This cross-sectional study determines the association of frailty with morbidity and mortality in patients undergoing emergency general surgery based on the level of procedural risk.
Key Points
Question
Is level of procedural risk associated with frailty and mortality in emergency general surgery patients?
Findings
In this cross-sectional study of 882 929 emergency general surgery admissions, frailty was significantly associated with mortality. After stratified analysis, this association remained significant for high-risk procedures, and it was even greater within low-risk procedures.
Meaning
Procedural risk level is associated with frailty and mortality in emergency general surgery patients, and preoperative frailty assessment should be strongly considered even within low-risk procedures.
Abstract
Importance
In this aging society, older patients are more commonly undergoing emergency general surgery (EGS). Although frailty has been associated with worse outcomes in this population, EGS encompasses a heterogeneous mix of procedures.
Objective
To determine if the association of frailty with morbidity and mortality in EGS patients varies based on the level of procedural risk.
Design, Setting, and Participants
This cross-sectional study analyzed Medicare inpatient claims file (January 2007-December 2015) and included all inpatients who underwent 1 of 7 previously described EGS procedures shown to represent 80% of EGS volume, complications, and mortality nationally. Analysis took place from September 2019 to January 2020.
Exposures
The primary exposure of interest was risk procedural level. EGS procedures were stratified as high risk (excision of small intestine, excision of large intestine, peptic ulcer repair, lysis of peritoneal adhesions, and laparotomy) and low risk (appendectomy and cholecystectomy).
Main Outcomes and Measures
The primary outcome was overall 30-day mortality after discharge. Frailty was assessed using a claims-based frailty index. Multivariate logistic regression analysis was used and was stratified by risk level.
Results
A total of 882 929 EGS patients were included in this study (mean [SD] age, 77.9 [7.5] years; 483 637 [54%] were female). Overall mortality was 4.5% (n = 40 304). The frailty index classified 12.6% (n = 111 513) of patients as frail, and mortality within this group was 9.9% (n = 11 307). High-risk procedures represented 53% (n = 468 098) of the caseload, and mortality was 6.8% (n = 31 979). For low-risk procedures, mortality was 2% (n = 8325). Frailty was significantly associated with mortality (odds ratio, 1.64; 95% CI, 1.60-1.68). After stratified analysis, this association remained significant for high-risk (odds ratio, 1.53; 95% CI, 1.49-1.58) and low-risk (odds ratio, 2.05; 95% CI, 1.94-2.17) procedures.
Conclusions and Relevance
Frailty was significantly associated with mortality in patients undergoing EGS, with an even greater association in low-risk procedures. Preoperative frailty assessment is imperative even in low-risk procedures.
Introduction
Patients undergoing emergency general surgery (EGS) are more likely to die and to have a postoperative complication compared with those undergoing elective surgery.1,2,3 Globally, the population is aging rapidly, with those 65 years and older growing faster than any other age group. Additionally, it has been shown that this age group has higher rates of surgery compared with others.4,5 Consequently, the inherent risk of having an emergency procedure combined with older age results in worse outcomes and the utilization of more resources.6,7,8 However, other factors besides age need to be considered. Prior research has shown that frailty is a better predictor of mortality and morbidity compared with chronological age in this population.9
Frailty has been defined as an aging-related state of vulnerability to poor outcomes.10,11,12 Frailty can be conceptualized as a measure of physiologic reserve; as a consequence, frail older adults are less able to adapt and respond to stressors, such as acute illness or trauma, resulting in decompensation.4,8 Although the prevalence of frailty varies with the tool used, population-based studies have shown a positive association between frailty and age.1 As more older patients undergo surgery, frailty becomes a more important contributor to outcomes in the EGS setting.
The effect of frailty in morbidity and mortality after elective procedures has been extensively studied; however, its contribution to adverse postoperative outcomes after EGS has been recently established.2,7,13,14,15 This can be partially explained by the recent standardized definition of EGS, which includes 7 procedures that represent a majority of the EGS operative burden.3 However, the risk of complications and death differs greatly between these procedures.16 For example, appendectomy and cholecystectomy have much lower morbidity and mortality rates compared with the others, although they represent the largest proportion of cases.16 Therefore, our goal was to determine if the increased burden of morbidity and mortality of frailty in EGS patients varied based on the level of procedural risk.
