Retrosigmoid Versus Translabyrinthine Approach to Acoustic Neuroma Resection: A Comparative Cost-Effectiveness Analysis

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1 The Laryngoscope VC 2015 The American Laryngological, Rhinological and Otological Society, Inc. TRIOLOGICAL SOCIETY CANDIDATE THESIS Retrosigmoid Versus Translabyrinthine Approach to Acoustic Neuroma Resection: A Comparative Cost-Effectiveness Analysis Maroun T. Semaan, MD; Cameron C. Wick, MD; Kimberly J. Kinder, MD; John G. Stuyt, MD; Rebecca L. Chota, BS; Cliff A. Megerian, MD Objectives/Hypothesis: Approach-specific economic data of acoustic neuroma (AN) resection is lacking. The purpose of this study was to analyze and compare adjusted total hospital costs, hospital and intensive care unit (ICU) length of stay (LOS), and associated factors in AN patients undergoing resection by translabyrinthine (TL) approach versus retrosigmoid (RS) approach. Study Design: Retrospective chart review. Methods: A total of 113 patients with AN undergoing TL (N 5 43) or RS (N 5 70) surgical resection between 1999 and 2012 were analyzed. Data including age, health status, preoperative hearing, tumor size, postoperative complications, hospital, ICU LOS, and disposition after discharge were collected from medical records and compared between both groups. Cost data was obtained from the hospital finance department and adjusted based on the Consumer Price Index for Results: There were no significant differences in demographic data, preoperative hearing, preoperative health status, or postoperative complication rate. Total hospital LOS and ICU LOS were significantly longer in the RS compared to the TL group ( vs days; P < 0.001, and vs days; P , respectively). Tumors were larger in RS compared to the TL group ( cm vs cm, respectively; P ). When patients were stratified by tumor size < or 2 cm, the total hospital LOS remained greater in the RS group in both subgroups (< and 2 cm, P < 0.001, and P , respectively). However, there was no difference in the total ICU LOS between both subgroups. The adjusted mean total hospital cost was higher in the RS compared to the TL group ($25, ,968 vs. $16, ,724; P < 0.001). The adjusted mean total hospital cost was greater in the RS group with tumor < 2cm(P < 0.001) but not significantly different in patients with tumors 2 cm. Univariate analysis showed that greater tumor size, poorer preoperative health status, the presence of major postoperative complications, and the RS approach were independently significantly associated with higher total hospital LOS (P , P , P , and P < 0.001, respectively) and a higher adjusted total hospital cost (P < 0.001, P , P , and P < 0.001, respectively). Conclusion: Hospital LOS and total adjusted costs are significantly less for patients undergoing translabyrinthine acoustic neuroma resection compared to the retrosigmoid approach. Many factors appear to influence these differences. Economic considerations in addition to tumor characteristics and surgeon preference should be considered in future acoustic neuroma resections. Key Words: Acoustic neuroma, cost analysis, hospital length of stay, retrosigmoid, translabyrinthine. Level of Evidence: 2c. Laryngoscope, 126:S5 S12, 2016 INTRODUCTION Acoustic neuromas (AN) or vestibular schwannomas are benign tumors of the cochleovestibular nerve. They represent 8% to 10% of all intracranial tumors and 80% From the University Hospitals Ear, Nose, and Throat Institute, Department of Otolaryngology Head and Neck Surgery (M.T.S., C.C.W., K.J.K., J.G.S., C.A.M.), University Hospitals Case Medical Center; and the Case Western University School of Medicine (R.L.C.), Cleveland, Ohio, U.S.A. Editor s Note: This Manuscript was accepted for publication September 8, Send correspondence to Maroun T. Semaan, University Hospitals Ear, Nose and Throat Institute, LKS 5045, Euclid Ave, Cleveland, OH, maroun.semaan@uhhospitals.org Publication of this work as a supplement was supported in part by the Richard and Patricia Pogue Endowed Chair in Otologic Surgery and Hearing Sciences at University Hospitals Case Medical Center. The authors have no other funding, financial relationships, or conflicts of interest to disclose. DOI: /lary to 90% of all tumors at the cerebellopontine angle (CPA). The incidence of sporadic AN is estimated at 1.0 per 100,000 persons per year. 1 Symptomatic patients typically present with ipsilateral hearing loss, tinnitus, and/or vestibular dysfunction. In larger tumors, complaints attributable to facial nerve, trigeminal nerve, and/or brainstem compression might be present. 