Validation of an International Classification of Diseases, Ninth Revision Code Algorithm for Identifying Chiari Malformation Type 1 Surgery in Adults

Chiari I malformation management in patients with heritable connective tissue disorders

Background

Chiari malformation type I (CMI) is relatively common neurosurgical condition typically treated with posterior fossa decompression. However, the management of CMI in patients with heritable connective tissue disorders (CTDs), such as Ehlers-Danlos Syndrome, Marfan Syndrome, or Osteogenesis Imperfecta, involves a unique set of perioperative challenges.

Objective

This study aims to define the demographic information, comorbidities, and perioperative course of patients with concomitant CMI and CTD.

Methods

Patients with CMI admitted for surgical decompression from 2008 to 2015 were captured using the National Inpatient Sample (NIS). Information was collected based on ICD-9 codes. Descriptive and regression analyses were performed in SPSS (version 26).

Results

38,169 CMI patients, 353 of whom had CTD (0.92%), were identified. CMI patients with CTD were more likely to be female (p < 0.001) and present during teenage (p = 0.033) or young adult years (p < 0.001). They had more chronic issues (p < 0.001): systemic comorbidities include postural orthostatic tachycardia syndrome, cardiac dysrhythmias, and gastroparesis (all p < 0.001). CNS comorbidities include migraine, tethered spinal cord, and epilepsy (all p < 0.001). They have increased joint instability (both p < 0.001), as well as craniocervical instability (CCI). More posterior cervical fusion surgeries and application of cervical halo devices were seen during the same inpatient stay (both p < 0.001).

Conclusions

Patients with concurrent CTD and CMI were more likely to present with complex Chiari and associated CCI. They were also younger, more often female, and had more systemic, CNS, and joint abnormalities. As such, preoperative recognition of an underlying CTD is imperative to achieve optimal outcomes in this patient population.

Inpatient outcomes of posterior fossa decompression with or without duraplasty for Chiari malformation type I

OBJECTIVE

Chiari malformation type 1 (CM-1) is a congenital neurologic condition in which the cerebellar tonsils herniate below the foramen magnum, resulting in symptoms such as headache and neck pain. Two common surgical treatment approaches are posterior fossa decompression with (PFDD) and without duraplasty (PFD). Previous single-center studies have demonstrated increased neurologic complications after PFDD compared to PFD. The goal of this study is to determine differences in inpatient complications and hospitalization data among patients treated with these surgical techniques using a nationwide sample.

METHODS

The National Inpatient Sample (NIS) was queried for years 2012-2015 for all patients with a primary diagnosis of CM-1 who underwent PFD or PFDD. Differences in baseline demographics and comorbidities were accounted for in subsequent analysis using propensity score matching. Hospitalization measures and inpatient complications of the two cohorts were compared using Chi-squared tests and t-tests when appropriate.

RESULTS

A total of 2395 patients with CM-1 were included in this study, with 750 (31.3%) undergoing PFD and 1645 (68.7%) undergoing PFDD. PFDD was associated with higher total hospital costs than PFD. There were no significant differences in other hospitalization or discharge data, non-neurologic complications, or CNS complications (CSF leak, pseudomeningocele, abscess, meningitis, stroke) between the two surgical groups.

CONCLUSIONS

This study represents the largest national analysis to date of adult CM-1 patients undergoing PFD or PFDD. Our findings suggest that whether the decision is made to perform the less invasive PFD or more invasive PFDD, inpatient complications and hospitalization data will not significantly differ.

Outcomes and resource utilization in surgery for Chiari I malformation in a national network of children's hospitals

INTRODUCTION

Chiari malformation type 1 (CM-1) is a common congenital or acquired malformation of the posterior fossa. We aimed to characterize preoperative risk factors, perioperative complications, and postoperative outcomes related to CM-1 surgery in pediatric populations across a nationwide network of pediatric hospitals in the United States (US).

METHODS

The Children's Hospital Association's Pediatric Health Information System (PHIS) database was used to examine patients < 21 years old in the US-based nationwide database who underwent inpatient surgery for CM-1 from 2007 to 2015. Data analyzed included patient characteristics, preoperative comorbidities, perioperative outcomes, short-term postoperative surgical and medical complications, and healthcare resource utilization.

RESULTS

Among the 5976 patients identified, those age 0-4 years had higher medical and surgical complication rates compared to older patients. Those with pre-existing comorbidity of hydrocephalus had higher odds of 30- and 90-day medical and surgical complications. Those with any complications at 90 days had an increased length of stay and higher healthcare costs compared to those without complications. 6.88% of complications were surgical and 1.67% medical. Patients with medical complications had the longer mean stay and associated costs compared to those with surgical complications (13 vs. 6.9 at 95% CI, and $71,300-94,500 vs. $110,400-195,000 at 95% CI).

CONCLUSIONS

Use of a US-based national children's hospital database presents outcomes and resource utilization from a multi-institutional, real-world experience in pediatric hospitals. There was a higher risk of perioperative complications in younger patients and those with pre-existing comorbidities, namely hydrocephalus. Understanding preoperative risk factors, perioperative complications, and postoperative outcomes, as well as healthcare utilization and costs, can help target areas for improvement and guide preoperative counseling and risk stratification.

