A Modified Frailty Index Predicts Complications Following Pedicle Subtraction Osteotomy

Introduction: Frailty is a common geriatric syndrome that is known to predispose patients to poor surgical outcomes. We designed a novel, modified 8 item index, specifically designed to assess patients’ frailty prior to orthopedic procedures. This study aimed to assess the prognostic value of a Modified Frailty Index (MFI) in the setting of Pedicle Subtraction Osteotomy.

Methods: Querying the American College of Surgeons - National Surgical Quality Improvement Program (ACS - NSQIP), we assessed 339 patients undergoing Pedicle Subtraction Osteotomy (PSO). Patients were assessed for the presence of the eight comorbidities included in our MFI - severe obesity (BMI > 35), diagnosis of osteoporosis, non-independent function status prior to surgery, congestive heart failure within 30 days of surgery, hypoalbuminemia (serum albumin < 3.5), hypertension requiring medication, type 1 or type 2 diabetes, and a history of COPD or pneumonia - and assigned to an MFI class based on number of comorbidities. MFI 0 represented patients with none of the selected comorbidities, MFI 1 included those with one or two, MFI 2 included those with 3 or 4, and MFI 3 represented those with 5 or more. Multivariate regression was performed to assess the predictive value of each MFI class on postoperative outcomes.

Results: MFI class was a strong predictor of outcomes. Higher MFI was associated with greater odds of adverse discharge (OR 7.99; p=0.046) and reoperation (OR 16.38; p< 0.001). Increasing MFI also corresponded to increased odds of Clavien-Dindo grade IV (life-threatening) complications (OR 13.18; p=0.004), renal complications (OR 9.40; p=0.024), sepsis (OR 8; p=0.046), surgical site infections (OR 9.71; p=0.021), and unplanned intubation (OR 12.41; p=0.006).

Conclusion : Our MFI is a simple, but powerful predictor of outcomes following PSO. It is imperative that spine surgeons assess patient comorbidities and frailty prior to surgery. This assessment tool can be used to screen a patient's frailty level and for risk stratification purposes.