
==== Front
Interv Pain Med
Interv Pain Med
Interventional Pain Medicine
2772-5944
Elsevier

S2772-5944(24)00032-3
10.1016/j.inpm.2024.100412
100412
Original Article
Percutaneous image-guided lumbar decompression and outpatient laminectomy for the treatment of lumbar spinal stenosis: a 2-year Medicare claims benchmark study
Staats Peter S. drpeterstaats@gmail.com
a⁎
Dorsi Michael J. sierraspinesociety@gmail.com
b
Reece David E. Docd21@me.com
c
Strand Natalie H. strand.natalie@mayo.edu
d
Poree Lawrence Lawrence.Poree@ucsf.edu
e
Hagedorn Jonathan M. jonhagedornmd@yahoo.com
f
a National Spine and Pain Centers, Atlantic Beach, FL, USA
b UCLA, Westlake Village Primary & Specialty Care, 1250 La Venta Drive, Westlake Village, CA, 91361, USA
c Walter Reed National Military Medical Center, 8901 Wisconsin Ave, Bethesda, MD, 20889, USA
d Anesthesiology and Pain Medicine, Mayo Clinic Arizona, 5777 E. Mayo Blvd, Phoenix, AZ, 85054, USA
e Department of Anesthesia and Perioperative Care, University of California at San Francisco, UCSF Pain Management Center, 2255 Post Street, San Francisco, CA, 94115, USA
f iSpine Pain Physicians, 9645 Grove Circle N, Maple Grove, MN, 55369, USA
⁎ Corresponding author. drpeterstaats@gmail.com
22 4 2024
6 2024
22 4 2024
3 2 10041228 2 2024
2 4 2024
8 4 2024
© 2024 The Authors
2024
https://creativecommons.org/licenses/by/4.0/ This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
Background

This prospective longitudinal study compares outcomes for Medicare beneficiaries receiving outpatient percutaneous image-guided lumbar decompression (PILD) using the mild® procedure to patients undergoing outpatient laminectomy. All patients were diagnosed with lumbar spinal stenosis (LSS) with neurogenic claudication (NC).

Methods

All medical claims for 100 % of Medicare beneficiaries were reviewed, with study subjects identified using Centers for Medicare and Medicaid Research Identifiable Files. Baseline data were extracted individually to allow for longitudinal analysis through two-year follow-up. The index procedure was defined as the first mild or outpatient laminectomy during the enrollment period. The rate of subsequent surgical procedures and incidence of harms were used as study outcomes.

Results

Cohorts included 2197 mild and 7416 laminectomy patients. mild patients were significantly older (76.7 years versus 73.4 years, respectively; p < 0.0001), and 57.4 % of mild were female, compared to 43.3 % of laminectomy (p < 0.0001). mild patients presented with significantly more baseline comorbidities compared to laminectomy patients (mean of 5.7 versus 4.8, respectively; p < 0.0001). Subsequent surgical procedure rate of 9.0 % for mild was significantly higher than 5.5 % for laminectomy (p < 0.0001). mild experienced harms at a significantly lower rate than laminectomy (1.9 % versus 5.8 %, respectively; p < 0.0001). The composite rate of subsequent surgical procedures and harms was similar between groups at 10.8 % for mild and 11.0 % for laminectomy.

Conclusions

mild can be considered a viable option for treatment of LSS with NC as evidenced by real-world data in this study. At two-years, mild patients experienced fewer harms and underwent more subsequent surgical procedures than laminectomy patients. The higher rate of subsequent surgical procedures for mild may be attributable to its position earlier in the LSS treatment algorithm. The overall rate of harms and subsequent surgical procedures was similar between groups, suggesting that mild should be considered as a treatment option, particularly for older patients with multiple comorbidities.

Keywords

Lumbar spinal stenosis
Neurogenic claudication
mild
Outpatient laminectomy
Medicare claims
Percutaneous image-guided lumbar decompression
PILD
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pmc1 Introduction

Lumbar spinal stenosis (LSS) is a common degenerative spinal condition that most often impacts the elderly and is associated with chronic pain and reduced mobility [[1], [2], [3]]. Treatment of LSS generally begins with conservative care, followed by non-surgical minimally invasive interventions such as injections and PILD, and then surgery if symptoms persist or recur. An important tenet of treatment plans for any medical condition is that early management involves non-invasive or minimally invasive therapies with lower risk when compared to treatments that are later in the algorithm. This is especially important for patients presenting with high comorbidities or advanced age [4]. It is notable that LSS has been reported to be the most common indication for lumbar spine surgery in older adults [2]. Given the increased risks of open surgery, which is associated with longer recovery times and higher complication rates compared to less invasive procedures, the care continuum for the elderly LSS patient population must be considered [2,4,5].

