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The revised cardiac risk index is associated with morbidity and mortality independent of injury severity in elderly patients with rib fractures

  • Gary Alan Bass
    Affiliations
    Division of Traumatology, Surgical Critical Care and Emergency Surgery, Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA

    School of Medical Sciences, Orebro University, Orebro, Sweden

    Leonard Davis Institute of Health Economics (LDI), University of Pennsylvania, Philadelphia, USA

    Center for Peri-Operative Outcomes Research and Transformation (CPORT), University of Pennsylvania, Philadelphia, USA
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  • Caoimhe C Duffy
    Affiliations
    Leonard Davis Institute of Health Economics (LDI), University of Pennsylvania, Philadelphia, USA

    Center for Peri-Operative Outcomes Research and Transformation (CPORT), University of Pennsylvania, Philadelphia, USA
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  • Lewis J Kaplan
    Affiliations
    Division of Traumatology, Surgical Critical Care and Emergency Surgery, Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA

    Department of Anesthesia and Critical Care, University of Pennsylvania, Philadelphia, USA

    Corporal Michael Cresenscz Veterans Affairs Medical Center (CMCVAMC), Philadelphia, USA
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  • Babak Sarani
    Affiliations
    Center for Trauma and Critical Care, George Washington University School of Medicine & Health Sciences, Washington D.C., USA
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  • Niels D Martin
    Affiliations
    Division of Traumatology, Surgical Critical Care and Emergency Surgery, Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
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  • Ahmad Mohammad Ismail
    Affiliations
    School of Medical Sciences, Orebro University, Orebro, Sweden
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  • Yang Cao
    Affiliations
    Clinical Epidemiology and Biostatistics, School of Medical Sciences, Orebro University, Orebro, Sweden
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  • Maximilian Peter Forssten
    Affiliations
    School of Medical Sciences, Orebro University, Orebro, Sweden
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  • Shahin Mohseni
    Correspondence
    Corresponding author at: Orebro University Hospital, 701 85 Orebro, Sweden, School of Medical Sciences, Orebro University, 702 81 Orebro, Sweden
    Affiliations
    School of Medical Sciences, Orebro University, Orebro, Sweden

    Division of Trauma & Emergency Surgery, Department of Surgery, Orebro University Hospital, Orebro, Sweden
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Open AccessPublished:November 12, 2022DOI:https://doi.org/10.1016/j.injury.2022.11.039

      Abstract

      Background

      Risk factors for mortality and in-hospital morbidity among geriatric patients with traumatic rib fractures remain unclear. Such patients are often frail and demonstrate a high comorbidity burden. Moreover, outcomes anticipated by current rubrics may reflect the influence of multisystem injury or surgery, and thus not apply to isolated injuries in geriatric patients. We hypothesized that the Revised Cardiac Risk Index (RCRI) may assist in risk-stratifying geriatric patients following rib fracture.

      Methods

      All geriatric patients (age ≥65 years) with a conservatively managed rib fracture owing to an isolated thoracic injury (thorax AIS ≥1), in the 2013-2019 TQIP database were assessed including demographics and outcomes. The association between the RCRI and in-hospital morbidity as well as mortality was analyzed using Poisson regression models while adjusting for potential confounders.

      Results

      96,750 geriatric patients sustained rib fractures. Compared to those with RCRI 0, patients with an RCRI score of 1 had a 16% increased risk of in-hospital mortality [adjusted incidence rate ratio (adj-IRR), 95% confidence interval (CI): 1.16 (1.02-1.32), p=0.020]. An RCRI score of 2 [adj-IRR (95% CI): 1.72 (1.44-2.06), p<0.001] or ≥3 [adj-IRR (95% CI): 3.07 (2.31-4.09), p<0.001] was associated with an even greater mortality risk. Those with an increased RCRI also exhibited a higher incidence of myocardial infarction, cardiac arrest, stroke, and acute respiratory distress syndrome.

      Conclusions

      Geriatric patients with rib fractures and an RCRI ≥1 represent a vulnerable and high-risk group. This index may inform the decision to admit for inpatient care and can also guide patient and family counseling as well as computer-based decision-support.

      Keywords

      Background

      Damage to the thoracic cage and its contents is common in the injured patient and often drives care in a critical care setting.[
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      Bulger EM. Geriatric Trauma and Critical Care. 2017; 285–290.

