In-Hospital Outcomes and Cost Assessment Between Bipolar Versus Monopolar Transurethral Resection of the Prostate

Abstract

Purpose:

We compared the in-hospital outcomes between bipolar and monopolar transurethral resection of the prostate (B-TURP and M-TURP, respectively) on a real-world practice using a large database.

Patients and Methods:

Patients who underwent TURP were extracted from the Diagnosis Procedure Combination database, which is a case-mix administrative claims database in Japan. TURP procedures were classified into M-TURP and B-TURP groups according to intraoperative use or nonuse of D-sorbitol solution, respectively, which is the only nonelectrolyte bladder irrigation fluid for M-TURP available in Japan. To exclude causality among autologous and homologous transfusion events, we confined eligible hospitals to those in which no autologous blood preparation was undertaken for TURP and whose annual surgical caseloads were 15 cases or more. Multivariate analyses were conducted for homologous transfusion, postoperative complications, operative time, postoperative length of stay, and total costs.

Results:

There were 5155 M-TURP and 1531 B-TURP patients identified. The results for M-TURP vs B-TURP (effect sizes were evaluated with reference to M-TURP) were 2.3% vs 1.3% for transfusion (odds ratio [OR]=0.54; P=0.013), 3.3% vs 1.7% for postoperative complications (OR=0.46; P<0.01), 98 vs 116 minutes for operative time (20.5% increase; P<0.001), 8.65 vs 8.45 days for postoperative stay (3.6% reduction; P=0.003), and $6103 vs $6062 for cost (1.7% reduction; P=0.018).

Conclusion:

B-TURP had significantly lower rates of transfusion and postoperative complications, but a longer operative time. The impacts of B-TURP on shortening the hospital stay and lowering the costs were of little clinical significance.

Introduction

B enign prostate hyperplasia is a prevalent condition associated with lower urinary tract symptoms, commonly typified by urinary frequency, urgency, nocturia, weakened and intermittent urinary stream, and sensation of incomplete bladder emptying. Its prevalence rate is reported to be >50% in 60-year-old men, and as high as 90% by 85 years of age.¹

About 20% of patients with mild or severe symptoms are treated using several types of surgical procedures. Among these, transurethral resection of the prostate (TURP) is considered to be the gold standard.^1
–3 Conventional TURP uses monopolar technology (M-TURP) and is associated with several adverse effects, including morbidity related to blood loss and disturbances of serum fluid and mineral balance. In seeking to improve these negative aspects, TURP using bipolar technology (B-TURP) has been developed.

To date, several randomized controlled trials (RCTs) have been performed and have indicated some superiority of B-TURP over M-TURP.^4
–6 On the other hand, these previous RCTs had several limitations,⁷ and the sample sizes were too small to detect low incidences of events. Furthermore, the clinical situations in RCTs, such as surgeons and facilities, do not necessarily reflect average clinical practices. Because of the low external validity of RCTs, measurement of the effectiveness derived from real-world clinical practice is important.

The present study evaluated the impacts of B-TURP on several clinical outcomes in comparison with M-TURP, with adjustment for patient background data, using a nationwide administrative database in Japan, known as the Diagnosis Procedure Combination (DPC) database.

Patients and Methods

The DPC database

The nature of the DPC database has been described.^8
–10 Briefly, the database is a case-mix inpatient administrative claims database in Japan that has been ongoing since 2002. The database contains: (1) The main diagnoses, comorbidities at admission, and complications after admission, coded according to the International Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) codes; (2) the surgical procedures accompanied by original Japanese K-codes; (3) the discharge status; and (4) the use of medical resources, such as drugs. The number of patients in the database was 2.86 and 2.57 million from 855 and 818 hospitals in 2008 and 2009, respectively, which represented approximately 40% of all acute care inpatient hospitalizations in Japan. Study approval was obtained from the Institutional Review Board of the University of Occupational and Environmental Health, Fukuoka, Japan.

Sampling strategy

Data were collected from July 1 to December 31 of 2008 and 2009 (6 months per year). The patients included in the present study were those who received a diagnosis of hyperplasia of the prostate (ICD-10 code N40), retention of urine (R33), or bladder-neck obstruction (N320), and underwent TURP (assigned K-code K841). Patients who underwent transurethral laser surgery, transurethral microwave thermotherapy, or high intensity focused ultrasound surgery were excluded. Given the anonymous nature of the data collection process, informed consent was not required.

