Urologic Oncology: Seminars and Original Investigations
Original articleValidation of a frailty index in patients undergoing curative surgery for urologic malignancy and comparison with other risk stratification tools☆
Introduction
Frailty is a growing issue for surgeons, as frail patients have worse health outcomes with increased mortality rates, hospitalizations, and institutionalization rates [1]. Frailty is a medical syndrome with multiple contributors and is characterized by diminished strength, endurance, and reduced physiologic function, increasing an individual׳s vulnerability to dependency and death [2]. Frailty is associated with poor oncological outcomes such as disease progression and disease-specific mortality [3].
The Canadian Study of Health and Aging Frailty Index (CSHA-FI) is a clinically validated measure of frailty that includes the extent of comorbidities and quality-of-life variables in an accumulating deficit model of frailty [4]. Rockland et al. defined frailty as a function of the severity of a patient׳s comorbidities and declines in activities of daily living [4]. They validated their accumulating deficit model of frailty showing that it was equivalent to the phenotypic frailty model defined by the Fried frailty index, which takes into account factors such as walking speed and weight loss [5]. Abbreviated versions of the CSHA-FI have been validated as preoperative risk stratification tools in prospective and retrospective fashion in general surgery, gynecological oncology, and orthopedic surgery [6], [7], [8], [9], [10], [11]. An abbreviated version has been validated retrospectively using the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) data set among patients undergoing vascular surgery, colectomy, and emergency and elective general surgery and cardiothoracic patients undergoing lobectomies [11], [12], [13], [14], [15]. In all cases, frailty measured by increasing score in the frailty index was associated with adverse outcomes.
We used the variables from the CSHA-FI mapped to the ACS-NSQIP data set to create a modified 15-point frailty index (mFI), with additional variables pertinent to our patient population in a model of frailty that measures accumulating deficits [4], [5], [16]. We validated our modified FI in patients undergoing genitourinary procedures to see how frailty and comorbidities affect patients across the most common oncological surgeries in urology: prostatectomy, cystectomy, nephrectomy, and nephroureterectomy (Neph-U).
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Material and methods
Under the data use agreement of the ACS, we reviewed the NSQIP participant use files from 2005 to 2013. The NSQIP database is a national, validated, outcomes-based data set that is managed by the ACS. The hospitals participating in the consortium are the source of the data used herein; they have not verified, and are not responsible, for the statistical validity of the data analysis or the conclusions we have derived.
We collected 11 variables from the CSHA-FI matched to preoperative variables
Results
The ACS-NSQIP database was queried for 41,681 patients who met our selection criteria with the following clinical and demographic characteristics (Table 2). Patients undergoing cystectomy had the highest 30-day mortality rate (2.6%) and Clavien-Dindo IV complications (9.5%); those undergoing prostatectomy had the lowest 30-day mortality rate (0.2%) and Clavien-Dindo IV complications (1.1%).
For patients undergoing prostatectomy, increasing mFI was associated with increased rates of Clavien-Dindo
Discussion
When compared with healthy patients, frail patients who are exposed to stressors such as surgical intervention may have disproportionate decompensation because of a lack of physiologic reserve [22]. Therefore, the risk-benefit ratio of surgery should include frailty and severity of comorbidities to capture the full risk of a surgical candidate undergoing a surgical oncological intervention.
In this retrospective study, using the ACS-NSQIP data set, we validated a FI, modified it for patients
Conclusion
There has been a growing need for a structured, evidence-based preoperative evaluation for frail patients undergoing oncological genitourinary surgery [28], [29]. Our modified FI was associated with worse outcomes comparable to those of existing risk stratification tools when assessing 30-day mortality and Clavien-Dindo IV outcomes. When our mFI was combined with the ASA class risk stratification, it was superior to all existing risk stratification tools, indicating potential clinical
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Funding for the lead author and primary investigator was awarded through the National Institute of Diabetes and Digestive and Kidney Diseases via a National Institute of Health, Bethesda, MD, USA T35 Grant 5 T35 DK 93430-3.