The percutaneous mild® procedure (Vertos Medical, Aliso Viejo, CA) has been available in the US since 2006 for treatment of LSS with neurogenic claudication (NC) secondary to ligamentum flavum hypertrophy [6]. This procedure has demonstrated significant improvement in mobility and reduction in pain in multiple Level 1 randomized controlled trials (RCTs), and as a minimally invasive option, is positioned early in the LSS treatment algorithm along with epidural steroid injections [3,[7], [8], [9]].

The purpose of this population-based longitudinal study was to compare two-year rates of subsequent surgical procedures and harms for Medicare beneficiaries receiving either mild or outpatient laminectomy for treatment of LSS with NC using Medicare claims data. Although mild and surgical decompression patients may have different treatment indications, the use of claims data allows for the comparison of two procedures that treat LSS but have disparate positions on the treatment algorithm. Outpatient laminectomy was chosen as a comparator to provide a more relevant comparison to the mild procedure which is also outpatient. To validate study methods, outcomes from this study were compared to other published reports of two-year subsequent surgical procedure rates for LSS patients treated with laminectomy using claims data. Importantly, while this analysis focused specifically on patients treated with laminectomy in an outpatient setting, the definition of subsequent surgical procedures and methods used in this report were consistent with that used in these comparative analyses [4,[10], [11], [12], [13], [14], [15]].

2 Materials and methods

2.1 Data source

All medical claims for 100 % of Medicare beneficiaries were reviewed, with study subjects identified using the Centers for Medicare and Medicaid Services (CMS) Research Identifiable Files (RIFs). Eligibility data, baseline characteristics, subsequent surgical procedures, and harms were identified and classified using International Classification of Diseases, Tenth Edition (ICD-10) administrative codes and American Medical Association's (AMA's) Current Procedural Terminology (CPT). All baseline data, including patient history, demographics, and comorbidities were extracted on an individual basis to allow for longitudinal analysis with outcomes. The index procedure was defined as the first mild or outpatient laminectomy procedure for an individual patient during the enrollment period. The study protocol was reviewed by WCG institutional review board (IRB) and determined to be exempt from IRB oversight (Department of Health and Human Services regulations 45 CFR 46).

2.2 Patient selection

All patients with a primary diagnosis of LSS with NC (ICD-10-CM diagnosis code M48.062) and treated with either a mild procedure (CPT code 0275T) or laminectomy (CPT code 63047) during the enrollment period from January 1, 2017 through March 31, 2019 were considered for inclusion. Patients receiving single or multi-level procedures were included. Patients were excluded if they were not enrolled in Medicare for at least 12 months prior to the index procedure, if they were treated with laminectomy, laminotomy, lumbar fusion, interspinous spacer, or mild during the 12 months prior to the index procedure, or if two years of follow-up data was not available. Two-year follow-up was calculated from the date of each index procedure. And finally, patients who were treated in an inpatient setting or unconfirmed place of service were excluded. Patient selection for this study is illustrated in Fig. 1.Fig. 1 Patient selection flow chart.

Fig. 1

2.3 Measures of comorbidity

Baseline comorbidities were identified and compared using 38 Elixhauser conditions refined for ICD-10-CM (v2022.1). In addition, three Clinical Classifications Software Refined for ICD-10-CM Diagnoses for presence of acute myocardial infarction, cardiac dysrhythmias, and fluid and electrolyte disorders were included [16] (see https://www.hcup-us.ahrq.gov/toolssoftware/ccsr/dxccsr.jsp). A search for diagnosis codes occurring during the 12 months prior to index was used to identify patients with these pre-existing comorbidities.

2.4 Outcomes

Rate of subsequent surgical procedures, incidence of harms, and combined rate of subsequent surgical procedures and harms during the two years following the index procedure were used as study outcomes.