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      ] Elderly patients, who are often frail and demonstrate a high comorbidity burden, are at higher risk of developing complications and are less likely to regain their baseline function due to diminished physiologic reserve. Relatedly, a Delphi Consensus Survey conducted by the National Trauma Research Action Plan, identified geriatric rib fracture management within the top three prioritized areas of Geriatric Traumatology.[
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      ]
      The Revised Cardiac Risk Index (RCRI) was initially developed to predict 30-day postoperative myocardial infarction, cardiac arrest, or mortality following noncardiac surgery [
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      ] isolated severe traumatic brain injury,[
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      Mortality risk stratification in isolated severe traumatic brain injury using the revised cardiac risk index.
      ] as well as in traumatic hip fracture patients,[
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      ] the latter serving as a population that also suffers from frailty and a high comorbidity burden. The RCRI has not been assessed as a stratification tool following rib fracture but may reflect the aggregated impact of multimorbidity in a reliable fashion. We hypothesized that the RCRI accurately risk-stratifies geriatric patient mortality after traumatic rib fracture without concomitant injuries.

      Methods

      All variables were retrieved from the Trauma Quality Improvement Program (TQIP) dataset. These included outcomes such as length of stay, in-hospital mortality and complications, as well as demographic data regarding patient age, sex, race, presence of flail chest and other thoracic injuries, the highest thorax Abbreviated Injury Score (AIS), surgical interventions, and comorbidities. All geriatric patients (65 years or older) registered in the TQIP database between 2013 and 2019 who suffered one or more rib fractures owing to an isolated thoracic injury (thorax AIS ≥1 with an AIS ≤1 in all other regions), that were managed conservatively (i.e. non-operatively), were included. All patients who underwent thoracic surgery (including rib fracture fixation) were excluded. Since an AIS score of 6 is usually not considered survivable, patients with a thorax AIS of 6 were also excluded. The need for approval by the institutional review board was waived for this study since it only made use of aggregated anonymized retrospective data. All aspects of the study complied with both the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines and Declaration of Helsinki.

      Calculation of the RCRI

      The RCRI uses six independent and routinely acquired variables: high-risk surgery (any intraperitoneal, intrathoracic, and supra-inguinal vascular procedure), history of cerebrovascular disease, renal insufficiency (defined as acute kidney injury or chronic kidney disease), diabetes mellitus, ischemic heart disease, as well as congestive heart failure (Figure 1).[
      • Bass GA
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      • Hulme RA
      • Cao Y
      • Matthiessen P
      • et al.
      Cardiac risk stratification in emergency resection for colonic tumours.
      ,
      • Forssten MP
      • Bass GA
      • Scheufler K-M
      • Ismail AM
      • Cao Y
      • Martin ND
      • et al.
      Mortality risk stratification in isolated severe traumatic brain injury using the revised cardiac risk index.
      ,
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      Perioperative beta-blocker therapy and mortality after major noncardiac surgery.
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      2014 ACC/AHA guideline on perioperative cardiovascular evaluation and management of patients undergoing noncardiac surgery.
      ,
      • Hulme RA
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      • et al.
      The association between revised cardiac risk index and postoperative mortality following elective colon cancer surgery: a retrospective nationwide cohort study.
      ] Each patient received one point for each variable present. Since this cohort consisted of patients with conservatively managed rib fractures, no patients were included that underwent high-risk surgery; accordingly, the maximum possible score was 5.
      Fig 1
      Fig. 1The Revised Cardiac Risk Index, after Lindenauer et al.
      [
      • Lindenauer PK
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      • Wang K
      • Mamidi DK
      • Gutierrez B
      • Benjamin EM.
      Perioperative beta-blocker therapy and mortality after major noncardiac surgery.
      ]