2 Diagnostic workup consists of history, physical exam, audiogram, and imaging. Gadolinium-enhanced magnetic resonance imaging (MRI) is the preferred imaging modality. Current treatment options include watchful waiting, microsurgical excision, and/or stereotactic radiation (i.e., Gamma Knife or cyberknife). Specific treatment methodology is chosen based on the hearing status, comorbidities, tumor size and location, and physician preference. 3 5 If surgical treatment is favored, a translabyrinthine (TL), retrosigmoid (RS), or middle cranial fossa approach can be used for tumor removal. In this study, we focus S5

2 on the TL and RS approaches. During the study period, the number of patients who underwent a middle cranial fossa approach was small, hence precluding meaningful analysis. In the TL approach, the surgeon performs a mastoidectomy and labyrinthectomy to expose the internal auditory canal (IAC) from the lateral aspect. The labyrinthectomy results in complete loss of hearing in the operated ear. However, the approach affords excellent exposure of the IAC and CPA, with minimal cerebellar retraction. The RS involves a suboccipital craniotomy to expose the cerebellopontine angle from the posterior aspect. The advantages of this approach are excellent CPA exposure and the possibility of hearing preservation in selected cases. However, it is challenging to access the lateral IAC or fundus, and the approach often requires cerebellar retraction to allow adequate exposure of the posterior fossa. Multiple studies have been published comparing facial nerve and hearing outcomes among the listed approaches. 6 8 In a large meta-analysis, 8 overall facial function preservation was 74% with the TL approach and 90% with the RS approach. The overall hearing preservation rate in the RS approach was 31%. Hospitals and surgeons with a higher surgical volume had a better outcome when compared to those with a lower surgical volume. Barker et al. 9 reported that 12.3% of patients who had surgery at a low-volume hospital were discharged to a short-term care unit or long-term rehabilitation facility compared to 4.1% in higher caseload hospitals. Their survey did not, however, compare differences between the types of surgical approaches. In addition to outcomes data, economic analyses have garnered increasing attention in our current health care environment. The cost of health care and annual budgetary debates have and will continue to force physicians in the United States to be conscious of the underlying expense associated with the care they provide. Socioeconomic analyses are inherently complex on account of the many patient and medical variability that accrue expenses. Furthermore, the wide spectrum of treatment modalities pertaining to acoustic neuroma management further complicates the picture. 5 Ahmed et al. 10 reviewed the California Hospital Inpatient Discharge Databases from 1996 until 2010 and noted that the overall volume of annual surgical cases of AN surgery decreased by 28.5%. Compared to the previous decade, the study showed a 2.5-fold increase in the median total hospital charges. Decreased hospital length of stay (LOS) and total hospital charges were more likely in high-volume centers. Patients with Medicaid (Medi-Cal), Medicare, older than 65 years or with medical comorbidities had higher total charges. These results were comparable to a nationwide hospital database analysis showing increased total charges over time and independently, higher total charges in patients with nonprivate insurance, higher comorbidities, and age older than 65 years. 