Anterior lumbar spinal fusion perioperative morbidity and mortality utilizing the National Inpatient Sample (NIS): 2005-2013

BACKGROUND CONTEXT

Minimally invasive approaches to the lumbar spine have become increasingly popular for the treatment of degenerative conditions and deformity correction. Anterior lumbar interbody fusion (ALIF) is one type of approach to the lumbar spine that has seen a massive increase in utilization over the past two decades. However, large scale studies evaluating the overall morbidity and mortality of this procedure are scarce. The National Inpatient Sample (NIS) serves as the single largest all-payer inpatient database in the United States and provides weights for nationally representative estimates. For this reason, it can be used to provide an approximation of the overall perioperative morbidity and mortality statistics for procedures such as ALIF.

PURPOSE

To evaluate the perioperative morbidity and mortality, as well as demographics, of patients undergoing lumbar spinal fusion via an anterior approach from 2005 to 2013.

STUDY DESIGN/SETTING

National Inpatient Sample Database Study

PATIENT SAMPLE

A total of 27,912 patients who underwent ALIF from 2005-2013 identified using the NIS database.

OUTCOME MEASURES

(1) Demographics (age, gender, hospital region and teaching status, insurance status, race/ethnicity, household income and Charlson Comorbidity Index [CCI] score); 2) frequencies of complications (pulmonary embolism [PE], deep venous thrombus [DVT], infection, cardiac, hematoma, durotomy); and 3) mortality rate.

METHODS

The NIS database was reviewed from 2005 to 2013. Patients undergoing elective lumbar fusion surgery via an anterior approach were identified by ICD-9 code. Indications specific to the lumbar spine, such as lumbar degenerative disc disease, herniated disc, stenosis or radiculopathy were also identified by their respective ICD-9 codes. Demographics including age, sex, hospital region and teaching status, insurance status, race/ethnicity, median household income and CCI score were assessed. Frequencies of complications including PE, DVT, infection, cardiac, hematoma, durotomy and mortality were also analyzed. Statistical analysis involved T tests, χ 2 analysis and binary logistic regression with p<0.001 denoting significance.

RESULTS

We identified 27,912 patients which represented an estimated 137,928 of weighted patients hospitalized for primary anterior lumbar spine fusion. Patients undergoing anterior lumbar fusion had a mean age of 55.4 (SD±14.3) with 55.3% female patients. The majority of patients were white (82.2%), privately insured (50.4%), had a median household income of $48,000-62,999 (27.1%) and had a CCI score of 0.44 (SD±0.8). The majority of procedures were performed in the South region (39.5%), in nonteaching hospitals (54.5%), in hospitals that were private or not-for-profit (70.4%). Bone morphogenic protein (BMP) was used in 43.4% of cases. The most common complication was durotomy (1.2%) followed by cardiac complications and hematoma (0.7%) with the least common being PE (0.1%). The mortality rate was 0.2% for this procedure.

CONCLUSIONS

This study provides valuable data on the patient demographics and complications of ALIF across the United States. ALIF has a low complication and mortality rate. We expect, with the advancements in instrumentation, success rate of fusions, and an aging population, that anterior fusion will continue to see an increase in utilization by spine surgeons across the country.

FDA DEVICE/DRUG STATUS

This abstract does not discuss or include any applicable devices or drugs.