Friday, September 28, 2018 4:05 PM–5:05 PM abstracts: cervical myelopathy and deformity: 253. Degenerative cervical myelopathy in the United States, 2002-2014: a silent epidemic

Abstract

BACKGROUND CONTEXT Degenerative cervical myelopathy (DCM) is the leading cause of spinal cord injury and a major source of disability globally; however, data on the national trends of DCM incidence are limited. PURPOSE To evaluate contemporary trends in DCM incidence and healthcare resource utilization in the United States. STUDY DESIGN/SETTING Determination of epidemiological estimates of DCM using population-based survey data from the United States AHRQ HCUP National Inpatient Sample (NIS) for years 2002 through 2014. PATIENT SAMPLE A total of 618,323 patients who underwent surgery for DCM in the United States between 2002 and 2014. OUTCOME MEASURES Overall and age- and sex-stratified incidences of surgically-treated DCM; surgical techniques utilized, hospitalization charges and costs, and inpatient complications and mortality for treatment of DCM. METHODS Patients who underwent surgery for DCM were identified from the NIS using ICD-9-CM codes based on a diagnosis code for cervical spondylosis and/or OPLL plus cervical myelopathy, plus a procedure code for anterior or posterior decompression plus or minus fusion, or disc replacement. Data pertaining to patient-, treatment-, admission-, and hospital-related factors and outcomes were collected. Patient-specific discharge weights were used to obtain national estimates. We calculated standard errors and 95% confidence intervals (CIs) using strata and cluster variables to account for hospital-level clustering of patients and the sampling design. We calculated overall and age- and sex-stratified incidences of surgically-treated DCM per 100,000 persons for each year using population estimates from the U.S. Census Bureau. These were compared to incidences of acute traumatic SCI and three very common neurosurgical procedures: (1) evacuation of subdural hematoma (SDH) (including acute, subacute, and chronic); (2) craniotomy for tumor (including primary and metastatic); and (3) clipping or endovascular coiling of cerebral aneurysm. Hospitalization charges and costs were indexed to year 2008 to adjust for inflation using Consumer Price Index (CPI) data from the U.S. Bureau of Labor Statistics. Trends were analyzed by joinpoint regression analysis for incidences to determine the average annual percent change (AAPC), the Cochrane–Armitage trend test for categorical variables, and linear regression for continuous variables. RESULTS The overall incidence of surgical DCM rose from 10.3 per 100,000 persons in 2002 to 21.1 per 100,000 persons in 2014, representing an AAPC of 5.9% (95% CI 5.5%–6.3%). The highest incidence (61.1/100,000) and growth rate (AAPC 7.4%) were seen in the 65 to 84-year-old age group. Age-adjusted incidence and annual growth rates for DCM exceeded those of acute traumatic SCI (5.0/100,000; −0.5%), evacuation of SDH (8.2/100,000; 0.4%), craniotomy for brain tumor (14.2/100,000; 1.1%), and clipping or coiling of cerebral aneurysm (7.2/100,000; 2.4%). Cumulative hospital charges and costs for DCM rose from $0.99 billion and $0.29 billion in 2002 to $5.13 billion and $1.32 billion in 2014, respectively. The proportion of cases for which Medicare was the primary payer increased from 30.5% in 2002 to 43.6% in 2014. CONCLUSIONS DCM is the leading indication for operation on the central nervous system. The incidence of, and healthcare dollars spent on, surgery for DCM has steadily risen over the past decade likely owing both to an aging population and increasing recognition of the role of surgical management in these patients.