We extracted the following information as study variables: Age and comorbidities at admission as patient characteristics; and teaching status (academic or community), bed volume, and hospital volume (HV; annual operative caseload of each hospital) as hospital characteristics. HV was divided into four categories with reference to a previous publication⁹: Low, ≤14 TURPs/y; medium, 15–29 TURPs/y; high, 30–49 TURPs/y; and very high, ≥50 TURPs/y. The Charlson comorbidity index (CCI) was calculated for preexisting risk adjustment.^11,12

The following outcome indicators were obtained: (1) Homologous blood transfusion; (2) postoperative complications; (3) mortality; (4) operative time (including time under epidural anesthesia, management of general anesthesia, and preparation for monitoring and position); (5) postoperative length of stay; and (6) total costs ($1=80 Japanese yen). Postoperative complications were defined as: Transurethral resection syndrome (identified by hyponatremia [E871], pulmonary edema [J81], or water intoxication [E877]); sepsis; acute urinary tract infection; injuries to the urethra, rectum or bladder; stroke; cardiac events; venous thromboembolism; and respiratory failure. Acute cystitis was excluded from our categorization of acute urinary tract infection because of its frequency under the catheterization condition.¹³ Total costs included doctor and administration fees, operation and anesthesia costs, medications, laboratory tests, and imaging tests.

Selection of hospitals to exclude autologous transfusion influence

We needed to regulate the cause-and-effect relationship between autologous and homologous blood transfusion. Autologous blood is more likely to be stored, if the physicians anticipate the surgery will be bloody because of, for example, a large prostate volume. In Japan, the cost of autologous blood storage is not reimbursed unless the blood is actually used, which may lead to autologous transfusion for trivial bleeding cases. Therefore, autologous blood storage affects both the outcome (homologous transfusion) and the cause (difficulty of surgery).

To regulate this causal relationship, we confined eligible hospitals to those in which all surgeries were undertaken without autologous blood preparation and whose HV was ≥15 (Fig. 1). We presumed that these hospitals had a policy that autologous blood preparation is not necessary for TURP.

FIG. 1.

The flowchart of enrollment approach. D-sorbitol solution is the only irrigation fluid for monopolar transurethral resection of the prostate (M-TURP) available in Japan. Eligible hospitals were confined to ones presumably with the policy that autologous blood preparation is not necessary for TURP. HV=hospital volume; B-TURP=bipolar transurethral resection of the prostate; ICD-10=International Classification of Diseases and Related Health Problems, Tenth Revision.

Discrimination between monopolar and bipolar TURPs

The patients were divided into M-TURP and B-TURP groups according to the use of D-sorbitol solution on the operation day. D-sorbitol solution is the only nonelectrolyte bladder irrigation fluid for M-TURP available in Japan. We categorized the patients undergoing TURP with and without D-sorbitol liquid into the M-TURP and B-TURP groups, respectively (Fig. 1).

Statistical analysis

In univariate comparisons, categorical data were compared by the chi-square test, and numerical data were compared by the Mann–Whitney U test. Multiple logistic regression analyses were performed to evaluate the effects of homologous transfusion and overall postoperative complications. Multiple linear regression analyses were performed to estimate the impacts of B-TURP compared with M-TURP on the operative time, postoperative length of stay, and total costs. These three dependent variables were transformed into logarithms (base 10) when the analyses were performed. Adjusted factors in the multivariate analyses were age, CCI, teaching status, HV, and bed volume. The threshold for significance was a value of P<0.05. All statistical analyses were conducted using SPSS version 19.0 (IBM, Chicago, IL).

Results

Among 5.43 million patients, 5155 M-TURP and 1531 B-TURP patients were identified in 222 hospitals (Fig. 1). The B-TURP group contained more comorbid cases, and its share was biased to academic and larger bed volume hospitals (Table 1). Regarding the univariate comparisons, homologous transfusion, overall postoperative complications, and postoperative length of stay favored the B-TURP group, although this group had a longer operative time.

Table 1.

