Abstract
Study Design:
Retrospective Cohort Study
Objective:
We aimed to characterize the treatment patterns and the associated costs in patients with CSF leak after spine procedures in the United States.
Background:
Cerebrospinal fluid (CSF) leak is a common complication after spinal procedures. However, there is little data regarding the national patterns of treatment choice and the associated healthcare resource utilization (HCRU).
Methods:
We utilized the IBM MarketScan Research databases to retrospectively analyze adult US patients diagnosed with CSF leak within 30 days of spine procedures between 2001 and 2018. Treatment prevalence, treatment failure, and HCRU data within 30 days of the CSF leak were collected. A sub-analysis was performed on patients who received epidural blood patches (EBP) to better understand healthcare utilization attributable to this treatment modality.
Results:
21,414 patients were identified. The most common causes of CSF leak were diagnostic spinal tap (59.2%) and laminectomy/discectomy (18.7%). With regard to treatment prevalence, 40.4% of the patients (n=8651) had conservative medical management, 46.6% (n=9987) received epidural blood patch repair, 9.6% required surgical repair (n=2066), and 3.3% (n=710) had lumbar drain/puncture. 967 (9.7%), 150 (21.1%), and 280 (13.5%) patients failed initial EBP, lumbar drain, and surgery, respectively, and the overall failure rate was 10.9% (n=1397).
The median 30-day total cost across all groups was $5,101. Patients who received lumbar drain ($22,341) and surgical repair ($30,199) had higher 30-day median total costs than EBP ($8,140) or conservative management ($17,012). The median 30-day total cost for patients whose EBP failed ($8,179) was substantially greater than those with a successful EBP repair ($3,439).
Conclusions:
National treatment patterns and costs for CSF leaks were described. When used in the correct patient cohort, EBP has lower failure rates and costs than comparable alternatives. EBP may be considered more often in situations where conservative management or lumbar drains are currently being used.
Keywords: Cerebrospinal fluid leak, healthcare economics, epidural blood patch, treatment pattern
Introduction
Cerebrospinal fluid (CSF) leaks affect between 2 and 20% of patients1 who undergo spinal procedures. Various modalities exist for treating CSF leaks, including conservative medical management without surgical intervention2, epidural blood patching (EBP)3 or injection of fibrin glue4, placement of a lumbar drain5, and direct suturing to close the defect.6,7
Though CSF leaks can occur spontaneously2,8 or iatrogenically after manipulation of the dura mater, postprocedural CSF leaks have been associated with longer hospitalizations and more readmissions, and account for up to 10% of the total costs associated with neurosurgical procedures9,10. Previous studies have reported cost burdens of postoperative CSF leaks between $41,000 and $50,000 per affected patient9,11–13. This increased healthcare resource utilization (HCRU) is important given the increasing scrutiny on medical expenditure in the United States.
Importantly, most previous studies of costs attributable to post-procedural CSF leaks have significant limitations. Most are single-institution analyses, and almost all strictly examine CSF leaks after intracranial procedures. Further, only one study12 compared costs between different treatments for CSF leak, but the only interventions studied were lumbar drain, surgery, or both. Finally, types of costs accounted for and countries of origin are variable. To date, there is no comprehensive examination of costs associated with iatrogenic CSF leak repair in the United States. To close this gap in understanding, we summarize the etiology, treatment paradigms, and cost burden for spinal postprocedural CSF leaks in the United States.
Methods
Data Source
The IBM MarketScan® Research databases, including the Commercial Claims and Encounters, Medicare Supplemental and Coordination of Benefits, and Multi-States Medicaid databases from years 2000 to 2018, were utilized to retrospectively analyze the healthcare resource utilization related to cerebrospinal fluid (CSF) leak repairs in the United States.
Study Design
Procedures and diagnoses were identified using a combination of International Classification of Diseases, Ninth and Tenth Revisions (ICD-9, ICD-10), Current Procedural Terminology (CPT®), and Healthcare Common Procedure Coding System (HCPCS) procedural codes (Supplementary Tables S1–S2). ICD9/10 and CPT codes related to neurological procedures were categorized into “single-level” procedure categories based on the Healthcare Cost and Utilization Project (HCUP) Clinical Classifications Software (CCS) for services and procedures (ref. 23–25). This leads to 10 neurological procedure categories.
