Comparative Effectiveness Assessment of Two Powered Surgical Stapling Platforms in Laparoscopic Sleeve Gastrectomy: A Retrospective Matched Study

Figures & data

Table 1 Patient Demographic Characteristics After Matching

	GST		SIG		SMD*
	N	%	N	%
	491	100.00%	491	100.00%
Age category, N/%
18–34	123	25.05%	122	24.85%	0.00
35–44	152	30.96%	163	33.20%	0.05
45–54	120	24.44%	119	24.24%	0.00
55–64	74	15.07%	67	13.65%	0.04
65–74	22	4.48%	19	3.87%	0.03
75 Plus	0	0.00%	1	0.20%	0.05
Female, N/%	407	82.89%	416	84.73%	0.05
Married, N/%	280	57.03%	272	55.40%	0.03
Race, N/%
Black	79	16.09%	87	17.72%	0.05
White	376	76.58%	371	75.56%	0.02
Other/unknown	36	7.33%	22	6.72%	0.05
Payer category, N/%
Commercial	281	57.23%	281	57.23%	0.00
Medicaid	121	24.64%	121	24.64%	0.00
Medicare	55	11.20%	61	12.42%	0.04
Other	34	6.92%	28	5.70%	0.05
Year of surgical admission, N/%
2017 (March 1 onwards)	125	25.46%	114	23.22%	0.05
2018	366	74.54%	377	76.78%	0.05

Note: *A standardized mean difference <0.10 is considered indicative of good covariate balance.

Abbreviations: BMI, body mass index, kg/m²; GST, ECHELON FLEX™ GST system; SMD, absolute standardized mean difference; SIG, Signia^TM Stapling System.

Table 2 Patient Clinical Characteristics After Matching

	GST		SIG		SMD*
	N	%	N	%
	491	100.00%	491	100.00%
CCI score, N/%
0	281	57.23%	278	56.62%	0.01
1–2	182	37.07%	187	38.09%	0.02
3–4	22	4.48%	22	4.48%	0.00
5 +	6	1.22%	4	0.81%	0.04
Elixhauser comorbidities**, N/%
Congestive heart failure	8	1.63%	10	2.04%	0.03
Cardiac arrhythmias	16	3.26%	12	2.44%	0.05
Hypertension, uncomplicated	233	47.45%	245	49.90%	0.05
Hypertension, complicated	23	4.68%	23	4.68%	0.00
Other neurological disorders	6	1.22%	8	1.63%	0.04
Chronic pulmonary disease	91	18.53%	100	20.37%	0.05
Diabetes, uncomplicated	75	15.27%	77	15.68%	0.01
Diabetes, complicated	29	5.91%	27	5.50%	0.02
Hypothyroidism	65	13.24%	73	14.87%	0.04
Renal failure	16	3.26%	20	4.07%	0.05
Liver disease	43	8.76%	37	7.54%	0.04
Rheumatoid arthritis/collagen vascular diseases	14	2.85%	11	2.24%	0.04
Deficiency anemia	17	3.46%	21	4.28%	0.04
Depression	119	24.24%	117	23.83%	0.01
BMI category, N/%
30 to 34.9	5	1.02%	4	0.81%	0.02
35 to 39.9	104	21.18%	98	19.96%	0.03
40 to 44.9	156	31.77%	147	29.94%	0.04
45 to 49.9	104	21.18%	110	22.40%	0.03
50 to 59.9	93	18.94%	102	20.77%	0.04
60 to 69.9	22	4.48%	22	4.48%	0.00
≥70	2	0.41%	3	0.61%	0.02
Unknown	5	1.02%	5	1.02%	0.00

Notes: *A standardized mean difference <0.10 is considered indicative of good covariate balance. **Patients were matched on Elixhauser comorbidities with prevalence ≥ 1.0% in the pooled sample.

Abbreviations: CCI, Charlson Comorbidity Index; GST, ECHELON FLEX™ GST system; SMD, absolute standardized mean difference; SIG, Signia^TM Stapling System.

Table 3 Hospital/Provider Characteristics After Matching

	GST		SIG		SMD*
	N	%	N	%
	491	100.00%	491	100.00%
Urban hospital, N/%	485	98.78%	490	99.80%	0.05
Teaching hospital, N/%	170	34.62%	181	36.86%	0.05
Hospital region, N/%
Midwest	90	18.33%	99	20.16%	0.05
Northeast	117	23.83%	110	22.40%	0.03
South	282	57.43%	282	57.43%	0.00
West	2	0.41%		0.00%	0.04
Hospital bed size, N/%
000–099	3	0.61%	0	0.00%	0.04
100–199	39	7.94%	33	6.72%	0.04
200–299	55	11.20%	63	12.83%	0.04
300–399	273	55.60%	284	57.84%	0.05
400–499	58	11.81%	51	10.39%	0.05
500+	63	12.83%	60	12.22%	0.02
Annual LSG volume, N/%
0–150	47	9.57%	41	8.35%	0.04
151–300	209	42.57%	199	40.53%	0.04
301–450	152	30.96%	159	32.38%	0.03
450+	83	16.90%	92	18.74%	0.05
Procedural physician specialty, N/%
Abdominal surgery or gastroenterology	12	2.44%	15	3.05%	0.04
General surgery	458	93.28%	461	93.89%	0.03
Other/unknown	21	4.28%	15	3.06%	0.04

Note: *A standardized mean difference <0.10 is considered indicative of good covariate balance.