      Statistical analysis

      Patients were sorted into 4 groups based on their RCRI score: RCRI 0, RCRI 1, RCRI 2, RCRI ≥3. Demographics and other clinical features pertaining to the patients were aggregated and compared to highlight differences between the groups. Categorical variables were presented as counts along with percentages. Continuous variables were summarized using a median and interquartile range (IQR) since they were non-normally distributed. For the categorical variables, the Chi-square test or Fisher's exact test was used to calculate the statistical significance of differences between the groups, while the Kruskal-Wallis test was applied to continuous variables. The primary outcome of interest was in-hospital mortality. Secondary outcomes consisted of complications recorded in TQIP; these included myocardial infarction, cardiac arrest with CPR, stroke, and acute respiratory distress syndrome (ARDS).
      The association between in-hospital mortality and the RCRI was analyzed using a Poisson regression model with robust standard errors. Adjustments were made for age, sex, race, the presence of a flail chest, sternal fracture, pneumothorax, hemothorax, or pulmonary contusion as well as comorbidities. The comorbidities included were hypertension, peripheral vascular disease, dementia, chronic obstructive pulmonary disease, smoking status, liver cirrhosis, drug use disorder, alcohol use disorder, major psychiatric illnesses, coagulopathy, cancer receiving chemotherapy, and metastatic cancer. This analysis was repeated with each of the previously listed complications replacing in-hospital mortality as the outcome. The associations estimated by the models were presented as incident rate ratios (IRRs) and 95% confidence intervals (CIs).
      Further, a subgroup analysis was also performed on patients with isolated rib fractures, in which the former analyses were repeated. Isolated rib fracture(s) was defined as the presence of a rib fracture without any intrathoracic injury (pneumothorax, hemothorax, or pulmonary contusion).
      Multiple imputation by chained equations was used to manage missing values. Statistical significance was defined as a two-sided p-value <0.05. Analyses were performed using the statistical software R 4.1.1 (R Foundation for Statistical Computing, Vienna, Austria. http://www.R-project.org/).
      Table 1Patient demographics and clinical features in geriatric patients with conservatively managed rib fractures
      RCRI 0 (N = 61,442)RCRI 1 (N = 27,872)RCRI 2 (N = 6,241)RCRI ≥3 (N = 1,195)P-value
      Age, median [IQR]77 [70-83]77 [71-83]77 [72-83]77 [71-83]<0.001
      Sex, n (%)<0.001
      Female29,557 (48.1)12,101 (43.4)2,588 (41.5)451 (37.7)
      Male31,870 (51.9)15,765 (56.6)3,653 (58.5)744 (62.3)
      Missing15 (0.0)6 (0.0)0 (0.0)0 (0.0)
      White, n (%)54,460 (88.6)23,799 (85.4)5,269 (84.4)976 (81.7)<0.001
      Black, n (%)2,596 (4.2)1,549 (5.6)395 (6.3)124 (10.4)<0.001
      Asian, n (%)1,182 (1.9)676 (2.4)146 (2.3)19 (1.6)<0.001
      American Indian, n (%)171 (0.3)110 (0.4)34 (0.5)7 (0.6)<0.001
      Pacific islander, n (%)76 (0.1)54 (0.2)21 (0.3)7 (0.6)<0.001
      Other, n (%)2,132 (3.5)1,319 (4.7)318 (5.1)55 (4.6)<0.001
      Missing512 (0.8)214 (0.8)33 (0.5)5 (0.4)
      Thorax AIS, n (%)<0.001
      16,223 (10.1)3,157 (11.3)830 (13.3)169 (14.1)
      215,442 (25.1)6,929 (24.9)1,531 (24.5)314 (26.3)
      338,284 (62.3)17,255 (61.9)3,771 (60.4)704 (58.9)
      41,206 (2.0)462 (1.7)98 (1.6)8 (0.7)
      5287 (0.5)69 (0.2)11 (0.2)0 (0.0)
      Flail chest, n (%)1,385 (2.3)578 (2.1)136 (2.2)10 (0.8)0.004
      Sternal fracture, n (%)4,294 (7.0)1,539 (5.5)221 (3.5)25 (2.1)<0.001
      Pneumothorax, n (%)15,264 (24.8)5,053 (18.1)898 (14.4)131 (11.0)<0.001
      Hemothorax, n (%)7,585 (12.3)3,079 (11.0)691 (11.1)125 (10.5)<0.001
      Pulmonary contusion, n (%)5,586 (9.1)2,217 (8.0)486 (7.8)88 (7.4)<0.001
      RCRI, Revised Cardiac Risk Index; IQR, Interquartile Range; AIS, Abbreviated Injury Score