Patient Characteristics and Outcomes

	TURP modality
	Monopolar	Bipolar	P value
Overall	5155	1531
Age (mean±SD)	72.7 ± 7.5	72.7 ± 7.5	0.760^a
Charlson comorbidity index (%)			<0.001
0	4246 (82.4)	1162 (75.9)
1	674 (13.1)	275 (18.0)
≥2	235 (4.6)	94 (6.1)
Academic hospital (%)	333 (6.5)	205 (13.4)	<0.001
Hospital volume (%)			0.072
15–29/y	1735 (33.7)	532 (34.7)
30–49/y	1950 (37.8)	608 (39.7)
≥50/y	1470 (28.5)	391 (25.5)
Bed volume ≥400 (%)	3170 (61.5)	1005 (65.6)	0.001
Outcomes
Homologous transfusion (%)	118 (2.3)	20 (1.3)	0.018
Postoperative complications (%)
Overall	172 (3.3)	26 (1.7)	0.001
Transurethral resection syndrome	16 (0.3)	0 (0.0)	0.029
Sepsis and acute UTI^b	104 (2.0)	14 (0.9)	0.004
Injury of urethra, rectum, bladder	3 (0.1)	1 (0.1)	0.920
Stroke	7 (0.1)	1 (0.1)	0.484
Cardiac event	24 (0.5)	8 (0.5)	0.777
Venous thromboembolism	0 (0.0)	0 (0.0)	–
Respiratory failure	22 (0.4)	3 (0.2)	0.194
Mortality (%)	3 (0.1)	1 (0.1)	0.920
Operative time (min, mean±SD)	98 ± 62	116 ± 74	<0.001^a
Postoperative length of stay (d, mean±SD)	8 ± 4.7	7 ± 5.0	0.003^a
Total charge ($, mean±SD)^c	6103 ± 2100	6062 ± 2 020	0.480^a

Compared using the Mann–Whitney U test. The other comparisons were made using the chi-square test.

Acute cystitis is excluded.

$1=80 Japanese yen.

TURP=transurethral resection of the prostate; SD=standard deviation; UTI=urinary tract infection.

Table 2 shows the multivariate logistic regression analyses for homologous transfusion and overall postoperative complications. Both outcomes were significantly affected by bipolar use and high CCI. High volume (≥50 TURPs/y) also appeared to be a risk reducer of both, but did not reach a significant level in terms of homologous transfusion.

Table 2.

Multivariate Logistic Regression Analyses for Homologous Transfusion and Overall Postoperative Complications

	Homologous transfusion			Overall complications
	OR	95% CI	P value	OR	95% CI	P value
Bipolar (reference, monopolar)	0.54	0.33–0.88	0.013	0.46	0.30–0.69	<0.001
Age (reference, ≤64)
65–74	1.16	0.78–3.34	0.200	0.82	0.54–1.22	0.331
≥75	4.26	2.13–8.51	< 0.001	1.00	0.66–1.49	0.998
Charlson comorbidity index (reference, 0)
1	1.10	0.67–1.79	0.710	1.87	1.30–2.66	0.001
≥2	2.81	1.69–4.69	< 0.001	2.60	1.59–4.23	<0.001
Academic hospital (reference, no)	0.94	0.48–1.84	0.857	1.19	0.71–1.96	0.500
Hospital volume (reference, 15–29/y)
30–49/y	1.04	0.71–1.55	0.828	0.78	0.55–1.08	0.135
≥50/y	0.65	0.40–1.05	0.080	0.66	0.45–0.97	0.035
Bed volume ≥400(reference, <400)	1.22	0.84–1.76	0.302	1.35	0.98–1.85	0.062

CI=confidence interval; OR=odds ratio.

Table 3 shows the multivariate linear regression analyses for operative time, postoperative length of stay, and total costs. All three dependent variables were converted to log-10 values for these regression analyses. For readers' convenience, the output data displayed in Table 3 were returned to the original (nonlogarithmic) numbers. B-TURP resulted in a significantly longer operative time (20.5% increase, P<0.001), shorter postoperative stay (3.6% reduction, P=0.003), and lower total costs (1.7% reduction, P=0.018).

Table 3.

