Introduction

Degenerative and traumatic disorders of the lumbar spine can be treated with spinal fusion. There are known complications following spinal fusion; however, chronic hyperlipidemia has not been examined for its impact on perioperative complications. Hence, the purpose of this study was to compare the perioperative complications of lumbar spinal fusion in patients with and without chronic hyperlipidemia.

Methods

This study was conducted using the MSpine division of the PearlDiver database. The study included patients with or without chronic hyperlipidemia who had lumbar spinal fusions between 2010 and the first quarter of 2019. The appropriate Current Procedural Terminology (CPT) codes were used to identify patients with single- and multi-level lumbar spinal fusion surgeries. The International Classification of Diseases (ICD-9 and ICD-10) codes were used to identify patients with chronic hyperlipidemia. Using relevant ICD-9, ICD-10, and CPT codes, we retrieved perioperative surgical and medical complications. Propensity score matching analysis was conducted to control for the confounding factors, including age, gender, and Elixhauser Comorbidity Index (ECI). Chi-square test was applied to compare the incidence of complications among patients with and without hyperlipidemia.

Results

In total, 65674 patients with hyperlipidemia (n=18395) and without hyperlipidemia (n=47279) had single-level lumbar fusions. Propensity score matching resulted in 16930 patients in each group.

Patients with hyperlipidemia compared to patients without hyperlipidemia had higher rates of wound complications [481 (2.8%) versus 357 (2.1%), P<0.001], surgical site infection [370 (2.2%) versus 231 (1.4%), P<0.001], failed back syndrome [1914 (11.3%) versus 1605 (9.5%), P<0.001], hardware removal [1006 (5.9%) versus 761 (4.5%), P<0.001], deep venous thrombosis/pulmonary embolism [264 (1.6%) versus 216 (1.3%), P=0.031], myocardial infarction [81 (0.5%) versus 23 (0.1%), P<0.001], cerebrovascular accident [86 (0.5%) versus 39 (0.2%), P<0.001], renal failure [305 (1.8%) versus 197 (1.2%), P<0.001], sepsis [103 (0.6%) versus 51 (0.3%), P<0.001], urinary tract infection/incontinence [697 (4.1%) versus 436 (2.6%), P<0.001].

In total, 48928 patients with hyperlipidemia (n=15527) and without hyperlipidemia (n=33401) had multi-level lumbar fusions. Propensity score matching resulted in 14218 patients in each group.

Patients with hyperlipidemia compared to patients without hyperlipidemia had higher rates of nerve root injury [33 (0.2%) versus 17 (0.1%), P=0.034], wound complications [624 (4.4%) versus 508 (3.6%), P<0.001], surgical site infection [438 (3.1%) versus 307 (2.2%), P<0.001], failed back syndrome [2024 (14.2%) versus 1642 (11.5%), P<0.001], hardware removal [1146 (8.1%) versus 885 (6.2%), P<0.001], revision [922 (6.5%) versus 1055 (7.4%), P=0.002], myocardial infarction [120 (0.8%) versus 41 (0.3%), P<0.001], renal failure [472 (3.3%) versus 313 (2.2%), P<0.001], urinary tract infection/incontinence [810 (5.7%) versus 618 (4.3%), P<0.001].

Discussion

The findings of this study showed that following single- or multi-level lumbar fusions, chronic hyperlipidemia is associated with an increased risk of wound complications, surgical site infection, failed back syndrome, hardware removal, myocardial infarction, renal failure, and urinary tract infection/incontinence. Additionally, chronic hyperlipidemia is associated with an increased risk of nerve root injury and revision rates after multi-level lumbar fusions.