      Results

      The study population consisted of 96,750 conservatively managed rib fracture patients. Patients with a high RCRI score were less often white [RCRI ≥3: 81.7% vs RCRI 0: 88.6%, p <0.001] and more often male [RCRI ≥3: 62.3% vs RCRI 0: 51.9%, p <0.001], but there was no clinically significant difference in the median age of the patients. Most comorbidities increased in prevalence at higher RCRI scores, with the exceptions being substance use disorders and patients receiving chemotherapy for cancer (Table 2). Patients with a higher RCRI also generally required a slightly longer hospital stay [RCRI ≥3: 5 days vs RCRI 0: 4 days, p <0.001]. Moreover, crude in-hospital mortality increased progressively for each additional point on the RCRI [RCRI ≥3: 6.0% vs RCRI 0: 1.8%, p <0.001]. The same trend was observed in the crude rates of myocardial infarction, cardiac arrest with CPR, stroke, and ARDS, which all increased along with the RCRI score (Table 3).
      Table 2Comorbidities in geriatric patients with conservatively managed rib fractures
      RCRI 0 (N = 61,442)RCRI 1 (N = 27,872)RCRI 2 (N = 6,241)RCRI ≥3 (N = 1,195)P-value
      Hypertension, n (%)35,084 (57.1)21,490 (77.1)4,990 (80.0)957 (80.1)<0.001
      Myocardial infarction, n (%)0 (0.0)862 (3.1)755 (12.1)379 (31.7)<0.001
      Congestive heart failure, n (%)0 (0.0)4,296 (15.4)3,282 (52.6)959 (80.3)<0.001
      Peripheral vascular disease, n (%)618 (1.0)609 (2.2)243 (3.9)83 (6.9)<0.001
      Cerebrovascular disease, n (%)0 (0.0)2,676 (9.6)1,812 (29.0)534 (44.7)<0.001
      Dementia, n (%)5,896 (9.6)2,830 (10.2)676 (10.8)124 (10.4)0.002
      COPD, n (%)8,752 (14.2)5,059 (18.2)1,619 (25.9)349 (29.2)<0.001
      Current smoker, n (%)6,392 (10.4)2,488 (8.9)556 (8.9)94 (7.9)<0.001
      Liver cirrhosis, n (%)469 (0.8)426 (1.5)122 (2.0)24 (2.0)<0.001
      Drug use disorder, n (%)930 (1.5)380 (1.4)84 (1.3)13 (1.1)0.191
      Alcohol use disorder, n (%)2,896 (4.7)873 (3.1)167 (2.7)22 (1.8)<0.001
      Major psychiatric illness, n (%)6,495 (10.6)3,207 (11.5)812 (13.0)167 (14.0)<0.001
      Diabetes mellitus, n (%)0 (0.0)18,785 (67.4)5,144 (82.4)1,103 (92.3)<0.001
      Coagulopathy, n (%)3,794 (6.2)2,765 (9.9)876 (14.0)162 (13.6)<0.001
      Chronic kidney disease, n (%)0 (0.0)949 (3.4)1,215 (19.5)619 (51.8)<0.001
      Acute kidney injury, n (%)0 (0.0)205 (0.7)194 (3.1)81 (6.8)<0.001
      Currently receiving chemotherapy for cancer, n (%)485 (0.8)209 (0.7)35 (0.6)5 (0.4)0.118
      Metastatic cancer, n (%)781 (1.3)364 (1.3)105 (1.7)21 (1.8)0.026
      RCRI, Revised Cardiac Risk Index; COPD, Chronic Obstructive Pulmonary Disease
      Table 3Crude outcomes in geriatric patients with conservatively managed rib fractures
      RCRI 0 (N = 61,442)RCRI 1 (N = 27,872)RCRI 2 (N = 6,241)RCRI ≥3 (N = 1,195)P-value
      Length of stay, median [IQR]4.0 [2.0-6.0]4.0 [3.0-6.0]5.0 [3.0-8.0]5.0 [3.0-9.0]<0.001
      Missing, n (%)602 (1.0)240 (0.9)66 (1.1)13 (1.1)
      In-hospital mortality, n (%)1,078 (1.8)582 (2.1)224 (3.6)72 (6.0)<0.001
      Missing4 (0.0)0 (0.0)0 (0.0)0 (0.0)
      Myocardial infarction, n (%)74 (0.1)63 (0.2)22 (0.4)7 (0.6)<0.001
      Cardiac arrest with CPR, n (%)175 (0.3)115 (0.4)43 (0.7)25 (2.1)<0.001
      Stroke, n (%)64 (0.1)51 (0.2)19 (0.3)4 (0.3)<0.001
      ARDS, n (%)87 (0.1)73 (0.3)25 (0.4)8 (0.7)<0.001
      RCRI, Revised Cardiac Risk Index; ARDS, Acute Respiratory Distress Syndrome
      After adjusting for the previously mentioned covariates, the risk of in-hospital mortality consistently increased with higher RCRI scores. Compared to RCRI 0, patients with RCRI 1 had a 16% higher risk of in-hospital mortality [adjusted IRR 1.16, 95% CI 1.02-1.32, p = 0.20], while patients with RCRI ≥3 exhibited a 207% higher risk of in-hospital mortality [adjusted IRR 3.07, 95% CI 2.31-4.09, p <0.001]. Relatedly, the risk of complications also increased at higher RCRI scores. A patient with RCRI ≥3 had a 4 times higher risk of myocardial infarction [adjusted IRR 4.15, 95% CI 1.29-13.34, p = 0.017], an 11 times higher risk of cardiac arrest with CPR [adjusted IRR 10.81, 95% CI 6.48-18.03, p <0.001], and a 6 times higher risk of ARDS [adjusted IRR 5.59, 95% CI 2.30-13.57, p <0.001], compared to those with RCRI 0. A statistically significant increased risk of stroke was only detected for patients with RCRI 1 [adjusted IRR 5.30, 95% CI 1.90-14.82, p = 0.002] and RCRI 2 [adjusted IRR 9.85, 95% CI 3.14-30.94, p <0.001] (Table 4).