Methods
Database
Patient data were obtained from the 100% Medicare Limited Data set inpatient file from January 2007 to December 2015. These administrative file claims contain data on encounters with the health care system of more than 55 million Medicare beneficiaries, which include US individuals 65 years or older. Each individual patient gets assigned a unique patient identifier, which allows the linkage of multiple admissions during the study. This study was approved by the Partners Healthcare Institutional Review Board, and patient consent was not needed.
Study Cohort
We included all adults (aged ≥65 years) who underwent an EGS procedure and survived to hospital discharge. These previously defined procedures were laparotomy (only cases with no secondary procedure were included), surgical treatment of ulcer of stomach or duodenum, lysis of adhesions, excision of small intestine, appendectomy, colectomy, and cholecystectomy.3 Patients who had an urgent or emergent admission and had surgery within 48 hours of admission were included. Patients with concurrent EGS procedures were excluded from the analysis.
Patient and Hospital Characteristics
Demographic characteristics such as age, sex, and race/ethnicity were collected. The Charlson Comorbidity Index (CCI) score, a validated score that uses 19 possible diagnoses to assess the association between mortality and perioperative complications in longitudinal data, was calculated and was considered as a continuous variable.17
Patient data were linked to the American Hospital Association Annual Survey, which provided data on hospital structural features. Hospital characteristics included teaching status (teaching vs nonteaching), hospital bed size (<200 vs ≥200 beds), and geographic location (South, Midwest, Northeast, West).
Exposure Assessment
Our main exposure was risk procedural level. We divided EGS procedures into high and low risk. Based on earlier work from our group, appendectomy and cholecystectomy were defined as low risk, and laparotomy, colectomy, small-bowel resection, peptic ulcer repair, and lysis of adhesions were defined as high risk.16
To define frailty, we used a claims-based frailty index modeled off the Rockwood Frailty Index. This index has been previously validated using Medicare data.18,19 The claims-based frailty index, with values from 0 to 1 (higher indicates more frailty) was determined by assigning defined weights to 93 administrative codes for durable medical equipment claims, comorbid conditions, and health care facility use in the 12 months preceding an admission. A cutoff score of 0.25 or higher was considered to determine if a patient was frail. Therefore, patients with a claims-based frailty index score less than 0.25 were considered not frail and those with a score of 0.25 or higher were deemed frail.
Outcomes Assessment
Mortality within 30 days of discharge was the main outcome of interest. This was extracted from the Medicare Beneficiary Summary File. Secondary outcomes included discharge disposition (home vs other) and readmission.
Data Analysis
t Tests and χ2 tests were performed for comparisons between continuous variables and categorical variables, respectively. Initially, risk factors associated with mortality were identified using logistic regression. All covariates with a P value of .10 or less or those that were considered potential confounders were included in model building. Covariates included in model building were age, sex, race/ethnicity, CCI score, number of hospital beds, hospital region, hospital teaching status, and type of EGS procedure. All variables had complete data for nearly all patients (approximately 99%), and complete cases analyses were used. The association of frailty and mortality was then determined by using multivariate logistic regression, adjusting for previously described covariates. We then performed a stratified analysis by procedural risk level (high risk vs low risk) to determine if there was a change in the association of frailty and mortality. Moreover, because these EGS procedures include both the laparoscopic and open approach and the use of laparoscopy reduces morbidity and mortality, we performed a sensitivity analysis to examine the association between outcome and frailty for laparoscopic procedures vs open. Statistical analyses were conducted using Stata version 15 (StataCorp), and the threshold for statistical significance was set at 2-sided P < .05. Analysis took place from September 2019 to January 2020.
Results
Population
We included 882 929 patients who underwent an EGS procedure. The mean (SD) age was 77.9 (7.5) years, 483 637 (54%) were female, and 778 868 (88.21%) were White. High-risk procedures represented 53% (n = 468 098) of the caseload. Cholecystectomy (342 444 [38.78%]) was the most common procedure, followed by colectomy (155 808 [17.65%]) and peptic ulcer repair (135 975 [15.40%]).