2.5 Subsequent surgical procedures

Subsequent surgical procedures were defined as the first lumbar surgery following the index procedure. Multiple subsequent surgical procedures were counted if they occurred on the same day but only one incident was considered when calculating the overall procedure rate. The overall rate is the percent of total patients receiving at least one lumbar surgery after the index. Subsequent surgical procedures included disc procedures, endoscopic decompression, vertebral fusion, laminectomy/laminotomy, and implantation of a spacer with open decompression, and a primary diagnosis code of LSS with NC was required.

2.6 Harms

Harms were identified using diagnosis and procedure codes and confirmed as being associated with the index procedure. Consistent with other open decompression claims publications, all harms, except for heterotopic ossification, were restricted to inpatient claims, including those occurring on the day of index [4,13,15]. Harms categories are defined in Table 1, together with the time period for which harms would be considered. Deaths occurring more than 30 days beyond the index procedure were deemed unrelated [4,13,15].Table 1 Harms categories.

Table 1Harm	Timing from index procedure	
Wound problems: intraoperative or post-procedural hemorrhage, hematoma, or seroma, post-operative infection, disruption of wound, incision and drainage, wound debridement, and treatment of dehiscence	Within 90 days	
Life threatening complications: acute myocardial infarction, pneumonia, respiratory problems, pulmonary embolism, and stroke	Within 30 days	
Neural trauma: lumbosacral spinal cord or nerve root injury, dural tear	Within 30 days	
Deep vein thrombosis (DVT)	Within 30 days	
Heterotopic ossification	Within 2 years	
Death	Within 30 days	

2.7 Statistical analysis

Descriptive statistics were used for demographic and baseline comorbidity data. Comparison of demographic and baseline comorbidity information was performed using a chi-square test of independence for categorical variables and an independent-samples t-test for continuous variables. Propensity scoring was utilized for age at index procedure, gender, race, year of index procedure, and all baseline comorbidities since subjects were not randomized to the treatment groups. Subsequent surgical procedures and harms were analyzed using Cox proportional hazards regression adjusted for propensity score.

Significance was set at 0.05 with no adjustments for multiple testing. Subjects were censored during two-year follow-up due to death unrelated to index procedure or loss of Medicare eligibility. In compliance with regulations, all outcome counts with less than 11 patients were censored to reduce potential for subject identification. All analyses utilized SAS Enterprise Guide 7.1 (Cary, NC).

3 Results

3.1 Study population

Following application of clinical inclusion and exclusion criteria, cohorts consisted of 2197 mild and 7416 outpatient laminectomy patients. mild patients were significantly older than laminectomy (76.7 years versus 73.4 years, respectively; p < 0.0001). A significant difference was seen between groups in gender, where 57.4 % of mild was female, compared to 43.3 % of laminectomy (p < 0.0001). Race was also significantly different between groups (p < 0.0001). (See Table 2.).Table 2 Patient demographics and baseline characteristics.

Table 2	mild N = 2197	Outpatient Laminectomy N = 7416	p-value	
Age, yearsa	
 Mean ± SD (N)	76.7 ± 7.7	73.4 ± 7.5	<0.0001	
 Median (Min, Max)	76.0 (47, 102)	73.0 (26, 96)		
Gender	
 Female	1262 (57.4 %)	3211 (43.3 %)	<0.0001	
 Male	935 (42.6 %)	4205 (56.7 %)		
Race	
 White	1962 (89.3 %)	6843 (92.3 %)	<0.0001	
 Black	137 (6.2 %)	242 (3.3 %)		
 Asian	20 (0.9 %)	56 (0.8 %)		
 Hispanic	22 (1.0 %)	30 (0.4 %)		
 Other	30 (1.4 %)	135 (1.8 %)		
 Unknown	26 (1.2 %)	110 (1.5 %)		
a Age as of index procedure date.

mild patients presented with a mean of 5.7 baseline comorbidities compared to 4.8 for outpatient laminectomy (p < 0.0001). Significant differences in incidence rates were found in 27 of 41 individual comorbidities, with higher rates in the mild group for all comorbidities with significant differences. The comprehensive list of baseline comorbidities is presented in Table 3.Table 3 Baseline comorbidities.

