among low falls patients with either COPD, CHF, or anemia were considered to be unpreventable and not reviewed. The results of the study confirm and expand those reported by others. Shackford et a123 reported on 224 nontrauma hospital deaths and 541 trauma center deaths. At the nontrauma center hospital, 7.6% were considered frankly preventable, whereas at the trauma center there were 2.0% such patients. Among the explicit guidelines used were: nonpreventable patients should have Ps < 0.25, potentially salvageable 0.50 > Ps > 0.25, and frankly preventable Ps > 0.50. Thus, Shackford and co-workers' frankly preventable group corresponds to our possibly preventable group. They found that preventable deaths occurred at nontrauma hospital because the severity or multiplicity of injuries was not appreciated. Preventable deaths at trauma centers were due to an error in either judgment or technique. We did not attempt to compare trauma center with nontrauma because three of our five nontrauma centers were comparable in capabilities to level II trauma centers, which are considered trauma centers in the Shackford study. The death of only 1 of 12 (8.3%) penetrating injury patients, who died of central nervous system (CNS) damage was found to be preventable; this result is consistent with Gennarelli and co-workers'13 report that the most lethal wound is a gunshot wound to the head, yielding a mortality rate of 68%. Others23' 17"18'24'25 have reported 25% to 53% preventable death rates among patients in motor vehicle crashes. In the present research, the motor vehicle and other blunt injury patients were very similar and were analyzed as one group. The preventable death rate was just over 13%. Over half (44 of 79) of the unexpected deaths were related to CNS injuries. The fact that just 10 were held to be preventable relates in part to deficiencies in the ISS. For example patients with isolated severe head injuries have an AIS of 5 and an ISS of 25. Even with a low Glasgow Coma Score, such a patient is likely to have a Ps of greater

Ann. Surg. * October 1991

than 0.5 and thus be an "unexpected" death. Delays in operations and poor management were the major causes of preventable deaths in this group. One group of patients notably absent among these blunt injury deaths were patients dying from ruptured spleens. In several studies from the 1960s and 1970s, delays in diagnoses and operations on ruptured spleens accounted for a significant proportion of preventable deaths.2'3"7'26 In addition many of the earlier preventable death studies of motor vehicle crash victims demonstrated significant deficiencies in recognizing and appropriately managing patients in hypovolemic shock. This study shows that preventability is shifting to longer-term management issues of these patients. Low falls patients generally have been excluded from preventable death studies because they often are considered not to need the resources of a trauma center. Fitts et al.7 performed an autopsy study of all trauma deaths in Philadelphia in 1969. They found that 26% of deaths were associated with hip fractures; 30% of patients in the present study died of low falls. These results support Fitts and co-workers' overall conclusion that the most common cause of death from injury was a fall by an aged patients. Fitts et al. also reported that 15% of all patients studied died from pulmonary emboli. We found 47% of our preventable low falls deaths were from pulmonary emboli. The low falls patients mortality rate is also profoundly effected by age and comorbidity. Morris et al.27'28 found that, starting at age 40 years, death was independently and adversely influenced by male gender and the presence of both pre-existing medical disease or injury to head or abdomen. Morris et al. found that congenital coagulopathy, cirrhosis, ischemic heart disease, and COPD and diabetes increase the mortality rate in all patients. We found that in hip fracture patients, congestive heart failure, COPD, and anemia increased mortality rate. The duration of survival of patients with various injury causes was found to be consistent with general experience. Thus penetrating injury patients tended to die early, 76% in less than 24 hours, or to be discharged alive. Approximately half of blunt injury deaths occurred within the first 24 hours, but nearly 20% were late deaths. Shackford et al.,5 in a study population that was close to 70% blunt trauma, found that 75% died in less than 24 hours. Low falls patients rarely died acutely of their rather minor injuries, but instead died after 2 weeks largely because of complications or comorbidities. The study has several strengths and limitations. Patients from eight hospitals (3 trauma centers and 5 nontrauma centers) with any injury cause were included. The hospitals were chosen for convenience, however, and, because the study was not population based, the results do not necessarily represent a broader population. All injured patients-except those with burns or only distal fractures-