      Table 4Incident rate ratios for adverse outcomes based on the RCRI score in geriatric patients with conservatively managed rib fractures
      OutcomeRCRI 0RCRI 1 IRR (95% CI)P-valueRCRI 2 IRR (95% CI)P-valueRCRI ≥3 IRR (95% CI)P-value
      In-hospital mortalityReference1.16 (1.02-1.32)0.0201.72 (1.44-2.06)<0.0013.07 (2.31-4.09)<0.001
      Myocardial infarctionReference1.78 (1.07-2.96)0.0274.42 (2.44-8.01)<0.0014.15 (1.29-13.34)0.017
      Cardiac arrest with CPRReference1.66 (1.18-2.35)0.0042.76 (1.71-4.45)<0.00110.81 (6.48-18.03)<0.001
      ARDSReference1.81 (1.16-2.82)0.0092.62 (1.40-4.92)0.0035.59 (2.30-13.57)<0.001
      IRRs are calculated using Poisson regression models with robust standard errors. Missing values were managed using multiple imputation by chained equations. Analyses were adjusted for age, sex, race, highest abbreviated injury score in each region, the presence of a flail chest, sternal fracture, pneumothorax, hemothorax, or pulmonary contusion as well as hypertension, peripheral vascular disease, dementia, chronic obstructive pulmonary disease, smoking status, liver cirrhosis, drug use disorder, alcohol use disorder, major psychiatric illnesses, coagulopathy, cancer receiving chemotherapy, metastatic cancer, and advanced directives limiting care.
      RCRI, Revised Cardiac Risk Index; IRR, Incident Rate Ratio; CI, Confidence Interval; ARDS, Acute Respiratory Distress Syndrome
      A total of 65,375 did not have any intrathoracic injury, i.e. constituted the isolated rib fracture cohort. In this subgroup the analyses detected that an RCRI score ≥2 remained associated with an increased risk of in-hospital mortality (RCRI 2: adj-IRR 1.71, p <0.001; RCRI ≥3: adj-IRR 3.18, p <0.001). There was also an increased risk for in-hospital risk of myocardial infarction (RCRI 2: adj-IRR 6.86, p <0.001; RCRI ≥3: adj-IRR 8.81, p = 0.005) and cardiac arrest with CPR (RCRI 2: adj-IRR 3.53, p <0.001; RCRI ≥3: adj-IRR 12.74, p <0.001). Isolated rib fracture patients with an RCRI score ≥3 also exhibited an excess risk of significantly higher risk of developing ARDS (RCRI ≥3: adj-IRR 8.04, p = 0.003) (Table 5).
      Table 5Incident rate ratios for adverse outcomes based on the RCRI score in geriatric patients with conservatively managed, isolated rib fractures (N=65,375)
      OutcomeRCRI 0RCRI 1 IRR (95% CI)P-valueRCRI 2 IRR (95% CI)P-valueRCRI ≥3 IRR (95% CI)P-value
      In-hospital mortalityReference1.11 (0.92-1.33)0.2661.71 (1.33-2.20)<0.0013.18 (2.21-4.60)<0.001
      Myocardial infarctionReference2.15 (0.86-5.38)0.1036.86 (2.65-17.81)<0.0018.81 (1.94-40.02)0.005
      Cardiac arrest with CPRReference1.07 (0.55-2.09)0.8433.53 (1.77-7.05)<0.00112.74 (6.27-25.90)<0.001
      ARDSReference1.81 (0.71-4.58)0.2143.02 (0.97-9.39)0.0568.04 (2.06-31.31)0.003
      An isolated rib fracture is defined as the presence of a rib fracture without any intrathoracic injuries. IRRs are calculated using Poisson regression models with robust standard errors. Missing values were managed using multiple imputation by chained equations. Analyses were adjusted for age, sex, race, highest abbreviated injury score in each region, the presence of a flail chest, sternal fracture, as well as hypertension, peripheral vascular disease, dementia, chronic obstructive pulmonary disease, smoking status, liver cirrhosis, drug use disorder, alcohol use disorder, major psychiatric illnesses, coagulopathy, cancer receiving chemotherapy, metastatic cancer, and advanced directives limiting care.
      RCRI, Revised Cardiac Risk Index; IRR, Incident Rate Ratio; CI, Confidence Interval; ARDS, Acute Respiratory Distress Syndrome