Table 3	mild N = 2197	Outpatient Laminectomy N = 7416	p-value	
Comorbidity Count	
Mean ± SD	5.7 ± 3.5	4.8 ± 3.1	<0.0001b	
Comorbidities	
Acquired immune deficiency syndrome	a	11 (0.1 %)	a	
Alcohol abuse	41 (1.9 %)	121 (1.6 %)	0.4531	
Deficiency anemias	603 (27.4 %)	1487 (20.1 %)	<0.0001b	
Autoimmune conditions	230 (10.5 %)	651 (8.8 %)	0.0159b	
Chronic blood loss anemia	57 (2.6 %)	133 (1.8 %)	0.0178b	
Leukemia	23 (1.0 %)	55 (0.7 %)	0.1613	
Lymphoma	33 (1.5 %)	95 (1.3 %)	0.4273	
Metastatic cancer	25 (1.1 %)	90 (1.2 %)	0.7744	
Solid tumor without metastasis, in situ	112 (5.1 %)	265 (3.6 %)	0.0012b	
Solid tumor without metastasis, malignant	358 (16.3 %)	1051 (14.2 %)	0.0135b	
Cerebrovascular disease	385 (17.5 %)	1026 (13.8 %)	<0.0001b	
Coagulopathy	131 (6.0 %)	428 (5.8 %)	0.7364	
Dementia	129 (5.9 %)	247 (3.3 %)	<0.0001b	
Depression	528 (24.0 %)	1443 (19.5 %)	<0.0001b	
Diabetes with chronic complications	560 (25.5 %)	1641 (22.1 %)	0.0010b	
Diabetes without chronic complications	766 (34.9 %)	2323 (31.3 %)	0.0018b	
Drug abuse	152 (6.9 %)	240 (3.2 %)	<0.0001b	
Heart failure	297 (13.5 %)	692 (9.3 %)	<0.0001b	
Hypertension, complicated	549 (25.0 %)	1322 (17.8 %)	<0.0001b	
Hypertension, uncomplicated	1895 (86.3 %)	5995 (80.8 %)	<0.0001b	
Liver disease, mild	178 (8.1 %)	571 (7.7 %)	0.5365	
Liver disease, moderate to severe	a	39 (0.5 %)	a	
Chronic pulmonary disease	622 (28.3 %)	1728 (23.3 %)	<0.0001b	
Neurological disorders affecting movement	186 (8.5 %)	499 (6.7 %)	0.0054b	
Other neurological disorders	88 (4.0 %)	240 (3.2 %)	0.0811	
Seizures and epilepsy	58 (2.6 %)	153 (2.1 %)	0.1050	
Obesity	689 (31.4 %)	2170 (29.3 %)	0.0586	
Paralysis	40 (1.8 %)	150 (2.0 %)	0.5502	
Peripheral vascular disease	667 (30.4 %)	1914 (25.8 %)	<0.0001b	
Psychoses	85 (3.9 %)	327 (4.4 %)	0.2719	
Pulmonary circulation disease	86 (3.9 %)	198 (2.7 %)	0.0025b	
Renal failure, moderate	440 (20.0 %)	1070 (14.4 %)	<0.0001b	
Renal failure, severe	82 (3.7 %)	173 (2.3 %)	0.0003b	
Hypothyroidism	658 (29.9 %)	1830 (24.7 %)	<0.0001b	
Other thyroid disorders	158 (7.2 %)	427 (5.8 %)	0.0135b	
Peptic ulcer with bleeding	48 (2.2 %)	157 (2.1 %)	0.8469	
Valvular disease	431 (19.6 %)	1236 (16.7 %)	0.0013b	
Weight loss	111 (5.1 %)	265 (3.6 %)	0.0017b	
Acute myocardial infarction	57 (2.6 %)	137 (1.8 %)	0.0287b	
Cardiac dysrhythmias	544 (24.8 %)	1646 (22.2 %)	0.0118b	
Fluid and electrolyte disorders	392 (17.8 %)	1004 (13.5 %)	<0.0001b	
a Amount censored due to count <11.

b Incidence was statistically significantly higher for mild patients.

3.2 Subsequent surgical procedure rate

Patients receiving mild experienced a 9.0 % subsequent surgical procedure rate compared to 5.5 % for outpatient laminectomy patients (p < 0.0001). The rate of disc procedures was not statistically significantly different between groups, and the count of endoscopic decompressions was less than 11 in each group so therefore the number was censored. The frequency of fusion, laminectomy/laminotomy and interspinous spacer with open decompression was significantly higher for mild patients (See Table 4.).Table 4 Rate of subsequent surgical procedures during two-year follow-up.