Abbreviations: GST, ECHELON FLEX™ GST system; SMD, absolute standardized mean difference; SIG, Signia^TM Stapling System.

Figure 1 Standardized mean differences before and after matching*.

Note: *A standardized mean difference <0.10 is considered indicative of good covariate balance.

Table 4 Distribution of Observed Diagnoses and Procedures for Hemostasis-Related Complications During the Surgical Admission

	GST		SIG
	N	%	N	%
	491	100.00%	491	100.00%
Observed diagnoses
Acute posthemorrhagic anemia	2	0.41%	8	1.63%
Postprocedural hemorrhage following digestive system procedure	0	0.00%	2	0.41%
Observed procedures
Transfusion of nonautologous red blood cells into peripheral vein, percutaneous approach	1	0.20%	2*	0.41%
Transfusion of nonautologous platelets into peripheral vein, percutaneous approach	0	0.00%	1	0.20%

Note: *Both patients also received a diagnosis of acute posthemorrhagic anemia.

Figure 2 Incidence proportion* of patients with hemostasis-related complications during the surgical admission after matching (primary outcome).

Notes: *There were 11 patients with hemostasis-related complications in the SIG group and 3 patients with hemostasis-related complications in the GST group (see Table 4 for component diagnoses); the risk difference between the SIG group and GST group was 1.63% (95% CI, 0.15–3.11%, P=0.031); the Generalized Estimating Equations-based odds ratio (SIG = reference) accounting for hospital-level clustering via an exchangeable correlation matrix and robust standard errors was 0.28 (95% CI, 0.13–0.60, P=0.0012).

Abbreviations: GST, ECHELON FLEX™ GST system; SIG, SigniaTM Stapling System.

Table 5 Distributions of Total Hospital Costs, Length of Stay, and Operating Room Time for the Surgical Admission After Matching (Secondary Outcomes)*

Leak, N (%)	GST	SIG	P-value**
	N=491	N=491
	0	0	n/a
Total hospital costs (2018 USD)
	N=491	N=491	0.184
Mean	$10,666	$11,562
SD	$4453	$4282
Minimum	$6005	$5759
25th pct.	$8521	$9348
Median	$9771	$10,487
75th pct.	$11,825	$12,516
Maximum	$87,765	$49,321
Length of stay
	N=491	N=491	0.362
Mean	1.64	1.65
SD	0.77	1.31
Minimum	1	1
25th pct.	1	1
Median	2	1
75th pct.	2	2
Maximum	7	22
Operating room time
	N=461***	N=491	0.122
Mean	116.5	116.7
SD	39.2	34.6
Minimum	60.0	58.8
25th pct.	90.0	90.0
Median	105.6	114.6
75th pct.	133.8	130.0
Maximum	314.0	407.4

Notes: *All outcomes were measured during the surgical admission. **P-value for difference in means based on Generalized Estimating Equation model accounting for hospital-level clustering via an exchangeable correlation matrix and robust standard errors. ***Analysis of operating room time were limited to patients with operating room times falling between 30 minutes and 24 hours; 30 patients from the GST group were omitted from the analysis: 29 patients had operating room times = 0 and 1 patient had operating room time >24 hours.

Abbreviations: GST, ECHELON FLEX™ GST system; pct, percentile; SD, standard deviation; SIG, Signia^TM Stapling System; USD, United States dollars.

Table 6 Incidence Proportions of All-Cause Inpatient Readmission After Matching (Secondary Outcome)

Patients in Hospitals with**	GST		SIG		P-value*
	N	%	N	%
≥1 month of data after surgical admission	464	100.00%	473	100.00%	0.976
Readmission within 1 month post-discharge	10	2.16%	10	2.11%
≥2 months of data after surgical admission	441	100.00%	454	100.00%	0.763
Readmission within 2 months post-discharge	14	3.17%	13	2.86%
≥3 months of data after surgical admission	420	100.00%	442	100.00%	0.797
Readmission within 3 months post-discharge	15	3.57%	14	3.17%

Notes: *P-value based on Generalized Estimating Equation model accounting for hospital-level clustering via an exchangeable correlation matrix and robust standard errors. **Analyses of all-cause inpatient readmissions to the hospital in which the laparoscopic sleeve gastrectomy was performed were limited to patients in hospitals that continued to contribute data to the Premier Healthcare Database through or beyond the readmission identification time period after the surgical admission.

Abbreviations: GST, ECHELON FLEX™ GST system; SIG, Signia^TM Stapling System.