Background:

The substantial risk for medical complication after adult spinal deformity (ASD) surgery is well known. However, the timing of medical complications during the inpatient stay have not been previously described. Accurate anticipation of complications and adverse events may improve patient counseling and post-operative management.

Purpose:

(1) Describe the rate of medical complication and adverse events by post-operative day after ASD surgery and (2) determine whether early ambulation is protective for complications STUDY DESIGN/SETTING: : Single institution retrospective cohort study PATIENT SAMPLE: : 235 patients with ASD who underwent posterior-only fusion of the lumbar spine (≥5 levels to the pelvis) between 2013-2020 OUTCOME MEASURES: : Medical complications, categorized per the International Spine Study Group-AO system (cardiopulmonary [CP], gastrointestinal [GI], central nervous system [CNS], infectious [non-surgical site], and renal) and adverse events (post-operative blood transfusion, urinary retention, and electrolyte abnormalities) METHODS: : Patients were identified from an institutional ASD database. Outcome measures were classified by the first post-operative day the event was recognized. Demographics, year of surgery, surgical factors, radiographic parameters, surgical invasiveness (ASD-S Index), frailty (Modified Frailty Index-5 [mFI-5]), Charlson Comorbidity Index (CCI), obstructive sleep apnea (OSA), smoking, preoperative opioid use, depression, and post-operative day of ambulation were assessed as risk factors for inpatient medical complications.

Results:

After exclusions of patients with incomplete medical chart data, 191 patients were available for analysis, mean age 66±10 yrs, BMI 28±5 kg/m2, PI-LL 24±20°, T1PA 28±13°. Inpatient medical complications occurred in 55 (28.8%) patients; adverse events occurred in 137 (71.7%). Length of stay was higher in patients with medical complications (mean 8.5±3.8 vs. 5.8±2.3 days, p<0.001). However, for patients who had an adverse event, but no medical complication, LOS was comparable (p>0.05). Most medical complications occurred by POD3 (58% of all complications). Risk (defined as the proportion of patients with that complication out of all inpatients that day) of CNS, CP, and GI complication peaked early in the post-operative course (CNS on POD1 [2.1% risk]; GI on POD2 [3.7%]; CP on POD3 [2.7%]). Risk for infectious and renal complications (infectious POD8 [2.7%]; renal POD7 [0.9%]) peaked later (Figure 1). On univariate analysis, patients with medical complications had higher rates of OSA (9.1% vs. 2.2%, p=0.045), ASD-S (45.9 vs. 40.8, p=0.04), max coronal cobb (46.9 vs. 36.7°, p=0.003), ASA class (2.5 vs. 2.3, p=0.01), and POD of ambulation (1.9 vs. 1.3, p=0.01). On multivariate logistic regression (c-statistic 0.78), larger coronal cobb and later POD of ambulation were independent risk factors for complications (OR 1.04, 95% CI 1.01-1.07 and OR 2.3, 95% CI 1.2-4.7, respectively).

Conclusions:

Our data may inform peri-operative management and patient expectations for hospitalization after ASD surgery. Early ambulation may reduce the risk of complications.