Table 4First Subsequent Surgical Procedure	mild N = 2197	Outpatient Laminectomy N = 7416	p-valueb	
Subsequent surgical procedure rate	198	9.0 %	410	5.5 %	<0.0001c	
 Disc procedure	24	1.1 %	76	1.0 %	0.1838	
 Endoscopic decompression	a	a	a	a	n/a	
 Fusion	79	3.6 %	190	2.6 %	<0.0001c	
 Laminectomy/laminotomy	134	6.1 %	283	3.8 %	<0.0001c	
 Spacer (with open decompression)	31	1.4 %	23	0.3 %	<0.0001c	
Note: Line item procedure values do not sum to total due to certain patients undergoing more than one subsequent surgical procedure on the same day.

a Amount censored due to count <11.

b All p-values have been adjusted by propensity score for age at index, gender, race, year of index, and all baseline comorbidities.

c Incidence of this subsequent intervention was statistically significantly lower for laminectomy patients.

3.3 Incidence of harms

mild patients experienced harms at a rate of 1.9 % compared to 5.8 % for outpatient laminectomy (p < 0.0001). Laminectomy patients experienced wound problems at a rate of 3.1 % versus 1.0 % for mild (p < 0.0001), and life-threatening complications at a rate of 2.1 % versus 1.0 % for mild (p < 0.0001). Injuries to the spinal cord, nerve roots or dura were reported at a rate of 1.4 % for laminectomy compared to no reported injuries for mild patients. Deep vein thrombosis was experienced by less than 11 laminectomy patients (exact number censored) and by none of the mild patients. All-cause mortality within 30 days of index occurred in 0.2 % of laminectomy (14 patients) and in less than 11 mild (exact number censored). (See Table 5.).Table 5 Incidence of harms during two-year follow-up.

Table 5Harms	mild N = 2197	Outpatient Laminectomy N = 7416	p-valuea	
Incidence of any harm	41	1.9 %	433	5.8 %	<0.0001b	
 Wound complications	22	1.0 %	231	3.1 %	<0.0001b	
 Life-threatening complicationsc	22	1.0 %	155	2.1 %	<0.0001b	
 Acute MI	11	0.5 %	79	1.1 %	0.0004b	
 Pneumonia	d	d	51	0.7 %	n/a	
 Respiratory problems	d	d	49	0.7 %	n/a	
 Stroke	d	d	20	0.3 %	n/a	
 Pulmonary embolism	d	d	17	0.2 %	n/a	
 Spinal cord or nerve root injury, and dural tear	0	0 %	107	1.4 %	n/a	
 DVT	0	0 %	d	d	n/a	
 Heterotopic ossification	0	0 %	d	d	n/a	
 Death	d	d	14	0.2 %	n/a	
a All p-values have been adjusted by propensity score for age at index, gender, race, year of index, and all baseline comorbidities.

b Incidence of this harm was statistically significantly lower for mild patients.

c Includes acute myocardial infarction, pneumonia, respiratory problems, stroke and pulmonary embolism.

d Amount censored due to count <11.

3.4 Overall composite rate of subsequent surgical procedures and harms

Combined rate of overall subsequent surgical procedures and harms was similar between groups at 10.8 % for mild and 11.0 % for outpatient laminectomy (p = 0.3845). (See Table 6.).Table 6 Overall rate of subsequent surgical procedures and harms during two-year follow-up.

Table 6	mild N = 2197	Outpatient Laminectomy N = 7416	p-valuea	
Subsequent surgical procedure rate	198	9.0 %	410	5.5 %	<0.0001b	
Incidence of any harm	41	1.9 %	433	5.8 %	<0.0001c	
Composite rate of harms and subsequent surgical procedures	237	10.8 %	818	11.0 %	0.3845	
a All p-values have been adjusted by propensity score for age at index, gender, race, year of index, and all baseline comorbidities.

b Rate was statistically significantly lower for laminectomy patients.

c Incidence was statistically significantly lower for mild patients.

4 Discussion

mild patients in this study were older and presented with more comorbidities than outpatient laminectomy patients. This may reflect a preference by providers to utilize mild for patients with more comorbidities or advanced age, and for whom open procedures are either not indicated or not desired [[3], [4], [5], [6]].