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who died or who stayed in the hospital for at least 48 hours over a 2-year period were included. All medical records-prehospital, hospital, and autopsy recordswere used to abstract data. The study also is the only preventable death analysis to document the reliability of the data abstracting process. Prehospital and autopsy data, however, were not available in great detail; such information could have provided a more objective basis for some decisions relative to preventability-particularly with respect to care in the field. In addition we found, as others have suggested, that the longer the patient lived the more difficult it was to determine the preventability of death.2 Our review panel concluded that, particularly among low falls patients, review of the entire medical record would have provided a better basis for deciding preventability than did review of the study abstract. In particular, a full record review would have provided more opportunity to assess the impact of preexisting medical conditions-conditions most other preventable death studies have neglected.26 Finally panel members included surgeons who cared for some of the patients reviewed, and implicit criteria based on a presumed community standards of care were used. The study would have been stronger if an independent group of surgeons had performed this study, using explicit criteria. It could be argued that because preventable death studies are so subjective, perhaps we should simply replace them with the more objective TRISS method. The present TRISS method, however, has certain limitations that preclude its use in this way. First the proportion of unexpected deaths found to be preventable ranged from 17% among low falls patients to 29% among blunt injury patients (22% overall). Thus the sensitivity of the statistic is too low and the false-positive rate too high for it to be used alone to identify preventable deaths. The false-negative rate is unknown-but presumably is not 0-because preventability was not assessed among expected deaths in the present research. The method also does not account for unexpected saves-those surviving with Ps under 0.5. In the present study, unexpected survivors included 17 patients with penetrating injuries, 21 with blunt injuries, and 5 with low falls. Limitations summarized by Cayten et al."6 also apply to the use of TRISS in identifying preventable deaths. Thus the broad categories of blunt and penetrating used in TRISS calculations result in wide variation in mortality rates within the major subdivisions of each-particularly with regard to differences between patients with gunshot versus stab wounds. The mix of patients in any given study will affect the ratio of expected to unexpected deaths. In addition the RTS has been shown to have virtually no predictive value with respect to the survival of patients with low falls, and the ISS has been found to be quite limited in this regard as well. The facts that 93% of low

519

falls deaths were unexpected in this study and that it was necessary to screen this group for comorbidities supports the suggestion that these patients should be excluded from analyses using the TRISS method. Finally the method is limited in predicting the outcomes of patients with multiple severe injuries to a single body part. For example patients who die of multiple gunshot wounds to the abdomen may well be found to be unexpected deaths using the TRISS method even though the number and severity of their injuries were lethal. Thus the quantitative TRISS method alone cannot measure whether a death actually is preventable. The recently proposed A Severity Characterization of Trauma (ASCOT) method seems promising but has not been independently tested.'4 But using the Ps as audit filter strengthens the conclusions of preventable death studies because it is more difficult for critics to argue that patients in the unexpected death category had such severe injuries that death was inevitable. Conclusions

Analyses of unexpected deaths using the TRISS methodology in an eight-hospital study including trauma and nontrauma centers showed 12% of deaths to be possibly preventable. The incidence of unexpected deaths varied significantly according to mechanism of injury; the incidence of preventable deaths did not differ significantly across groups. Factors in preventable deaths varied by injury cause: delays in operation-most frequent among penetrating and blunt injury patients; management errors-most frequent among blunt and low falls patients; technical errors-most frequent among those with penetrating injunes. Compared with previous studies, there were fewer failures of diagnosis and treatment of abdominal trauma. There remained a problem with early diagnosis and treatment of severe head injury. Problems were identified in the long-term care of post-trauma patients, especially low falls patients, leading to sepsis and multiple organ failure. The advantages and disadvantages of the use of TRISS as an audit filter for preventable deaths are described. Acknowledgments The authors thank the following physicians and their hospitals for participating in this cooperative study: Joseph B. Basile, M.D., Benedictine Hospital; C. Gene Cayten, M.D., M.P.H., Our Lady of Mercy Medical Center; Matthew L. Genovese, M.D., St. Joseph's Medical Center; Kirk K. Kazarian, M.D., The Stamford Hospital; William J. McCann, M.D., New Rochelle Hospital Medical Center; Thomas F. Nealon, Jr., M.D., St. Vincent's Hospital & Medical Center of New York; John A. Savino, M.D., Westchester County Medical Center; William M. Stahl, M.D., Lincoln Medical & Mental Health Center. Appreciation goes to