Adult patients with a CSF leak diagnosis between 2001 and 2018 and a neurological procedure within 30 days before the CSF leak were identified. The index date was defined as the first date of the CSF leak diagnosis after spine procedures. Additional exclusion criteria were summarized in Figure 1. Patients were divided into four groups based on the initial treatment paradigm for the CSF leak within 30 days of the index date: 1) medical management alone (“conservative,” no codes for CSF leak repair or treatment), 2) lumbar drain, 3) epidural blood patch (“EBP”), 4) surgery. Of note, because of limitations of the database, “conservative” management patients are defined by the absence of relevant procedural codes and are assumed to have been treated with standard of care bedrest and caffeine.
Figure 1:
Consort diagram outlining patient selection. Adult patients with CSF leak diagnosis between 2001 and 2018 were identified. Exclusion criteria were: continuous enrollment less than one year before or 30 days after the index date of CSF leak diagnosis (to avoid bias due to incomplete data); lack of at least one spine surgery, as defined by the HCUP CCS single-level procedure categories, within 30 days of the index date; presence of prior CSF leak or dural tear within one year of the index date; spontaneous CSF leak (code for a CSF leak with no spine surgery within 30 days of the leak); and more than one treatment (lumbar drain, blood patch, or surgery) on the same day. The remaining patients were divided into four groups based on the initial treatment paradigm for the CSF leak within 30 days of the index date: 1) medical management alone (“conservative,” no codes for CSF leak repair or treatment), 2) lumbar drain (“lumbar drain”), 3) epidural blood patch (“EBP”), 4) surgery (“surgery”). For cost analysis, patients with fully or partially capitated health plans were excluded; 1st percentile cost outliers were also excluded to reduce skew.
Outcomes and Objectives
The primary outcomes included the initial treatment options for CSF leaks and subsequent 30-day HCRU for those patients. Since additional costs may be incurred if these initial treatments fail, secondary outcomes included the initial treatment failure rate and the subsequent salvage therapy. The initial treatment was deemed to have failed if patients had a subsequent blood patch, lumbar drain, or surgery within 30 days of the diagnosis of CSF leak.
Statistical Analysis
Among patients who had EBP as the initial treatment, multivariable logistic regression was fit to examine the association of age at diagnosis, insurance, sex, Elixhauser score, having laminectomy, diagnostic spinal tap, and insertion of a catheter or spinal stimulator performed within 30 days before the index date, with EBP failure. All analyses were conducted using SAS 9.4 (SAS Institute Inc., Cary, NC). All statistical tests were two-sided, with the level of significance at 0.05.
Results
Patient Characteristics
A total of 352,375 patients diagnosed with CSF leak between 2001 and 2018 were identified. After applying inclusion/exclusion criteria (Figure 1), 21,414 adult patients with CSF leak after spine procedures were analyzed. Patients were then assigned to four groups based on the initial treatment for their CSF leak. Of those, 9,987 (46.6%) patients underwent EBP, 8,651 (40.4%) underwent conservative medical management, 2,066 (9.6%) underwent surgical correction, and 710 (3.3%) had lumbar drain placement. Demographic information stratified by the initial treatments is summarized in Table 1a. The top 3 spine procedures performed before index CSF leak for each treatment group are summarized in Table 1b.
Table 1a.
Demographic information for patients with postprocedural CSF leaks
| Conservative (N=8651) | Lumbar Drain (N=710) | Blood Patch (N=9987) | Surgery (N=2066) | Total (N=21414) | |
|---|---|---|---|---|---|
|
| |||||
| Age at Diagnosis | |||||
| Median (Q1, Q3) | 46 (34, 57) | 52 (42, 61) | 41 (32, 50) | 54 (44, 62) | 44 (34, 55) |
| Range | (18, 95) | (18, 95) | (18, 89) | (18, 91) | (18, 95) |
| Inpatient/outpatient at Diagnosis | |||||
| Inpatient | 3303 (38.2%) | 536 (75.5%) | 1172 (11.7%) | 1479 (71.6%) | 6490 (30.3%) |
| Outpatient | 5348 (61.8%) | 174 (24.5%) | 8815 (88.3%) | 587 (28.4%) | 14924 (69.7%) |
| Sex | |||||
| Male | 2911 (33.6%) | 322 (45.4%) | 2361 (23.6%) | 1045 (50.6%) | 6639 (31.0%) |
| Female | 5740 (66.4%) | 388 (54.6%) | 7626 (76.4%) | 1021 (49.4%) | 14775 (69.0%) |
| Elixhauser Mortality Score * | |||||
| Median (Q1, Q3) | 0 (−1, 7) | 0 (−1, 11) | 0 (−1, 5) | 0 (−1, 5) | 0 (−1, 6) |
| Range | (−26.0, 74.0) | (−23.0, 52.0) | (−23.0, 62.0) | (−20.0, 43.0) | (−26.0, 74.0) |
Claims within 12 months before the index dates were used to identify Elixhauser comorbidities. The ICD9/10 diagnosis codes for Elixhauser comorbidities can be found on the HCUP website.26
Table 1b.
