Caroline Helwick

May 01, 2013

New Orleans, Louisiana — According to an analysis of a national database of patients undergoing resection for acoustic neuromas, patients with neurofibromatosis type 2 (NF2) had a 220% increased risk for facial nerve dysfunction after surgery.

"In addition, we found that facial nerve dysfunction was associated with $7000 of increased hospital charges and an extra inpatient day," said Jacob H. Bagley, BS, a medical student at Duke University School of Medicine, Durham, North Carolina, where the study was conducted. The study's senior author was Shivanand P. Lad, MD, PhD.

They reported their findings at the American Association of Neurological Surgeons (AANS) 81st Annual Scientific Meeting.

Predictors of Facial Weakness Identified

The Duke investigators analyzed the Nationwide Inpatient Sample (NIS) to gain insight into the ways that neurosurgeons are treating acoustic neuromas and to determine predictors of facial nerve dysfunction after resection. They also evaluated the effect that operative complications have on discharge status and healthcare resource utilization.

"There are a number of management strategies for acoustic neuromas, and each treatment has a unique risk profile and provides a different degree of tumor mass reduction," Bagley noted. "While microsurgical resection has the best opportunity for complete reduction in tumor mass, it is associated with greater morbidity."

A recent meta-analysis of 79 studies involving almost 12,000 patients found that facial nerve preservation was highest when the middle fossa approach was used (85%), when tumor size was less than 2 cm (90%), and when patients were older than 65 years of age (84%). Other factors have also been associated, including surgeon experience, NF2 status, and preoperative weakness.

Use of the NIS allowed the investigators "to obtain data from a real-world setting," he said. The database is a stratified random sample representing 20% of the nation's hospitals. It contains the International Classification of Diseases, Ninth Revision (ICD-9), diagnosis codes; procedure codes; and charges associated with a single hospital stay. "Using the years 1998 to 2006, we retained every hospital stay in which a patient received an acoustic neuroma resection," Bagley noted.

Facial nerve dysfunction was indicated by the presence of certain ICD-9 codes, such as "injury to facial nerve" and "other disorders of eyelid function." All charges were changed to 2006 dollar values using the inflation of the medical component of the consumer price index.

The study identified 4821 patients. Their median age was 50 years, 83% were white, 75% had private insurance or health maintenance organization coverage, and more than 90% were treated at a teaching hospital. NF2 status was recorded in 3.3% of the cohort.

Facial nerve complications were reported in 15.14% of patients and deaths in 0.33%. The significant predictors of facial nerve dysfunction were nonwhite race, Medicaid pay status (vs all other insurance), and NF2 status.

Table. Predictors of Facial Dysfunction After Acoustic Neuroma Resection

Factor No Facial Nerve Complication (n = 4091) With Facial Nerve Complication (n = 730) Adjusted Odds Ratio and P Value
Median age (y) 50 50
Women (%) 53.1 53.8
Nonwhite (%) 16.2 20.3 1.31 (P < .03)
Medicaid (vs other insurance) (%) 3.9 5.7
NF2 (%) 2.9 5.7 2.27 (P = .0001)
Comorbid conditions (%)      
  0 58.7 56.3
  1 27.3 26.8
  ≥2 13.9 16.8
Teaching hospital (%) 90.2 91.3
Hospital size (%)    
  Large 76.1 72.5
  Medium 19.5 23.6
  Small 4.8 3.9

 

The researchers also evaluated non–facial nerve complications and found these to be significantly higher in Medicaid patients (odds ratio [OR], 1.93; P < .0001), patients with NF2 (OR, 1.84; P = .0001), and patients with at least 2 comorbid conditions (OR vs patients with no comorbidity, 1.31; P < .01).

Patients experiencing a facial nerve complication stayed in the hospital an average of 1 day longer than those without (5 days vs 4 days) and accumulated $7000 in additional charges ($53,679 vs $46,992 in 2006 US dollars). They were also almost twice as likely to have nonroutine discharge (17% vs 9%).

Non–facial nerve complications were also very costly; when the number of complications rose from 2 to 3, hospital charges increased by approximately $50,000, Bagley reported. "We found a substantial impact on health care resources when there were complications," he commented.

He acknowledged that with a retrospective review, it is difficult to infer causality. The study relied on the accuracy of diagnostic and procedure codes, and the charges varied according to insurance type. The preoperative status of the patients was unknown, as were the severity and permanence of the facial nerve dysfunction and the surgery-specific variables.

Valuable Data

Asked to comment for Medscape Medical News, session moderator Christopher McPherson, MD, director of Surgical Neuro-oncology at the University of Cincinnati Neuroscience Institute in Ohio, said it is valuable to have data from a national database because it helps in counseling patients.

In particular, he was surprised at the magnitude of increased risk for facial dysfunction — 200% — associated with NF2 status, although it is known that these patients are more difficult, he said.

"They have tumors that are more aggressive and that tend to be bilateral, and this is associated with worse outcomes, but the incidence of risk was huge in this study," Dr. McPherson noted.

Unfortunately, he added, little can be done to prevent these complications in this subset. "There has been debate about doing less extensive resection and giving radiation, but these patients tend to be susceptible to the risks of radiation, so it's tough," he said. "The main thing is using the data to counsel them about the increased risk."

Mr. Bagley and Dr. McPherson have disclosed no relevant financial relationships.

American Association of Neurological Surgeons (AANS) 81st Annual Meeting: Abstract 736. Presented April 30, 2013.

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