Trends in surgical treatment of Chiari malformation Type I in the United States

OBJECTIVE The goal of this analysis was to define temporal and geographic trends in the surgical treatment of Chiari malformation Type I (CM-I) in a large, privately insured health care network. METHODS The authors examined de-identified insurance claims data from a large, privately insured health care network of over 58 million beneficiaries throughout the United States for the period between 2001 and 2014 for all patients undergoing surgical treatment of CM-I. Using a combination of International Classification of Diseases (ICD) diagnosis codes and Current Procedural Terminology (CPT) codes, the authors identified CM-I and associated diagnoses and procedures over a 14-year period, highlighting temporal and geographic trends in the performance of CM-I decompression (CMD) surgery as well as commonly associated procedures. RESULTS There were 2434 surgical procedures performed for CMD among the beneficiaries during the 14-year interval; 34% were performed in patients younger than 20 years of age. The rate of CMD increased 51% from the first half to the second half of the study period among younger patients (p < 0.001) and increased 28% among adult patients between 20 and 65 years of age (p < 0.001). A large sex difference was noted among adult patients; 78% of adult patients undergoing CMD were female compared with only 53% of the children. Pediatric patients undergoing CMD were more likely to be white with a higher household net worth. Regional variability was identified among rates of CMD as well. The average annual rate of surgery ranged from 0.8 surgeries per 100,000 insured person-years in the Pacific census division to 2.0 surgeries per 100,000 insured person-years in the East South Central census division. CONCLUSIONS Analysis of a large nationwide health care network showed recently increasing rates of CMD in children and adults over the past 14 years.

Hospitalization Cost Model of Pediatric Surgical Treatment of Chiari Type 1 Malformation

OBJECTIVES

To develop a cost model for hospitalization costs of surgery among children with Chiari malformation type 1 (CM-1) and to examine risk factors for increased costs.

STUDY DESIGN

Data were extracted from the US National Healthcare Cost and Utilization Project 2009 Kids' Inpatient Database. The study cohort was comprised of patients aged 0-20 years who underwent CM-1 surgery. Patient charges were converted to costs by cost-to-charge ratios. Simple and multivariable generalized linear models were used to construct cost models and to determine factors associated with increased hospital costs of CM-1 surgery.

RESULTS

A total of 1075 patients were included. Median age was 11 years (IQR 5-16 years). Payers included public (32.9%) and private (61.5%) insurers. Median wage-adjusted cost and length-of-stay for CM-1 surgery were US $13 598 (IQR $10 475-$18 266) and 3 days (IQR 3-4 days). Higher costs were found at freestanding children's hospitals: average incremental-increased cost (AIIC) was US $5155 (95% CI $2067-$8749). Factors most associated with increased hospitalization costs were patients with device-dependent complex chronic conditions (AIIC $20 617, 95% CI $13 721-$29 026) and medical complications (AIIC $13 632, 95% CI $7163-$21 845). Neurologic and neuromuscular, metabolic, gastrointestinal, and other congenital genetic defect complex chronic conditions were also associated with higher hospital costs.

CONCLUSIONS

This study examined cost drivers for surgery for CM-1; the results may serve as a starting point in informing the development of financial risk models, such as bundled payments or prospective payment systems for these procedures. Beyond financial implications, the study identified specific risk factors associated with increased costs.

Variability in Standard Outcomes of Posterior Lumbar Fusion Determined by National Databases

OBJECTIVE

National databases are used with increasing frequency in spine surgery literature to evaluate patient outcomes. The differences between individual databases in relationship to outcomes of lumbar fusion are not known. We evaluated the variability in standard outcomes of posterior lumbar fusion between the University HealthSystem Consortium (UHC) database and the Healthcare Cost and Utilization Project National Inpatient Sample (NIS).

METHODS

NIS and UHC databases were queried for all posterior lumbar fusions (International Classification of Diseases, Ninth Revision code 81.07) performed in 2012. Patient demographics, comorbidities (including obesity), length of stay (LOS), in-hospital mortality, and complications such as urinary tract infection, deep venous thrombosis, pulmonary embolism, myocardial infarction, durotomy, and surgical site infection were collected using specific International Classification of Diseases, Ninth Revision codes.

RESULTS

Analysis included 21,470 patients from the NIS database and 14,898 patients from the UHC database. Demographic data were not significantly different between databases. Obesity was more prevalent in UHC (P = 0.001). Mean LOS was 3.8 days in NIS and 4.55 in UHC (P < 0.0001). Complications were significantly higher in UHC, including urinary tract infection, deep venous thrombosis, pulmonary embolism, myocardial infarction, surgical site infection, and durotomy. In-hospital mortality was similar between databases.