Top 3 Neurological procedures performed 30 days before CSF leak (CCS single level category)
| Conservative (N=8651) | Lumbar Drain (N=710) | Blood Patch (N=9987) | Surgery (N=2066) | Total (N=21414) | |
|---|---|---|---|---|---|
|
| |||||
| CCS-4: Diagnostic spinal tap | 4586 (53.0%) | 205 (28.9%) | 7814 (78.2%) | 82 (4.0%) | 12687 (59.2%) |
| CCS-3: Surgery (Laminectomy; excision intervertebral disc) | 1751 (20.2%) | 334 (47.0%) | 406 (4.1%) | 1521 (73.6%) | 4012 (18.7%) |
| CCS-5: Insertion of catheter or spinal stimulator and/or injection into spinal canal | 1429 (16.5%) | 38 (5.4%) | 1531 (15.3%) | 262 (12.7%) | 3260 (15.2%) |
Impact of Initial Treatment on Healthcare Resource Utilization
Inpatient, outpatient, medication, and total costs within 30 days of CSF leak diagnosis for each group are presented in Table 2. The median total cost across all groups was $5,101, with patients who received lumbar drain ($22,341) and surgery ($21,037) having higher median total costs than those receiving EBP ($3,670) or conservative management ($6,119). The median LOS of patients receiving lumbar drain and surgery was 7 days and 4 days, respectively, whereas patients receiving EBP and conservative management both had a median length of stay of 0 days.
Table 2.
30-day cost after diagnosis of CSF leaks
| Conservative (N=5352) | Lumbar Drain (N=469) | Blood Patch (N=6810) | Surgery (N=1382) | Total (N=14013) | |
|---|---|---|---|---|---|
|
| |||||
| Inpatient Service Cost | |||||
| Mean (SD) | 11974 (24172) | 26724 (32692) | 2862 (11153) | 23713 (28418) | 9197 (21269) |
| Median (Q1, Q3) | 0 (0, 13859) | 15960 (1435, 36832) | 0 (0, 0) | 15556 (2169, 33718) | 0 (0, 7697) |
| Outpatient Service Cost | |||||
| Mean (SD) | 4520 (8123) | 4560 (8461) | 4755 (7715) | 6062 (11825) | 4788 (8395) |
| Median (Q1, Q3) | 2045 (758, 4798) | 1583 (400, 5237) | 2684 (1422, 5056) | 2133 (435, 6214) | 2403 (1029, 5070) |
| Medication Cost | |||||
| Mean (SD) | 518 (1478) | 409 (1293) | 523 (1511) | 424 (1143) | 508 (1459) |
| Median (Q1, Q3) | 123 (21, 460) | 99 (14, 360) | 106 (14, 417) | 127 (23, 409) | 115 (18, 428) |
| Total Cost | |||||
| Mean (SD) | 17012 (25699) | 31693 (33339) | 8140 (14134) | 30199 (29632) | 14492 (23005) |
| Median (Q1, Q3) | 6119 (2148, 20595) | 22341 (6603, 42800) | 3670 (1977, 7823) | 21037 (9444, 39972) | 5101 (2231, 16292) |
All costs were adjusted for inflation based on US Bureau of Labor Statistics indices to 2019 USD. Costs above the 99th percentile were removed from the summary.
Rates of Treatment Failure
The overall failure rate for all patients was 10.9% (n=1397). Specifically, EBP had a failure rate of 9.7% (n=967), which was lower compared to lumbar drain (21.1%, n=150) and surgery (13.5%, n=280). Of those who failed EBP, most patients (83.4%, n=806) underwent additional EBP. These data are summarized in Table 3.
Table 3.
Salvage therapy after initial treatment
| Blood Patch (N=9987) | Lumbar Drain (N=710) | Surgery Group (N=2066) | Total (N=12763) | |
|---|---|---|---|---|
|
| ||||
| Failed initial treatment | ||||
| No | 9020 (90.3%) | 560 (78.9%) | 1786 (86.5%) | 11366 (89.1%) |
| Yes | 967 (9.7%) | 150 (21.1%) | 280 (13.5%) | 1397 (10.9%) |
|
| ||||
| Salvage therapy | ||||
| Blood patch | 806 (83.4%) | 17 (11.3%) | 17 (6.1%) | 840 (60.1%) |
| Lumbar drain | 35 (3.6%) | 48 (32%) | 53 (18.9%) | 136 (9.7%) |
| Surgery | 90 (9.3%) | 57 (38%) | 160 (57.1%) | 307 (22%) |
| ≥ 2 additional treatments | 36 (3.7%) | 28 (18.7%) | 50 (17.9%) | 114 (8.2%) |
Patients with conservative management were not included in this table because by default these patients had no other treatments within 30 days of the initial treatment.
