Incidence and Mortality of Cardiac Events in Lumbar Spine Surgery

Steven J. Fineberg, MD; Kasra Ahmadinia, MD; Alpesh A. Patel, MD, FACS; Matthew Oglesby, BA; Kern Singh, MD

Disclosures

Spine. 2013;38(16):1422-1429. 

In This Article

Abstract and Introduction

Abstract

Study Design. Retrospective national database analysis.

Objective. A population-based database was analyzed to characterize the incidence, mortality, and associated risk factors for cardiac events in lumbar spine surgery.

Summary of Background Data. Cardiac events are a leading cause of perioperative mortality in spinal surgery. The incidence of these complications after lumbar surgery is not well characterized on a national level.

Methods. Data from the Nationwide Inpatient Sample was obtained from 2002 to 2009. Patients undergoing lumbar decompression or lumbar fusion for degenerative etiologies were identified. Patient demographics, incidence of cardiac complications, comorbidities, and mortality were assessed. Statistical analysis was performed using Student t test for discrete variables and [chi]2 test for categorical data. Logistic regression was used to identify independent predictors for cardiac complications.

Results. A total of 578,457 lumbar spine procedures were identified in the Nationwide Inpatient Sample from 2002 to 2009. The overall incidence of cardiac complications was 6.7 per 1000 cases. Cardiac events occurred more frequently in the lumbar fusion group, with a rate of 9.3 per 1000 cases, than in the lumbar decompression group, with a rate of 4.0 per 1000 (P < 0.0005). Patients with cardiac events were significantly older than patients without complications by 9.4 years (P < 0.0005). Patients with cardiac complications had statistically increased hospitalizations, costs, and mortality when a cardiac event was present (P < 0.0005). Logistic regression analysis demonstrated independent predictors for cardiac events to include age 65 years or older, acute blood loss anemia, and several comorbidities.

Conclusion. Our results demonstrated an overall incidence of 6.7 cardiac complications per 1000 lumbar spine surgical procedures from 2002 to 2009. Patients undergoing lumbar fusion were more likely to experience cardiac events than lumbar decompression patients. Cardiac events tend to occur in patients with noted risk factors and result in increased hospitalizations, costs, and mortality. On the basis of these findings, we think that patients with specified risk factors should be monitored closely and medically optimized in the perioperative period.

Introduction

As the population continues to age, an increasing number of patients have become candidates for lumbar spine surgery.[1] When appropriately indicated, lumbar spine surgery can provide significant relief to patients who have failed conservative treatment. It is estimated that nearly 500,000 lumbar spine procedures are performed in the United States annually.[2] Although many of these procedures are highly successful, as with any other surgery, there still are risks associated with the procedure.

A rare but devastating complication of lumbar spine surgery is a cardiac event. Perioperative cardiac events are the leading cause of mortality after non–cardiac surgery.[3,4] Previous studies have demonstrated that cardiac complications are associated with 0.2% to 13% of lumbar procedures.[4–11] Patients with these complications had a higher 2-year mortality rate than those without perioperative cardiac events.[5]

Understanding risk factors for cardiac events after lumbar surgery is imperative for their avoidance and management. Several risk factors for perioperative cardiac events in non–cardiac surgery have been reported, including advanced age, high-risk surgery, perioperative hemorrhage, a history of ischemic heart disease, heart failure, cerebrovascular disease, diabetes mellitus requiring insulin, and preoperative serum creatinine of >2.0 mg/dL.[12–14] Identifying at-risk patients and counseling them about potential cardiac complications is essential for informed consent and for minimizing their occurrence. Numerous studies have investigated the perioperative complications of lumbar surgical procedures.[6–8,10,15,16] Smith et al[17,18] used the Scoliosis Research Society Morbidity and Mortality database to study the risks for thromboembolism and wound infections. However, no study has focused on characterizing cardiac risk factors in lumbar spine surgery on a national scale.

The objective of this study is to use the Nationwide Inpatient Sample (NIS) database to identify the national incidence of cardiac complications associated with lumbar fusion (LF) and lumbar decompression (LD) without fusion. We hypothesize that independent risk factors for cardiac events can be detected, that LF patients are at greater risk than LD patients, and that the presence of a cardiac event leads to adverse outcomes, including length of stay (LOS), cost, and mortality.

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