Subsequent surgical procedures were confirmed to involve the lumbar region, but it was not possible to determine if subsequent surgical procedures were performed at the same spinal level as the index procedure. This method for identifying subsequent surgical procedures has been documented in numerous previous reports analyzing surgical spine procedures using administrative claims [4,[10], [11], [12], [13], [14], [15]]. A review of these publications indicates a range of two-year subsequent surgical procedure rates for open decompression patients ranging from 7.2 % to just over 10 %. The subsequent surgical procedure rate for outpatient laminectomy patients in this report was 5.5 %, which is somewhat lower than these rates. This may reflect the requirement in this study for subsequent surgical procedures to include an LSS with NC diagnosis code in the claim's primary position. mild patients reported a 9.0 % rate of subsequent surgical procedures. While subsequent surgical procedure rates have not been previously reported for mild using administrative claims data, there have been two Level 1 RCTs with two-year follow-up that can be used as benchmarks. The ENCORE study investigators reported a two-year 5.6 % subsequent surgical procedure rate at the index level for mild patients [7]. In the MOTION RCT, 3.1 % of mild patients received a subsequent surgical procedure at the index level through two years [17]. These mild subsequent surgical procedure rates of 3.1 % and 5.6 % at two years are lower than the 9.0 % reported in this study, which likely reflects overcounting in Medicare claims data since repeat surgery cannot be confirmed to occur at the index level, but only in the overall lumbar region. Given this, the outpatient laminectomy subsequent surgical procedure rate may be overstated as well. In any event, the comparison of these two cohorts uses consistent coding rules and therefore provides valid relative subsequent surgical procedure outcomes.

At 1.9 %, the incidence of harms experienced by mild patients was statistically significantly lower than the 5.8 % reported by laminectomy patients. Specifically, outpatient laminectomy patients experienced wound problems at a rate three times higher, and life-threatening complications at a rate two times higher than mild patients, with both differences reaching statistical significance. Life threatening complications included acute myocardial infarction, pneumonia, respiratory problems, pulmonary embolism, and stroke. The only sub-category of life-threatening complications that included 11 or more patients in both cohorts and therefore was not censored, was acute myocardial infarction which occurred at a 0.5 % rate in the mild group and a rate over two times higher (1.1 %) for laminectomy patients (p = 0.0004). Reports of the ENCORE RCT at two-year follow-up indicated a 1.3 % rate of device- or procedure-related adverse events for mild patients with no serious device- or procedure-related adverse events occurring in the study [7]. In the MOTION RCT, through two years there were no reports of device- or procedure-related adverse events for mild patients [17]. These adverse event rates for mild in two Level 1 RCTs are in line with the 1.9 % reported in this analysis of Medicare claims. As a benchmark for open decompression at two years, the SPORT study reported an intraoperative complication rate of 10 %, and an overall postoperative complication rate of 12 % [18]. These SPORT complication rates are higher than the 5.8 % reported here for outpatient laminectomy and may reflect improvements in surgical techniques or the push toward outpatient surgery that has occurred since publication of the SPORT study.

This analysis compared outcomes of patients treated with mild to those who underwent outpatient laminectomy. Claims data showed that 20 % of ALL laminectomy patients were treated in the inpatient setting, and because of that sizeable percentage, a supplementary comparison of mild versus ALL laminectomy patients was conducted. The rate of subsequent surgical procedures for ALL laminectomy patients was 5.4 % which was statistically significantly lower than 9.0 % for mild. The incidence of any harm for ALL laminectomy patients was 8.4 % which was statistically significantly higher than 1.9 % for mild. It is interesting to note the differences in laminectomy patient two-year outcomes when comparing ALL laminectomy patients to the outpatient laminectomy cohort used in this study. The subsequent surgical procedure rate was similar between ALL laminectomy patients and the subgroup containing only outpatient laminectomy patients (5.4 % and 5.5 %, respectively). The incidence of harms was higher for ALL laminectomy patients at 8.4 % versus 5.8 % for outpatient laminectomy only, reflecting an incidence of harms for inpatient laminectomy patients of 18.8 %. The higher rate of harms for inpatient laminectomy may be attributable to inpatient laminectomy patients being older than outpatient laminectomy patients (74.5 years vs. 73.4 years, respectively; p < 0.0001) and having more baseline comorbidities (mean of 5.6 vs. 4.8, respectively; p < 0.0001).