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Pam Sherman for her preparation of this manuscript. The paper would not have been possible without the tireless professional efforts of Bea Clanton, R.M., Karen Ende, R.N., and Sara Nealon, R.N. The authors thank Dan Byrne, B.A., for establishing and maintaining the information system. Appreciation also goes to Dr. Louis R. Del Guercio for his support of the Institute for Trauma and Emergency Care.

References 1. Cales RH, Trunkey DD. Preventable deaths: a review of trauma care systems development. JAMA 1985; 254(8):1059-1063. 2. Foley RW, Harris LS, Pilcher DB. Abdominal injuries in automobile accidents: review of care of fatally injured patients. J Trauma

1977; 17:611-615. 3. Gertner HR, Baker SP, Rutherford RB, Spitz WU. Evaluation of the management of vehicular fatalities secondary to abdominal injury. J Trauma 1972; 12:425-431. 4. Neuman TS, Bockman MA, Moody P, et al. An autopsy study of traumatic deaths: San Diego County, 1979. Am J Surg 1982; 144:722-727. 5. Shackford SR, MacKersie RC, Davis JW, et al. Epidemiology and pathology of traumatic deaths occurring at a level i trauma center in a regionalized system: the importance ofsecondary brain injury. J Trauma 1989; 29:1392-1397. 6. Cales RH. Trauma mortality in Orange County: the effect of implementation of a regional trauma system. Ann Emerg Med 1984; 13:1:1-9. 7. Fitts WT, Lehr HB, Bitner RL, Spelman JW. An analysis of 950 fatal injuries. Surgery 1964; 56:663-668. 8. Lowe DK, Gately HL, Goss JR, et al. Patterns of death, complication, and error in the management of motor vehicle accident victims: implications for a regional system of trauma care. J Trauma 1983; 23:503-509. 9. West JG, Trunkey DD, Lim RC. Systems of trauma care-a study of two counties. Arch Surg 1979; 114:455-459. 10. Boyd CR, Tolson MA, Copes WS. Evaluating trauma care: the TRISS method. J Trauma 1987; 27:370-378. 11. American Association of Automotive Medicine. The Abbreviated Injury Scale. Arlington Heights, IL, 1985. 12. Champion HR, Sacco WJ, Copes WS, et al. A revision of the trauma score. J Trauma 1989; 29:623-629.

DISCUSSION DR. ALEXANDER WALT (Detroit, Michigan): I think this is a very well-motivated paper but certainly not an easy one. The thesis advanced merits careful study because it attempts to apply objectivity to clinical impression, for what I sometimes call the Will-of-God syndrome. To do this the authors have created a very sophisticated statistical sieve through which they hope to capture ostensibly preventable adverse events. The Committee on Trauma of the American College of Surgeons has been an exemplary force in the exercise of stringent self-criticism over

the years and in designing strict but attainable standards of practice for the treatment of injured patients. What Dr. Cayten and his group have done, as I see it, is to incorporate the Committee on Trauma's methods and to extend them. Anytime a surgeon sees a patient, four questions are asked. Is the operation needed at all? How soon does it need to be done? What should be done at the operation? How do we obviate long-term adverse sequelae? These are the questions that this study has been dealing with but I have a few problems with it. Firstly there are some heartening results in that there were very few technical errors, and their conclusion is that in this study at least they no longer made the same sort of errors that they used to make. For example they identified no missed ruptures of the spleen. But a caveat-the numbers are very small. The second comment is that delays in operating are not clearly defined. The delays seem not to have occurred in abdominal nor in thoracic