Frail vs Nonfrail Patients
Of all EGS patients, 111 513 (12.63%) were deemed frail. There were significant differences in demographics and clinical characteristics between frail and nonfrail patients (Table 1). Frail patients were less likely to be female, younger, and White than nonfrail patients (P < .001). However, they were more likely to have a higher CCI score compared with nonfrail patients (P < .001) (Table 1). Regarding hospital characteristics, frail patients were more likely to be seen at teaching and larger hospitals (P < .001) (Table 1). While other variables were statistically significant, the difference might not have been clinically meaningful. Cholecystectomy and large-bowel resection were the most common procedures among nonfrail patients. However, cholecystectomy and surgical treatment of ulcer were the most common procedures in frail patients. Of patients undergoing high-risk procedures, 70 486 (15.06%) were frail. Among patients undergoing low-risk procedures, 41 027 (9.89%) were deemed frail. Frail patients were significantly more likely to be readmitted (40 516 [36%] vs 146 592 [19%]; P < .001) compared with nonfrail patients. Frail patients were significantly less likely to be discharged home (27 878 [25%] vs 439 707 [57%]; P < .001) compared with nonfrail patients.
Table 1. Characteristics of Patients With vs Without Frailty After Emergency General Surgery.
| Variable | Frail (n = 111 513) | Not frail (n = 771 416) | P value |
|---|---|---|---|
| Age, median (IQR), y | 79.9 (73.6-85.5) | 77.1 (71.3-83.4) | <.001 |
| Sex | |||
| Female | 69 547 (62.4) | 414 090 (53.7) | <.001 |
| Male | 41 966 (37.6) | 357 326 (46.3) | |
| Race/ethnicity | |||
| White | 95 056 (85.2) | 683 812 (88.6) | <.001 |
| Black | 11 211 (10.1) | 49 225 (6.4) | |
| Othera | 5246 (4.7) | 38 379 (5.0) | |
| CCI score, median (IQR) | 3 (2-5) | 0 (0-2) | <.001 |
| Teaching hospital status | |||
| Teaching | 16 254 (14.6) | 108 038 (14.0) | <.001 |
| Nonteaching | 95 259 (85.4) | 663 378 (86.0) | |
| No. of hospital beds | |||
| 0-199 (Small) | 32 470 (29.1) | 240 609 (31.2) | <.001 |
| ≥200 (Large) | 79 043 (70.9) | 530 807 (68.8) | |
| Type of surgery | |||
| Cholecystectomy | 37 677 (33.8) | 304 767 (39.5) | <.001 |
| Appendectomy | 3350 (3.0) | 69 037 (9.0) | |
| Laparotomy | 1960 (1.8) | 9796 (1.3) | |
| Colectomy | 20 610 (18.5) | 135 198 (17.5) | |
| Lysis of adhesions | 11 007 (9.9) | 74 507 (9.7) | |
| Peptic ulcer repair | 27 318 (24.5) | 108 657 (14.1) | |
| Small-bowel resection | 9591 (8.6) | 69 454 (9.0) |
Abbreviations: CCI, Charlson Comorbidity Index; IQR, interquartile range.
The other category includes Asian, Hispanic, and North American Native.
Frailty and Mortality
Overall mortality for the entire cohort was 4.5% (n = 40 304). In unadjusted analysis, frail patients were more likely to die (11 037 [9.90%] vs 29 267 [3.79%]; P < .001) compared with nonfrail patients. Within high-risk procedures, overall mortality was 6.83% (31 979 of 468 098), and frail patients were more likely to die than nonfrail patients (8620 [12.23%] vs 23 359 [5.87%]; P < .05). Within low-risk procedures, overall mortality was 2.01% (8325 of 414 831), and frail patients were more likely to die than nonfrail patients (2417 [5.89%] vs 5908 [1.58%]; P < .05).