Multivariate Linear Regression Analyses for Operative Time, Postoperative Length of Stay, and Total Costs (Under Log–10 Transformations)

	Operative time (min)^a			Postoperative length of stay (d)^a			Total costs ($)^{a b}
	Estimate	95% CI	P value	Estimate	95% CI	P value	Estimate	95% CI	P value
Intercept	109.3			8.546			6701
Bipolar (reference, monopolar)	×1.205	1.173–1.239	<0.001	×0.964	0.940–0.988	0.003	×0.983	0.969–0.997	0.018
Age (reference, ≤64)
65–74	×1.014	0.981–1.048	0.403	×0.907	0.881–0.935	<0.001	×0.932	0.916–0.948	<0.001
≥75	×1.011	0.986–1.036	0.407	×0.948	0.927–0.969	<0.001	×0.951	0.939–0.963	<0.001
Charlson comorbidity index (reference, 0)
1	×0.996	0.964–1.029	0.805	×1.075	1.043–1.107	<0.001	×1.055	1.037–1.073	<0.001
≥2	×0.964	0.914–1.016	0.168	×1.160	1.107–1.217	<0.001	×1.137	1.106–1.169	<0.001
Academic hospital (reference, no)	×1.172	1.122–1.224	<0.001	×0.908	0.873–0.945	<0.001	×1.039	1.015–1.062	0.001
Hospital volume (reference, 15–29/y)
30–49/y	×0.978	0.952–1.005	0.113	×0.987	0.963–1.011	0.283	×0.999	0.985–1.014	0.919
≥50/y	×0.885	0.859–0.912	<0.001	×0.993	0.967–1.020	0.624	×0.982	0.967–0.997	0.021
Bed volume ≥400 (reference, <400)	×0.867	0.846–0.889	<0.001	×0.927	0.907–0.948	<0.001	×0.954	0.942–0.966	<0.001

Transformed into log–10 values for the analysis. The data displayed in this table are the numbers in nonlogarithmic values.

$1=80 Japanese yen.

CI=confidence interval; OR=odds ratio.

Discussion

In the present study, we detected significantly favorable results for B-TURP regarding homologous transfusion, overall postoperative complications, postoperative length of stay, and total costs. The operative time, however, tended to elongate by about 20.5% for B-TURP.

As of 2009, two types of B-TURP devices have been approved by the Ministry of Health, Labour and Welfare, Japan: The TURis^® (transurethral resection in sasline) system (Olympus, Tokyo, Japan) and the AUTOCON^® II 400 (Storz, Tuttlingen, Germany). The distribution of use of these B-TURP devices in the present study was unclear. According to a nationwide questionnaire survey carried out by the Japanese Urological Association to reveal the trends of surgical modalities for benign prostate hyperplasia,¹⁴ all B-TURP surgeries (n=2494) used the TURis system. The response rate was 42.1%. This implies that the vast majority of B-TURP surgeries in Japan are undertaken using the TURis system.

Regarding comparisons of M-TURP and B-TURP to date, several RCTs and their meta-analyses have been published. The issue of whether B-TURP holds superiority with less bleeding remains controversial, however. Among three large systematic reviews,^4
–6 all three found no significant difference in homologous transfusion, while two of them reported significantly lower rates of clot retention incidence.^4,6 In addition, Mamoulakis and associates¹⁵ performed a subgroup analysis focused on a bipolar device, the PlasmaKinetic system, and detected an improved safety benefit regarding transfusion.

One¹⁶ of six RCTs regarding the TURis system^16

–21 and no trials regarding the Vista system²² or AUTOCON II 400 system²³ showed significant differences for transfusion.

As theoretical support, some ex vivo experiments have shown that a bipolar current has the nature of deep coagulation and a “cut-and-seal” property.^24
–26 The authors indicated that these characteristics may contribute to a good hemostasis capacity of B-TURP.

To detect a blood transfusion difference between 2.3% and 1.3% in an RCT, the required sample size is 2774 cases per group under the conditions of alpha error=0.05 and beta error=0.80, which is an unfeasible number. Therefore, we infer that many RCTs and meta-analyses have been underpowered to judge transfusion superiority.