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13. Gennarelli TA, Champion HR, Sacco WJ, et al. Mortality of patients with head injury and extracranial injury treated in trauma centers: J Trauma 1989; 29:1193-1202. 14. Champion HR, Copes WS, Sacco WJ, et al. A new characterization of injury severity. J Trauma 1990; 30(5):539-546. 15. MacKenzie EJ, Shapiro S, Eastham JN. The abbreviated injury scale and injury severity score. Medical Care 1985; 23:6. 16. Cayten CG, Stahl WM, Murphy JG, et al. Limitations ofthe TRISS method for interhospital comparisons: a multihospital study. J Trauma April 1991; 31:471-482. 17. Certo TF, Robers FB, Pilcher DB. Review of care of fatally injured patients in a rural state: 5-year followup. J Trauma 1983; 23: 559-565. 18. Kreis D, Plascencia G, Augenstein D, et al. Preventable trauma deaths: Dade County, Florida. J Trauma 1986; 26:649-654. 19. Campbell S, Watkins G, Kreis D. Preventable deaths in a self-designated trauma system. The American Surgeon 1989; 478-480. 20. Moylan JA, Detmer DE, Rose J, Schulz R. Evaluation of the quality of hospital care for major trauma. J Trauma 1976; 16:517-523. 21. West JG, Yurko AA. An Autopsy method for evaluating trauma care. J Trauma 1981; 21:32-34. 22. Committee on Trauma of the American College of Surgeons. Quality assurance in trauma care: appendix G to hospital resources document. Bulletin American College of Surgeons 1987; 72:2:4247. 23. Shackford SR, Hollingsworth-Fridlund P, McArdle M, Eastman AB. Assuring quality in a trauma system-the medical audit committee: composition, cost and results. J Trauma 1987; 27:866-875. 24. Detmer DE, Moylan JA, Rose J, et al. Regional categorization and quality of care in major trauma. J Trauma 1977; 17:592-599. 25. Van Wagoner FH. Died in hospital. a three year study of deaths following trauma. Read before the Twentieth Annual Session of The American Association for the Surgery of Trauma, Coronado, California, October 5-7, 1960. 26. Spain DM, Fox RI, Marcus A. Evaluation of hospital care in one trauma care system. Am J Public Health 1984; 74(10):1122-

1125. 27. Morris JA Jr, MacKenzie EJ, Edelstein SL. The effect of preexisting conditions on mortality in trauma patients. JAMA 1990; 263(14): 1942-1946. 28. Morris JA Jr, MacKenzie EJ, Damiano AM, Bass SM. Mortality in trauma patients: the interaction between host factors and severity. J Trauma 1990; 30:1476-1482. injuries, but seem to be confined to head injuries. It appears therefore that they still have a big problem in the head injury field, which we know to be a national weakness. The third group that bothers me-and it is a large group-is labeled "errors in management." I think that you have been rather harsh in your judgment of what constitutes an error in management; for example, in the so-called low-fall group, the vast majority of the patients were 70 and 80 years of age. I will quote from the paper where you state: "The errors involve the inability to prevent and effectively treat complications such as pneumonia, pulmonary embolism, organ system failure in patients that should have recovered from their injuries." This is a vague sort of statement. You are suggesting that unless we prevent pulmonary embolism, unless we prevent pneumonia, unless we prevent organ system failure, we are in error. I think I take issue with this gloomy assessment, regarding it more as an exercise in masochism and self-flagellation. Some bothersome questions lead from this attitude. If we set an inappropriately high standard, as I think that you have done, might we not then be held unfairly to that unattainable standard? I think that in your zeal to interpret your figures so critically, you have really set yourself, and therefore us, goals that are impossible to reach. Some of your adverse outcomes are often not errors in management as far as I am concerned. Three questions as I close. How do you propose to translate the findings of this very intricate study into clinical practice? How do we reduce the so-called errors in management? Is the cost of this effort such that we should have this methodology applied on a national level, and is it feasible to do so?

Analyses of preventable deaths by mechanism of injury among 13,500 trauma admissions.

Preventable deaths (PD) were evaluated by mechanism of injury for 13,500 trauma admissions to eight hospitals over 2 years. There were 42 (3.3%) hospi...
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