In a meta-analysis of published studies of surgical treatment for LSS, Bays and colleagues reported that higher levels of presenting comorbidities were associated with an increased risk for complications related to the index surgical procedure [19]. In this study, despite the mild cohort having a significantly higher level of baseline comorbidities, incidence of harms for mild was significantly less, suggesting lower procedural risk for the minimally invasive mild procedure in higher risk patients.

This study used real-world Medicare claims data to compare outcomes for two treatments that occur at distinctly different timepoints on the LSS treatment algorithm. mild has been recommended by multiple published studies and reviews for use either as soon as LSS is diagnosed or after failure of the first ESI [3,[6], [7], [8], [9]]. Conversely, laminectomy, which involves longer recovery times and higher complication rates, appears later in the treatment continuum. Consistent with the marked separation in treatment algorithm positioning, these procedures are under the purview of different physician specialties with mild most often performed by interventional pain management, anesthesiology, physical medicine and rehabilitation, and interventional radiology physicians, while laminectomy is performed by spine surgeons. With different treating specialties and patients at divergent positions in their personal treatment journeys, use of Medicare claims data offers a valuable insight into real-world, unbiased comparison of patient outcomes. Availability of large numbers of patients combined with use of propensity scoring allowed for a balanced and valid method of comparing two procedures that otherwise would be impossible to reasonably study in a traditional controlled clinical trial setting.

Population-based studies generally include a large number of patients and therefore have strong statistical power. Specifically, this study used CMS RIF files which include all medical claims for 100 % of Medicare beneficiaries and are the most complete data source for Medicare claims analyses. There are some important limitations to this study. Using Medicare claims, it is unknown if subsequent surgical procedures involve the same spinal level as index, likely resulting in overcounting. Degree and anatomical cause of stenosis and number of spinal levels are not defined using claims data, and common patient reported outcome measures are not available. The observational nature of population-based studies can limit selection criteria precision potentially resulting in some residual confounding, although propensity scoring was used to reduce this possibility. Analysis of outcomes with patient counts less than 11 could not be performed due to required censoring [10,13,20].

5 Conclusion

mild can be considered a viable option for treatment of LSS with NC as evidenced by real-world data in this study. At two-years, mild patients experienced fewer harms and underwent more subsequent surgical procedures than outpatient laminectomy patients. The higher rate of subsequent surgical procedures for mild may be attributable to its position earlier in the LSS treatment algorithm. The overall rate of harms and subsequent surgical procedures was similar between groups, suggesting that mild should be considered as a treatment option, particularly for older patients with multiple comorbidities.

Declaration of competing interest

PS reports consulting or research grants from Medtronic, Saluda Medical, Biotronik, AIS Healthcare, Nalu, SPR Therapeutics and funded research from Vertos Medical. MD is a consultant for Abbott, Biotronik, Camber Spine, Globus, Nevro and LifeSpine. DR and NS report no conflicts. LP is a consultant for Medtronic and Saluda Medical, and holds stock options for Nalu and Saluda. JH reports no conflicts.

Acknowledgements

The authors thank Avania for all statistical analysis of Medicare claims data, and Medavise LLC for manuscript preparation assistance. Vertos Medical provided financial support for this research.
==== Refs
References