      Discussion

      Outcome assessments for surgical patients occur in the elective pre-operative setting, the urgent or emergency setting, and after injury with or without the need for operative or procedural intervention. Both the American College of Surgeons National Surgical Quality Improvement Program and the Veteran's Affairs Surgical Quality Improvement Program offer morbidity and mortality calculators to assess patient risk for specific outcomes. [
      • Lubitz AL
      • Chan E
      • Zarif D
      • Ross H
      • Philp M
      • Goldberg AJ
      • et al.
      American college of surgeons nsqip risk calculator accuracy for emergent and elective colorectal operations.
      ,
      • Rozeboom PD
      • Bronsert MR
      • Velopulos CG
      • Henderson WG
      • Colborn KL
      • Hammermeister KE
      • et al.
      A comparison of the new, parsimonious tool Surgical Risk Preoperative Assessment System (SURPAS) to the American College of Surgeons (ACS) risk calculator in emergency surgery.
      ,
      • Imran JB
      • Renteria O
      • Ruiz M
      • Pham TH
      • Mokdad AA
      • Huerta S.
      Assessing the veterans affairs surgical quality improvement program risk calculator in cholecystectomy.
      ] However, these assessment tools were developed principally for elective procedures and may not adequately reflect the risk that injured patients may bear. Following injury, the Trauma Quality Improvement Program offers a similar assessment tool that has been built using aggregate and robust data leveraging preexisting assessors of outcomes such as the Trauma Score (TS), the Revised Trauma Score (RTS), the Trauma and Injury Severity Score (TRISS), and the New Injury Severity Score (NISS) tools. [
      • Dhillon TS
      • Galante JM
      • Salcedo ES
      • Utter GH.
      Characteristics of chest wall injuries that predict postrecovery pulmonary symptoms.
      ,
      • Chapman BC
      • Herbert B
      • Rodil M
      • Salotto J
      • Stovall RT
      • Biffl W
      • et al.
      RibScore.
      ,
      • Hardin KS
      • Leasia KN
      • Haenel J
      • Moore EE
      • Burlew CC
      • Pieracci FM.
      The sequential clinical assessment of respiratory function (SCARF) score: a dynamic pulmonary physiologic score that predicts adverse outcomes in critically ill rib fracture patients.
      ,
      • Samman Y
      • Masood I
      • Killampalli VV
      • Howell N
      • Alpar EK
      • Banerjee SK.
      The value of lung injury score in assessing the outcome of patients with rib fracture.
      ,
      • Seok J
      • Cho HM
      • Kim HH
      • Kim JH
      • Huh U
      • Kim HB
      • et al.
      Chest trauma scoring systems for predicting respiratory complications in isolated rib fracture.
      ] The performance fidelity of these tools is less than ideal for patients with single system injury, but they may perform better with multiple injuries and higher ISS. Furthermore, advanced age and the interplay of comorbidities may also degrade accurate prediction in the elderly.
      Unsurprisingly, and especially for the elderly, other tools have surfaced for use in elective surgery risk prediction including those that incorporate frailty into their metrics. Assessment tools for morbidity and mortality risk after elective surgery are well embedded in pre-operative evaluations and include age, the American Society of Anesthesiologists physical status classification, as well as a host of scoring systems including, but not limited to, that of NSQIP or VASQIP, P-POSSUM, E-PASS, SURPASS, NELA risk calculator, Charlson Comorbidity Index, and the machine learning-based POTTER score.[
      • Lubitz AL
      • Chan E
      • Zarif D
      • Ross H
      • Philp M
      • Goldberg AJ
      • et al.
      American college of surgeons nsqip risk calculator accuracy for emergent and elective colorectal operations.
      ,
      • Rozeboom PD
      • Bronsert MR
      • Velopulos CG
      • Henderson WG
      • Colborn KL
      • Hammermeister KE
      • et al.
      A comparison of the new, parsimonious tool Surgical Risk Preoperative Assessment System (SURPAS) to the American College of Surgeons (ACS) risk calculator in emergency surgery.
      ,
      • Imran JB
      • Renteria O
      • Ruiz M
      • Pham TH
      • Mokdad AA
      • Huerta S.
      Assessing the veterans affairs surgical quality improvement program risk calculator in cholecystectomy.
      ,
      • St-Louis E
      • Iqbal S
      • Feldman LS
      • Sudarshan M
      • Deckelbaum DL
      • Razek TS
      • et al.
      Using the age-adjusted Charlson comorbidity index to predict outcomes in emergency general surgery.
      ,
      • Cao Y
      • Bass GA
      • Ahl R
      • Pourlotfi A
      • Geijer H
      • Montgomery S
      • et al.
      The statistical importance of P-POSSUM scores for predicting mortality after emergency laparotomy in geriatric patients.
      ] Additional more tightly focused scoring systems explore the risk of post-operative pneumonia, or surgical site infection. Cardiac risk assessment for non-cardiac surgery is indelibly tied to the Goldman score and its revision as the Lee-Goldman score two decades later.[
      • Azevedo PS
      • Gumieiro DN
      • Polegato BF
      • Pereira GJC
      • Silva IA
      • Pio SM
      • et al.
      Goldman score, but not Detsky or Lee indices, predicts mortality 6 months after hip fracture.