CONCLUSIONS

NIS and UHC databases had similar demographic patient populations undergoing posterior lumbar fusion. However, the UHC database reported significantly higher complication rate and longer LOS. This difference may reflect academic institutions treating higher-risk patients; however, a definitive reason for the variability between databases is unknown. The inability to precisely determine the basis of the variability between databases highlights the limitations of using administrative databases for spinal outcome analysis.

Complications after craniosynostosis surgery: comparison of the 2012 Kids' Inpatient Database and Pediatric NSQIP Database

OBJECT Research conducted using large administrative data sets has increased in recent decades, but reports on the fidelity and reliability of such data have been mixed. The goal of this project was to compare data from a large, administrative claims data set with a quality improvement registry in order to ascertain similarities and differences in content. METHODS Data on children younger than 12 months with nonsyndromic craniosynostosis who underwent surgery in 2012 were queried in both the Kids' Inpatient Database (KID) and the American College of Surgeons Pediatric National Surgical Quality Improvement Program (Peds NSQIP). Data from published clinical craniosynostosis surgery series are reported for comparison. RESULTS Among patients younger than 12 months of age, a total of 1765 admissions were identified in KID and 391 in Peds NSQIP in 2012. Only nonsyndromic patients were included. The mean length of stay was 3.2 days in KID and 4 days in Peds NSQIP. The rates of cardiac events (0.5% in KID, 0.3% in Peds NSQIP, and 0.4%-2.2% in the literature), stroke/intracranial bleeds (0.4% in KID, 0.5% in Peds NSQIP, and 0.3%-1.2% in the literature), infection (0.2% in KID, 0.8% in Peds NSQIP, and 0%-8% in the literature), wound disruption (0.2% in KID, 0.5% in Peds NSQIP, 0%-4% in the literature), and seizures (0.7% in KID, 0.8% in Peds NSQIP, 0%-0.8% in the literature) were low and similar between the 2 data sets. The reported rates of blood transfusion (36% in KID, 64% in Peds NSQIP, and 1.7%-100% in the literature) varied between the 2 data sets. CONCLUSIONS Both the KID and Peds NSQIP databases provide large samples of surgical patients, with more cases reported in KID. The rates of complications studied were similar between the 2 data sets, with the exception of blood transfusion events where the retrospective chart review process of Peds NSQIP captured almost double the rate reported in KID.

Chiari malformation Type I surgery in pediatric patients. Part 1: validation of an ICD-9-CM code search algorithm

OBJECTIVE Administrative billing data may facilitate large-scale assessments of treatment outcomes for pediatric Chiari malformation Type I (CM-I). Validated International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) code algorithms for identifying CM-I surgery are critical prerequisites for such studies but are currently only available for adults. The objective of this study was to validate two ICD-9-CM code algorithms using hospital billing data to identify pediatric patients undergoing CM-I decompression surgery. METHODS The authors retrospectively analyzed the validity of two ICD-9-CM code algorithms for identifying pediatric CM-I decompression surgery performed at 3 academic medical centers between 2001 and 2013. Algorithm 1 included any discharge diagnosis code of 348.4 (CM-I), as well as a procedure code of 01.24 (cranial decompression) or 03.09 (spinal decompression or laminectomy). Algorithm 2 restricted this group to the subset of patients with a primary discharge diagnosis of 348.4. The positive predictive value (PPV) and sensitivity of each algorithm were calculated. RESULTS Among 625 first-time admissions identified by Algorithm 1, the overall PPV for CM-I decompression was 92%. Among the 581 admissions identified by Algorithm 2, the PPV was 97%. The PPV for Algorithm 1 was lower in one center (84%) compared with the other centers (93%-94%), whereas the PPV of Algorithm 2 remained high (96%-98%) across all subgroups. The sensitivity of Algorithms 1 (91%) and 2 (89%) was very good and remained so across subgroups (82%-97%). CONCLUSIONS An ICD-9-CM algorithm requiring a primary diagnosis of CM-I has excellent PPV and very good sensitivity for identifying CM-I decompression surgery in pediatric patients. These results establish a basis for utilizing administrative billing data to assess pediatric CM-I treatment outcomes.

Complications and Resource Use Associated With Surgery for Chiari Malformation Type 1 in Adults: A Population Perspective

BACKGROUND

Outcomes research on Chiari malformation type 1 (CM-1) is impeded by a reliance on small, single-center cohorts.

OBJECTIVE

To study the complications and resource use associated with adult CM-1 surgery using administrative data.

METHODS

We used a recently validated International Classification of Diseases, Ninth Revision, Clinical Modification code algorithm to retrospectively study adult CM-1 surgeries from 2004 to 2010 in California, Florida, and New York using State Inpatient Databases. Outcomes included complications and resource use 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 1947 CM-1 operations. Surgical complications were more common than medical complications at both 30 days (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 male patients (OR = 3.19). Risk-adjusted hospital costs were $22530 at 30 days and $24852 at 90 days postoperatively. Risk-adjusted 90-day costs were more than twice as high for patients experiencing surgical ($46264) or medical ($65679) complications than for patients without complications ($18880).

CONCLUSION

Complications after CM-1 surgery are common, and surgical complications are more frequent than medical complications. 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.