Risk Factors and HCRU Associated with EBP Failure
As shown in Table 4, multivariable logistic regression analysis shows that the odds of having EBP failure for patients who had prior laminectomy are 2.8 times that of those who did not, and the odds of having EBP failure for patients who had diagnostic spinal tap are 0.41 times that of those who did not.
Table 4.
Multivariable logistic regression analysis on EBP failure among patients with EBP as the initial treatment
| EBP failure - No (N=9020) | EBP failure -Yes (N=967) | AOR [95% CI] | p-value | |
|---|---|---|---|---|
| Age [Median (Q1, Q3)] | 41 (32, 50) | 42 (33, 50) | 0.991 [0.99, 1.00] | 0.02 |
| Insurance | ||||
| Medicaid | 1302 (14.4%) | 133 (13.8%) | 1.02 [0.84, 1.24] | 0.83 |
| Medicare | 227 (2.5%) | 34 (3.5%) | 1.12 [0.74, 1.71] | 0.59 |
| Commercial | 7491 (83.0%) | 800 (82.7%) | reference | |
| Sex: | ||||
| Female | 2076 (23.0%) | 285 (29.5%) | 0.87 [0.74, 1.01] | 0.07 |
| Male | 6944 (77.0%) | 682 (70.5%) | reference | |
| Elixhauser mortality score [Median (Q1, Q3)] | 0 (−1, 5) | 0 (−2, 5) | 1.002 [0.99, 1.01] | 0.86 |
| CCS-3: Laminectomy; excision intervertebral disc | ||||
| Yes | 8748 (97%) | 833 (86.1%) | 2.80 [2.07, 3.79] | <0.001 |
| No | 272 (3%) | 134 (13.9%) | reference | |
| CCS-4: Diagnostic spinal tap | ||||
| Yes | 1784 (19.8%) | 389 (40.2%) | 0.41 [0.31, 0.53] | <0.001 |
| No | 7236 (80.2%) | 578 (59.8%) | reference | |
| CCS-5: Insertion of catheter or spinal stimulator and injection into spinal canal | ||||
| Yes | 7705 (85.4%) | 751 (77.7%) | 0.88 [0.67, 1.16] | 0.38 |
| No | 1315 (14.6%) | 216 (22.3%) | reference | |
Odd ratio with 1-year increase of age at diagnosis
Odds ratio with 1-unit increase of Elixhauser mortality score
Sample size n=9987
Thirty-day costs stratified by initial EBP failure are presented in Table 5. Patients failing EBP incurred higher median outpatient service costs ($4413 vs. $2559) and median total costs ($8179 vs. $3439) (Table 5).
Table 5.
30-day cost stratified by EBP failure among patients with EBP as the initial treatment
| EBP Failure | |||
|---|---|---|---|
| No (N=6168) | Yes (N=642) | Total (N=6810) | |
|
| |||
| Inpatient Service Cost | |||
| Mean (SD) | 2271 (9686) | 8538 (19575) | 2862 (11153) |
| Median (Q1, Q3) | 0 (0, 0) | 0 (0, 8220) | 0 (0, 0) |
| Outpatient Service Cost | |||
| Mean (SD) | 4513 (7574) | 7081 (8619) | 4755 (7715) |
| Median (Q1, Q3) | 2559 (1371, 4720) | 4413 (2435, 8449) | 2684 (1422, 5056) |
| Medication Cost | |||
| Mean (SD) | 519 (1457) | 562 (1957) | 523.3 (1511) |
| Median (Q1, Q3) | 104 (14, 418) | 130 (20, 404) | 106 (14, 417) |
| Total Cost | |||
| Mean (SD) | 7303 (12895) | 16181 (21232) | 8140 (14134) |
| Median (Q1, Q3) | 3439 (1880, 6984) | 8179 (3945, 19561) | 3670 (1977, 7823) |
All costs were adjusted for inflation based on US Bureau of Labor Statistics indices to 2019 USD. Costs above the 99th percentile were removed from the summary.
