Complications and Resource Utilization Associated with Surgery for Chiari Malformation Type 1 in Adults: A Population Perspective.

Neurosurgery 77:261-8, 2015.

Objective: To study complications and resource utilization associated with adult CM-1 surgery using administrative data.

Methods: We used a recently-validated ICD-9-CM code algorithm to retrospectively study adult CM-1 surgeries from 2004–2010 in California, Florida, and New York using State Inpatient Databases. Outcomes included complications and resource utilization within 30 and 90 days of treatment. We used multivariable-logistic regression to identify risk factors for morbidity and negative binomial models to determine risk-adjusted costs.

Results: We identified 1,947 CM-1 operations. Surgical complications were more common than medical at both 30 (14.3% vs 4.4%) and 90 days (18.7% vs 5.0%) postoperatively. Certain comorbidities were associated with increased morbidity; for example, hydrocephalus increased the risk for surgical (odds ratio [OR]=4.51) and medical (OR=3.98) complications. Medical but not surgical complications were also more common in older patients (OR=5.57 for oldest vs youngest age category) and males (OR=3.19). Risk-adjusted hospital costs were $22,530 at 30 days and $24,852 at 90 days postoperatively. Risk-adjusted 90-day costs were more than twice as high for patients experiencing surgical ($46,264) or medical ($65,679) complications than patients without complications ($18,880).

Conclusion: Complications after CM-1 surgery are common, and surgical complications are more frequent than medical. Certain comorbidities and demographic characteristics are associated with increased risk for complications. Beyond harming patients, complications are also associated with substantially higher hospital costs. These results may help guide patient management and inform decision making for patients considering surgery.

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