In adjusted analysis (controlling for patient- and hospital-level characteristics), frailty was independently associated with mortality (adjusted odds ratio [aOR], 1.64; 95% CI, 1.60-1.68). We also found that age (OR, 1.05; 95% CI, 1.05-1.06), sex (OR, 0.87; 95% CI, 0.86-0.89), CCI score (OR, 1.16; 95% CI, 1.15-1.16), hospital volume (OR, 0.94; 95% CI, 0.92-0.97), and hospital teaching status (OR, 0.86; 95% CI, 0.83-0.89) were associated with mortality (P < .001) (Table 2).
Table 2. Multivariate Analysis of Mortality After Emergency General Surgery.
| Variable | Odds ratio (95% CI) | P value |
|---|---|---|
| Age, y | 1.05 (1.05-1.06) | <.001 |
| Sex | ||
| Male | 1 [Reference] | NA |
| Female | 0.87 (0.86-0.89) | <.001 |
| Race/ethnicity | ||
| White | 1 [Reference] | NA |
| Black | 0.93 (0.90-0.97) | .99 |
| Othera | 0.87 (0.83-0.92) | <.001 |
| CCI score | 1.16 (1.15-1.16) | <.001 |
| Frailty status | ||
| Not frail | 1 [Reference] | NA |
| Frail | 1.64 (1.60-1.68) | <.001 |
| Teaching hospital status | ||
| Nonteaching | 1 [Reference] | NA |
| Teaching | 0.86 (0.83-0.89) | <.001 |
| Hospital size | ||
| ≥200 Beds (large) | 1 [Reference] | NA |
| 0-199 Beds (small) | 0.94 (0.92-0.97) | <.001 |
| Region | ||
| West | 1 [Reference] | NA |
| Northeast | 0.87 (0.84-0.91) | <.001 |
| Midwest | 1.07 (1.03-1.10) | <.001 |
| South | 1.16 (1.12-1.20) | <.001 |
| Type of surgery | ||
| Small-bowel resection | 1 [Reference] | NA |
| Cholecystectomy | 0.31 (0.30-0.32) | <.001 |
| Appendectomy | 0.19 (0.18-0.21) | <.001 |
| Laparotomy | 1.99 (1.87-2.11) | <.001 |
| Colectomy | 1.14 (1.11-1.18) | <.001 |
| Lysis of adhesions | 0.58 (0.55-0.60) | <.001 |
| Peptic ulcer repair | 0.62 (0.60-0.64) | <.001 |
Abbreviations: CCI, Charlson Comorbidity Index; NA, not applicable.
The other category includes Asian, Hispanic, and North American Native.
After stratified analysis, the association between frailty and mortality remained significant within patients undergoing high-risk procedures (aOR, 1.53; 95% CI, 1.49-1.58; P < .001) (Table 3) and low-risk procedures (aOR, 2.05; 95% CI, 1.94-2.17; P < .001) (Table 4). This association was greater in low-risk procedures.
Table 3. Multivariate Analysis of Mortality After High-risk Emergency General Surgery Procedures.
| Variable | Odds ratio (95% CI) | P value |
|---|---|---|
| Age, y | 1.05 (1.04-1.05) | <.001 |
| Sex | ||
| Male | 1 [Reference] | NA |
| Female | 0.87 (0.85-0.89) | <.001 |
| Race/ethnicity | ||
| White | 1 [Reference] | NA |
| Black | 0.90 (0.86-0.94) | .04 |
| Othera | 0.91 (0.85-0.97) | .21 |
| CCI score | 1.15 (1.15-1.16) | <.001 |
| Frailty status | ||
| Not frail | 1 [Reference] | NA |
| Frail | 1.53 (1.49-1.58) | <.001 |
| Teaching hospital status | ||
| Nonteaching | 1 [Reference] | NA |
| Teaching | 0.88 (0.85-0.91) | <.001 |
| Hospital size | ||
| ≥200 Beds (large) | 1 [Reference] | NA |
| 0-199 Beds (small) | 0.93 (0.91-0.96) | <.001 |
| Region | ||
| West | 1 [Reference] | NA |
| Northeast | 0.89 (0.85-0.93) | <.001 |
| Midwest | 1.07 (1.03-1.18) | <.001 |
| South | 1.15 (1.11-1.20) | <.001 |
| Type of surgery | ||
| Small bowel resection | 1 [Reference] | NA |
| Laparotomy | 1.96 (1.84-2.08) | <.001 |
| Colectomy | 1.14 (1.11-1.18) | <.001 |
| Lysis of adhesions | 0.58 (0.56-0.61) | <.001 |
| Peptic ulcer repair | 0.63 (0.60-0.65) | <.001 |
Abbreviations: CCI, Charlson Comorbidity Index; NA, not applicable.