      ] Indeed, a detailed assessment of cardiac risk is essential as a high-risk profile should inform specific pre-operative evaluations to determine if risk reduction is possible. Patients with urgent or emergent conditions can seldom pursue such evaluations and may instead undergo more invasive monitoring to detect adverse events. Shifts in patient comorbidities may not reflect the same profiles that generated older risk assessment models.
      Cardiac ultrasound has advanced our understanding of the interplay of structural and functional abnormalities defining entities such as hypertrophic obstructive cardiomyopathy (HOCM) and Takotsubo cardiomyopathy among others. Vastly improved knowledge of the right ventricle (RV) shifted management from using the RV as a “pass through” mechanism to a chamber that benefits from ionotropic support, and increasingly mechanical support techniques, especially in conjunction with left ventricular failure. [
      • Woulfe KC
      • Walker LA.
      Physiology of the right ventricle across the lifespan.
      ] Heart failure is now assessed based on the degree of ejection fraction (EF) preservation. As physiology was revealed, new therapeutics blossomed including afterload reducing agents, minimally invasive approaches to valve repair, and implanted devices for rhythm control or rescue. Extracorporeal techniques as rescue therapy or a bridge to organ transplantation are commonplace. So too are undesirable sequelae of non-cardiac therapeutics such as chemotherapy-impaired EF. In contrast, tobacco use (at least in the US) is decreasing, as are occupational exposures.[
      • Sakinah S
      • Nugroho SD.
      Relationship between smoking and ischemic stroke: meta analysis.
      ,
      • Osibogun O
      • Bursac Z
      • Maziak W.
      Longitudinal transition outcomes among adult dual users of e-cigarettes and cigarettes with the intention to quit in the United States: PATH Study (2013–2018).
      ] Improved glycemic control relies on a host of approaches such as insulin pumps, novel agents, and pancreas transplantation. Many of these elements were not present, or were much less accessible, when older risk models were being developed. Accordingly, cardiac risk tools merited revision.
      The RCRI represents one such revision of cardiac risk assessment tools. It is optimally modified to be readily deployable at the bedside without the need for advanced machine learning or artificial intelligence support. The RCRI interweaves the cardiac system and related systems that impact cardiac function. How well the RCRI performs after injury remains opaque. It is therefore most ideal to assess RCRI performance within the context of single system injury. Such a focused approach reduces confounding from other injuries. Certainly, the high-risk group for adverse outcomes driven by cardiac risk are the elderly with less reserve to traumatic stress– the focus of this study.
      Our data show an escalating association between multimorbidity (as estimated by RCRI) and post-injury complications as well as mortality, following isolated traumatic rib fractures with and without concomitant intrathoracic organ injury in the elderly patient. When AIS Chest grade is accounted for in regression models, this association appears to persist. The risk of death, cardiac adverse events, and ARDS all increase linearly with increasing RCRI in the current study. Therefore, our data support using the RCRI as a risk stratifying tool in the elderly with rib fractures. How well the RCRI will perform after multi-system injury, or the need for emergency operation for thoracic injuries remains to be studied.
      Since the elderly represent an increasing proportion of injured patients presenting to US trauma centers, having a reliable way to assess their risk is warranted. Predominant mechanisms of injury in this group include falls, auto-pedestrian impact, and motor vehicle collisions with blunt assault occurring much less frequently. The elderly are much less impacted by the increase in firearm violence that has permeated the US in concert with the pandemic and public health measures.[
      • Abdallah HO
      • Zhao C
      • Kaufman E
      • Hatchimonji J
      • Swendiman RA
      • Kaplan LJ
      • et al.
      Increased firearm injury during the COVID-19 pandemic: a hidden urban burden.
      ] This study demonstrates that, at least for elderly patients sustaining rib fractures, their in-hospital risk profile is accurately represented by the RCRI. Other metrics such as the PIC score drive the location of inpatient care and may dovetail with the RCRI to assess the need for admission.[
      • Bass GA
      • Stephen C
      • Forssten MP
      • Bailey JA
      • Mohseni S
      • Cao Y
      • et al.
      Admission triage with pain, inspiratory effort, cough score can predict critical care utilization and length of stay in isolated chest wall injury.
      ] While the RCRI will assess likely trajectories, some courses may be strongly influenced by the adequacy and the method of analgesia. For instance, an opioid rich analgesic routine may lead to acute respiratory depression while one that principally relies on non-opioid multi-modal analgesia avoids such risks. Neither of these treatment approaches are captured in post-injury risk assessment tools. Moreover, newer methods of analgesia such as cryoablation may substantially influence outcomes by supporting excellent pulmonary hygiene by eliminating rib fracture associated pain.[