In general, RCTs have several limitations, even though they are the most reliable methods for determining the effects of treatments. Such trials are performed under strictly controlled clinical settings, and the issue of whether their results are applicable to routine clinical practice (external validity) is often of concern.⁷ To overcome this low external validity, measurement of the effectiveness derived from real-world clinical practice is important.

Regarding postoperative complications, all three systematic reviews reported that B-TURP offered advantages for transurethral resection syndrome. This benefit is derived from the use of saline irrigation. Many RCTs have reported that the postoperative serum sodium changes were smaller in the B-TURP arm.^6,16,18 Theoretically, this B-TURP nature of less influence on the mineral balance can also provide benefit for the cardiopulmonary circulation, although there is no evidence to show that B-TURP reduces some rare but life-threatening adverse events, such as cardiac or pulmonary failure.

The operative time was increased by 20.5% in the B-TURP group. One possible reason is the small size of the loop in the TURis system. As mentioned, the TURis system appears to have the majority share in Japan. The available TURis loop has a caliber of 5.0 mm and a gauge of 0.25 mm, compared with the caliber of 6.2 mm and gauge of 0.35 mm for the M-TURP loop.^6,25 In addition, bipolar groups were biased to teaching hospitals and high-CCI cases in the present study. Therefore, the learning curve of trainee surgeons and careful watching for high-comorbidity patients during the operation might have influenced the longer operative time. One TURis RCT²⁰ reported a 25% longer operation time in the TURis arm, but this is not a common result in RCTs on the TURis system. One systematic review⁵ described no significant difference in the operative time, while another⁶ abandoned a meta-analysis because of the large heterogeneity attributed to several operator-dependent or technical characteristics.

In this study, B-TURP achieved reductions in the postoperative length of stay and total costs. Both reduction sizes, however, were very slight and were not sufficient to be appreciated as clinically meaningful differences. In fact, several RCTs have supported a shorter duration of postoperative catheterization and shorter length of stay.^6,22 Some caution is needed in the interpretation of our results because both the length of stay and total costs were largely dependent on the social background and healthcare support system, which produce difficulties for comparisons with data from other countries. For example, Japan is characterized by a longer length of stay for acute care patients compared with Western countries.^27,28 A survey on perioperative management of TURP around 2007 in Japan²⁹ reported that the postoperative length of stay for M-TURP and TURis was 8.3±7.8 and 7.1±3.6 days, respectively, and documented that most Japanese patients want to stay hospitalized until their urinary catheter is removed, because the national health insurance system covers these long postoperative stays.

The present study involved several limitations. First, the use of an administrative claims database could have led to an underestimation or overestimation of comorbidities or complications. In particular, some D-sorbitol solution used for M-TURPs could have been missed from registration in the database. These M-TURP cases would be misallocated to the B-TURP group. This contamination effect, however, would reduce the differences in the effect sizes and make the analyses underpowered. Therefore, the statistical analyses were shifted to be robust. In addition, because these mistakes would cause losses of reimbursement (revenue decrease) for each hospital, we think that the influence was definite. Second, smaller hospitals were less likely to participate in the DPC database.³⁰ Likewise, day-surgeries were not included in our analysis. Therefore, the possibility of sampling bias cannot be completely ruled out. Third, we could not obtain several clinical parameters, such as prostate size, resection volume, clot retention, serum sodium and hemoglobin changes, voiding function, or International Prostate Symptom Scores. Despite these limitations, our use of the nationwide database enabled us to reveal today's therapeutic outcomes for TURP procedures based on real-world data.

Conclusion

We found that patients who underwent B-TURP had significantly lower incidences of homologous transfusion and postoperative complications, shorter postoperative hospital stay, lower costs, and longer operative time than patients who underwent M-TURP, as evaluated by an analysis of a nationwide administrative database in Japan.

Footnotes

Acknowledgments

The present study was funded by a Grant-in-Aid for Research on Policy Planning and Evaluation from the Ministry of Health, Labour and Welfare, Japan (Grant number: H22-Policy-031) and by the Funding Program for World-Leading Innovative R&D on Science and Technology (FIRST program) from the Council for Science and Technology Policy, Japan (Grant number: 0301002001001).

Disclosure Statement

No competing financial interests exist.

Abbreviations Used

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