The other category includes Asian, Hispanic, and North American Native.
Table 4. Multivariate Analysis of Mortality After Low-risk Emergency General Surgery Procedures .
| Variable | Odds ratio (95% CI) | P value |
|---|---|---|
| Age, y | 1.07 (1.07-1.08) | <.001 |
| Sex | ||
| Male | 1 [Reference] | NA |
| Female | 0.89 (0.85-0.93) | <.001 |
| Race/ethnicity | ||
| White | 1 [Reference] | NA |
| Black | 1.10 (1.01-1.21) | <.001 |
| Othera | 0.80 (0.72-0.89) | <.001 |
| CCI score | 1.17 (1.16-1.18) | <.001 |
| Frailty status | ||
| Not frail | 1 [Reference] | NA |
| Frail | 2.05 (1.94-2.17) | <.001 |
| Teaching hospital status | ||
| Nonteaching | 1 [Reference] | NA |
| Teaching | 0.75 (0.70-0.82) | <.001 |
| Hospital size | ||
| ≥200 Beds (large) | 1 [Reference] | NA |
| 0-199 Beds (small) | 0.99 (0.94-1.04) | .84 |
| Region | ||
| West | 1 [Reference] | NA |
| Northeast | 0.83 (0.76-0.90) | <.001 |
| Midwest | 1.06 (0.98-1.13) | .01 |
| South | 1.16 (1.09-1.24) | <.001 |
| Type of surgery | ||
| Cholecystectomy | 1 [Reference] | NA |
| Appendectomy | 0.68 (0.63-0.73) | <.001 |
Abbreviations: CCI, Charlson Comorbidity Index; NA, not applicable.
The other category includes Asian, Hispanic, and North American Native.
Sensitivity analysis showed that results were similar when stratifying by laparoscopic vs open approach. Within laparoscopic procedures, frailty was significantly associated with mortality in patients undergoing high-risk procedures (aOR, 1.38; 95% CI, 1.29-1.46; P < .001) and low-risk procedures (aOR, 2.08; 95% CI, 1.95-2.23; P < .001). Within open procedures, frailty was also significantly associated with mortality in patients undergoing high-risk procedures (aOR, 1.63; 95% CI, 1.58-1.69; P < .001) and low-risk procedures (aOR, 1.91; 95% CI, 1.71-2.13; P < .001). Regardless of surgical approach, the association of frailty and mortality remained significant and was greater in low-risk procedures.
Discussion
Our study found that 13% of older patients undergoing EGS were frail, of which 10% died. Frail patients had higher rates of mortality, readmission, and were more likely to be discharged to a facility other than home. Mortality was higher among patients undergoing high-risk EGS procedures. Additionally, we found that frailty was independently associated with mortality and this association was stronger within low-risk procedures, regardless of operative approach. This suggests that even EGS procedures associated with less complex intraoperative and postoperative care may require better planning for frail patients. As far as we know, no previous studies have evaluated the effect of EGS procedural risk level in the association of frailty and mortality.