      • Wu CL
      • Jani ND
      • Perkins FM
      • Barquist E.
      Thoracic epidural analgesia versus intravenous patient-controlled analgesia for the treatment of rib fracture pain after motor vehicle crash.
      ,
      • Klesius L
      • Schroeder K.
      Effective analgesia with bilateral erector spinae plane catheters for a patient with traumatic rib and spine fractures.
      ,
      • Coary R
      • Skerritt C
      • Carey A
      • Rudd S
      • Shipway D.
      New horizons in rib fracture management in the older adult.
      ] Since the RCRI rapidly and strongly identifies discrete risk profiles in the geriatric trauma patient, it seems suitable for incorporation into electronic health records to provide computer aided decision support.
      Important limitations that impact the results of our study flow from its retrospective assessment of an administrative dataset. Therefore, the results should be interpreted as associative and hypothesis generating rather than definitive. The interaction between number of rib fractures and outcomes is mired in controversy. While some studies have demonstrated a positive association between the number of rib fractures and patient outcomes, others have failed to do so, focusing more on derangements of ventilatory mechanics associated with an unstable chest wall and underlying pulmonary contusion. The inquiry focus in this manuscript was on the multimorbidity burden, as assessed by risk stratification tools such as RCRI. Acknowledging that to cross-tabulate the cohort by number of rib fractures would substantially increase the complexity of the statistical analysis, while decreasing its power and clinical utility, we instead used the Abbreviated Injury Scale and the presence of flail chest, as well other underlying injuries (pneumothorax, hemothorax, pulmonary contusion etc) as aggregated measures of thoracic injury severity, presuming them to be co-linear with number of ribs fractured. This methodology is more translatable to actual bedside application.
      We also did not assess whether the RCRI led to any cardioprotective therapies, but that was not the goal of the study. There has been data suggesting that therapies such as beta-blockade could mitigate the physiological stress reaction to the traumatic injury which might cause adverse cardiac outcomes and increased mortality in geriatric patients with hip fractures. The protective association of beta-blockade therapy increased with increasing cardiac risk.[
      • Ismail AM
      • Ahl R
      • Forssten MP
      • Cao Y
      • Wretenberg P
      • Borg T
      • et al.
      The interaction between pre-admission β-blocker therapy, the revised cardiac risk index, and mortality in geriatric hip fracture patients.
      ] We sought to assess whether the RCRI accurately predicted risk in elderly patients with unisystem and limited injury. While it was not possible to find evidence of a statistically significant association between RCRI 1 and adverse outcomes in the subgroup analysis, this does not necessarily indicate that such an association does not exist. A significant proportion of patients were removed when excluding intrathoracic injuries, which further reduced the already relatively small event rate. This result may consequently indicate a lack of statistical power rather than a lack of a clinically relevant relationship. Nonetheless, this study explicitly excludes all polytraumatized patients, and thus interpretation of the data should be limited to emergency management of elderly patients with traumatic rib fractures. Finally, we did not compare the RCRI to other assessment tools, but this exploratory study intended only to determine if the RCRI was suitable to use following injury in a specific subset of injured patients.

      Conclusion

      The RCRI is an easy and rapid indicator for risk stratification of elderly patients presenting with rib fractures who are managed conservatively. Patients with an elevated RCRI should be deemed high-risk and specifically assessed for the need for advanced monitoring or cardioprotective therapies during inpatient care. This study suggests that the RCRI is a good candidate for risk assessment following complex unisystem injury in geriatric patients.

      Source of Funding/ Support

      No financial support or funding was received for the presented work.

      Author Contributions

      GAB: study design, analysis and interpretation of data, drafting and revision of manuscript
      CCD: study design, interpretation of data, drafting and revision of manuscript
      LJK: analysis and interpretation of data, drafting and revision of manuscript
      BS: study design, data acquisition, interpretation of data, drafting and revision of manuscript
      NDM: study design, interpretation of data, drafting and revision of manuscript
      AMI: interpretation of data, drafting and revision of manuscript
      YC: analysis and interpretation of data, drafting and revision of manuscript
      MPF: study design, analysis and interpretation of data, drafting and revision of manuscript
      SM: study design, analysis and interpretation of data, drafting and revision of manuscript

      Declaration of Competing Interest

      The authors have no conflicts of interest to declare and have received no financial benefit in the execution of this study.

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