Discussion
Key Conclusions
In the present study, we perform a large claims-based analysis on the HCRU associated with postprocedural spinal CSF leaks. CSF leak is a common complication of spinal procedures7, and EBP has emerged as an increasingly popular treatment option14. Nevertheless, there is still a dearth of national-level data on the incidence of spinal postprocedural CSF leaks, the etiology of such leaks, and the HCRU related to treatment. We found that iatrogenic CSF leaks after spine procedures are most likely to be treated by EBP in younger patients without a history of invasive surgical procedures near the spine, whereas older, sicker patients who had invasive surgical procedures were more likely to be treated with a lumbar drain or surgical closure of the dural defect. Further, we quantified detailed costs attributable to EBP as a treatment for CSF leaks and assessed rates of EBP failure and associated costs.
Etiology of CSF leak and overview of initial treatment patterns
In our analysis, patients with CSF leak who had preceding lumbar puncture were more likely to be treated initially with blood patching or conservative management, whereas patients who had a preceding laminectomy were more likely to be treated initially with dural repair surgery (Table 1b). Conservative management and EBP have both been used in iatrogenic cases7, while surgical treatment may be preferred when a dural defect can be visualized intraoperatively or with radiologic imaging 1. Thus, the size of the dural defect is important in interpreting these results—iatrogenic leaks due to larger surgeries such as laminectomy may result in larger dural defects which are not amenable to closure by EBP and require definitive surgical management. Accordingly, our multivariate model supported this conclusion, as CSF leaks repaired with EBP were more likely to be successful if the etiology was from a diagnostic spinal tap compared to a laminectomy.
Healthcare Resource Utilization Associated with Initial Treatment
The median LOS was higher for lumbar drain and surgery compared to EBP and conservatively managed patients. This is understandable given that EBP and conservative management are primarily outpatient procedures, whereas lumbar drainage and surgery frequently require hospital admission. Total 30-day direct costs were much lower for patients treated with EBP or conservative management compared to those treated with surgical closure or lumbar drain, and the vast majority of this cost difference could be attributed to increased inpatient service costs (Table 2). Strikingly, total direct costs for EBP were about 60% of those of even conservative management, though this excludes indirect costs such as lost wages. Though others have also suggested that prolonged conservative management is not cost-effective15, we provide a quantification of this difference. Ultimately, EBP was the cheapest, most successful treatment option in appropriate patient cohorts. Future randomized studies will need to be performed to allow for direct head-to-head comparisons of cost-effectiveness.
Salvage therapy and EBP Failure
When stratifying by initial treatment for CSF leak, EBP was the most successful when used in appropriate patients with smaller dural defects. Conversely, larger dural defects may be a driver for the higher failure rates for lumbar drain and surgical treatment. This also may explain why the failure of initial EBP most commonly occurred after more invasive spine procedures and why laminectomy was associated with EBP failure in our regression model. Further, our analysis reveals that physicians are likely to repeat the initial treatment as salvage therapy, showing that considerations for selection of salvage therapy are often similar to those for initial treatment.
In addition to the size of the dural defect4, current literature focusing on predictive factors for EBP success also highlights other factors including the caliber of the needle used to perform preceding lumbar puncture, time delay from CSF leak diagnosis to EBP, volume of blood injected, neuroimaging findings, and neutrophil-to-lymphocyte ratio16–18. Thus, our analysis adds another important consideration when deciding the appropriateness of EBP treatment.
Current literature remains unclear on the best treatment option for iatrogenic spinal CSF leaks. We found that EBP is a common and cost-effective treatment strategy, especially to treat smaller dural defects. However, EBP may not be the first-line treatment in all scenarios and is more successful when the patient’s CSF leak is caused by less invasive procedures such as lumbar punctures. Thus, EBP should be considered more often in situations where conservative management and lumbar drains are currently being used. These principles can be used to improve high-value and cost-effective care.
Supplementary Material
Acknowledgment
We wish to acknowledge support from the Biostatistics, Epidemiology and Research Design (BERD) Methods Core funded through Grant Award Number UL1TR002553 from the National Center for Advancing Translational Sciences (NCATS), a component of the National Institutes of Health (NIH). The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.
Disclosures:
This publication was made possible (in part) by Grant Number UL1TR002553 from the National Center for Advancing Translational Sciences (NCATS) of the National Institutes of Health (NIH), and NIH Roadmap for Medical Research (Drs. Liu and Lee). Its contents are solely the responsibility of the authors and do not necessarily represent the official views of NCATS or NIH.
Footnotes
This study was determined exempt from IRB by the Duke University IRB board.
There are no Conflicts of Interest for any authors.
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