Our findings are congruent with other studies of frailty in surgical patients.14,20,21 McIsaac et al6 found that preoperative frailty-defining diagnoses were associated with a significantly increased risk of 1-year mortality following major elective noncardiac surgery. Moreover, Farhat et al22 found that a frailty index was an important predictive variable in EGS patients older than 60 years. However, we need to emphasize that the emergent or urgent quality of the cases determines a difference in the care provided compared with those performed electively. We also need to take into account that older patients, on top of the acute surgical condition, are more likely to have chronic diseases. This combination limits the time necessary for the appropriate patient optimization before the surgical procedure. For elective surgeries, planning allows more time to optimize the patient and have a more detailed discussion as part of the shared decision-making process, which has been shown to lead to better outcomes in frail patients. However, since EGS is becoming more prevalent in frail older patients, there is a need for tailored strategies to accurately and promptly evaluate the full risk of this specific population. Although several interventions focused on exercise, nutrition, and drug therapies have been implemented as part of the patient optimization process before elective surgery, greater efforts are needed to facilitate this process in emergent situations.23 Our data suggest several specific opportunities to improve patient care. These include rigorous evaluation of frailty specific risk; thorough discussions between patients, families, and the surgical team to determine whether or not to have the operation; and the type of care needed postoperatively.
The association between frailty and mortality varied based on the risk category of the EGS procedure. Unexpectedly, this effect modification was more pronounced on EGS procedures with low risk level (appendectomy and cholecystectomy), which usually require less complex care and having lower risk-adjusted odds of mortality compared with high-risk procedures. It is also worth noting that frail individuals undergoing a low-risk procedure have about the same risk as nonfrail individuals undergoing a high-risk procedure, which effectively suggests that in a frail patient even appendectomy and cholecystectomy are high risk. Interestingly, these results were similar even after stratifying for laparoscopic and open procedures. However, we need to consider that some of the excess mortality in the open procedure group could be reduced by using a laparoscopic approach because minimally invasive techniques have been shown to have a clear benefit in elderly patients. This is especially true in frail patients whose recovery can be greatly compromised by more invasive procedures.24
A possible explanation for the effect modification previously described could be that because these procedures are known to have lower morbidity and mortality, they are not truly deemed as high risk, and consequently, being frail did not have a definitive weight toward the decision to proceed with the operation. Therefore, being frail did not necessarily affect the surgical team’s eagerness to perform a low-risk less complex procedure in a patient with a high baseline risk. Within the elective surgery setting, Shinall et al25 reported an analogous pattern, where there was a stronger association between frailty and mortality in frail patients undergoing low-stress procedures (ie, total joint replacement) compared with those undergoing moderate-high stress procedures such as liver, kidney, and pancreatic surgery. Consequently, risk stratification in the preoperative setting must include a proactive evaluation of frailty by all perioperative clinicians, regardless of the complexity or risk of the procedure.23
Our results suggest that frailty screening should be applied universally because even low-risk procedures may be high risk among patients who are frail. In these situations, some interventions can be helpful. First, risks associated with frailty should be thoroughly discussed with patients as part of the shared decision-making process. If electing to pursue surgical intervention, patient optimization could be targeted if possible, within the short available time. Also, geriatric comanagement would be one strategy to reduce postoperative complications such as delirium.26,27 Moreover, geriatric nursing protocols can improve mobility and reduce functional decline in these patients.26
Limitations
Our study has several limitations. The Medicare inpatient file claims database includes a group of homogeneous insured patients older than 65 years; thus, this may limit the generalizability of our findings. Similar to all administrative databases, Medicare claims do not contain more detailed clinical data for more appropriate risk adjustment. We considered that including the frailty index and CCI score in our adjusted analysis addressed this limitation at least partially. However, these score calculations are reliant on coding and cannot be validated against actual patient data. Additionally, the term laparotomy was used to represent patients who had a Current Procedural Terminology code for laparotomy and no secondary code; thus, they may represent either negative or nontherapeutic laparotomy. Although we are unable to know which, this system has been well established in the literature.3,16 Another important limitation is that there are no available data ascertaining the cause of death in these patients. We also acknowledge that the score we used to determine frailty was mainly developed as a research tool and it was not intended for clinical use. Therefore, it cannot be used at the bedside because of the requirement for extensive administrative data. However, this claims-based metric has been validated against some common tools more easily applicable in the clinical setting.19
Conclusions
This study showed that frailty was significantly associated with mortality in patients undergoing EGS, with an even greater association in low-risk procedures. Preoperative frailty assessment is imperative even in low-risk procedures. Further studies should focus on identifying areas of improvement to provide better care for this frail population undergoing EGS.
References
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