1 Katz J.N. Harris M.B. Clinical practice. Lumbar spinal stenosis N Engl J Med 358 8 2008 818 825 10.1056/NEJMcp0708097 18287604
2 Deyo R.A. Mirza S.K. Martin B.I. Kreuter W. Goodman D.C. Jarvik J.G. Trends, major medical complications, and charges associated with surgery for lumbar spinal stenosis in older adults JAMA 303 13 2010 1259 1265 10.1001/jama.2010.338 20371784
3 Deer T.R. Grider J.S. Pope J.E. Best practices for minimally invasive lumbar spinal stenosis treatment 2.0 (MIST): consensus guidance from the American society of pain and neuroscience (ASPN) J Pain Res 15 2022 1325 1354 10.2147/JPR.S355285 Published 2022 May 5 35546905
4 Tapp S.J. Martin B.I. Tosteson T.D. Understanding the value of minimally invasive procedures for the treatment of lumbar spinal stenosis: the case of interspinous spacer devices Spine J 18 4 2018 584 592 10.1016/j.spinee.2017.08.246 28847740
5 Mekhail N. Costandi S. Nageeb G. Ekladios C. Saied O. The durability of minimally invasive lumbar decompression procedure in patients with symptomatic lumbar spinal stenosis: long-term follow-up Pain Pract 21 8 2021 826 835 10.1111/papr.13020 33942964
6 Jain S. Deer T. Sayed D. Minimally invasive lumbar decompression: a review of indications, techniques, efficacy and safety Pain Manag 10 5 2020 Sep 331 348 32609052
7 Staats P.S. Chafin T.B. Golovac S. Long-Term safety and efficacy of minimally invasive lumbar decompression procedure for the treatment of lumbar spinal stenosis with neurogenic claudication: 2-year results of MiDAS ENCORE Reg Anesth Pain Med 43 7 2018 Oct 789 794 30199512
8 Deer T.R. Costandi S.J. Washabaugh E. The MOTION study: a randomized controlled trial with objective real-world outcomes for lumbar spinal stenosis patients treated with the mild® procedure: one-year results Pain Med 23 4 2022 Apr 8 625 634 35167700
9 Pryzbylkowski P. Bux A. Chandwani K. Minimally invasive direct decompression for lumbar spinal stenosis: impact of multiple prior epidural steroid injections Pain Manag 12 2 2022 149 158 10.2217/pmt-2021-0056 34344197
10 Martin B.I. Mirza S.K. Comstock B.A. Gray D.T. Kreuter W. Deyo R.A. Reoperation rates following lumbar spine surgery and the influence of spinal fusion procedures Spine 32 3 2007 382 387 10.1097/01.brs.0000254104.55716.46 17268274
11 Deyo R.A. Martin B.I. Kreuter W. Jarvik J.G. Angier H. Mirza S.K. Revision surgery following operations for lumbar stenosis J Bone Joint Surg Am 93 21 2011 Nov 2 1979 1986 22048092
12 Martin B.I. Mirza S.K. Flum D.R. Repeat surgery after lumbar decompression for herniated disc: the quality implications of hospital and surgeon variation Spine J 12 2 2012 89 97 10.1016/j.spinee.2011.11.010 22193055
13 Deyo R.A. Martin B.I. Ching A. Interspinous spacers compared with decompression or fusion for lumbar stenosis: complications and repeat operations in the Medicare population Spine 38 10 2013 865 872 10.1097/BRS.0b013e31828631b8 23324936
14 Kim C.H. Chung C.K. Park C.S. Choi B. Hahn S. Kim M.J. Lee K.S. Park B.J. Reoperation rate after surgery for lumbar spinal stenosis without spondylolisthesis: a nationwide cohort study Spine J 13 10 2013 Oct 1230 1237 24017959
15 Lad S.P. Babu R. Ugiliweneza B. Patil C.G. Boakye M. Surgery for spinal stenosis: long-term reoperation rates, health care cost, and impact of instrumentation Spine 39 12 2014 978 987 10.1097/BRS.0000000000000314 24718058
16 Elixhauser A. Steiner C. Harris D.R. Coffey R.M. Comorbidity measures for use with administrative data Med Care 36 1 1998 8 27 9431328
17 Deer T.R. Chafin T.B. Costandi S.J. The MOTION study: two-year results of a real-world randomized controlled trial of the mild® procedure for treatment of lumbar spinal stenosis [published online ahead of print, 2023 Sep 3] Pain Pract 2023 10.1111/papr.13293 10.1111/papr.13293
18 Weinstein J.N. Tosteson T.D. Lurie J.D. Surgical versus nonsurgical therapy for lumbar spinal stenosis N Engl J Med 358 8 2008 794 810 10.1056/NEJMoa0707136 18287602
19 Bays A. Stieger A. Held U. Hofer L.J. Rasmussen-Barr E. Brunner F. Steurer J. Wertli M.M. The influence of comorbidities on the treatment outcome in symptomatic lumbar spinal stenosis: a systematic review and meta-analysis N Am Spine Soc J 6 2021 Jun 2 100072
20 Meier S.K. Pollock B.D. Kurtz S.M. Lau E. State and government administrative databases: Medicare, national inpatient sample (NIS), and state inpatient databases (SID) programs J Bone Joint Surg Am 104 Suppl 3 2022 4 8 10.2106/JBJS.22.00620