11 Although previous studies have compared hospital LOS and total hospital costs, an approach-specific cost analysis is lacking in the literature. The purpose of this study is to compare adjusted total hospital costs, S6 hospital LOS, and intensive care unit (ICU) LOS in patients undergoing AN resection by a TL versus a RS approach, and analyze potential contributing factors. We hypothesize that there is no difference in adjusted total hospital cost, hospital LOS, and ICU LOS between both groups. We also explore the potential contribution of complications, tumor size, and/or comorbidities to the adjusted total cost and LOS. MATERIALS AND METHODS Patients Following departmental and institutional review board approval ( ), a retrospective chart review was conducted on 113 patients with AN from our tertiary neurotologic and skull base referral practice who underwent a TL or RS resection between 1999 and All patients had an International Classification of Diseases-9 code of and a Current Procedural Terminology code of associated with their hospital stay. Patients with prior surgical or radiation therapy were excluded. Patients were de-identified, and data was entered into a Microsoft Excel spreadsheet. Relevant data such as demographics; preoperative symptoms; tumor characteristics; surgical approach; and postoperative hospital course, including complications, length of stay, and discharge status, were collected from both paper and electronic medical records. Patients were divided into treatment groups of RS (70 patients) and TL (43 patients). Demographic and patient data is shown in Table I. The mean age was years in the TL group and years in the RS group. A total of 46.5 % of patients in the TL group and 44.3% in the RS group were males. The mean body mass index was and in the TL and RS, respectively. The mean American Society of Anesthesiologists (ASA) physical classification system was in the TL and in the RS group. There was no difference between both groups. Preoperative hearing was classified using the American Academy of Otolaryngology Head and Neck Surgery 1995 guidelines. Audiometric data was available preoperatively in 41 and 65 patients from the TL and RS groups (Table I), respectively. There was no difference in the preoperative hearing between both groups (P ). Tumor Size Gadolinium-enhanced MRI or fast imaging employing steady-state acquisition sequence images were used to determine tumor size. The tumor size was obtained by measuring the greatest diameter on a single image. In some instances, this included both the intracanalicular and extracanalicular dimensions. When actual films were not available for review, outside reports were used if they clearly provided the maximal tumor diameter. Because size is a known prognostic factor affecting neural outcome and complication rate, patients were stratified into two groups: tumor size < 2cmand 2 cm. This cutoff was chosen because tumors smaller than 2 cm tend to be intracanalicular, with a small CPA component without radiographic evidence of brainstem compression, whereas tumors larger than 2 cm often have a significant CPA component, with some degree of radiographic brainstem compression. Accurate size description was not available in one patient in the RS group. However, this patient was not excluded from the study due the fact that financial data relevant to the analysis was available. In the TL group, the mean tumor size was cm. In the RS group, the mean tumor size was cm (P ). In the TL group,

3 TABLE I. Demographics, Preoperative Hearing Status, and Tumor Size of Patients Who Underwent Translabyrinthine or Retrosigmoid Resection of Acoustic Neuroma. Demographics TL (n 5 43) RS (n 5 70) P Age (year)* Male 20 (46.5) 31 (44.3) 0.81 Female 23 (53.5) 39 (55.7) 0.81 BMI* ASA* Hearing Class (n 5 41) (n 5 65) p A 10 (24.4) 22 (33.8) B 12 (29.3) 16 (24.6) C 2 (4.9) 4 (6.2) D 17 (41.4) 23 (35.4) 0.74 Tumor Size p All tumors (n 5 43) (n 5 69) Size (cm)* Tumors < 2cm (n5 34) (n 5 33) Size (cm)* Tumors 2cm (n5 9) (n 5 36) Size (cm)* *Values are mean 6 standard deviation. Significant value (P 0.05) Mann-Whitney U test unless indicated otherwise. v 2 test or Fischer s exact test. ASA 5 American Society of Anesthesiologists; BMI 5 body mass index; PTA 5 pure-tone average; RS 5 retrosigmoid; SD 5 speech discrimination; Hearing Class ranked according to Committee on Hearing and Equilibrium s 1995 guideline. A: PTA 30 db and SD 70%; B: PTA db and SD 50%; C: > 50 db and SD 50%; and D: PTA at any level and SD < 50%. 79% of tumors were < 2 cm compared to 47.8% in the RS group. In tumors 2 cm, the mean size was cm and cm in the TL and RS groups, respectively (P ). Complications Postoperative complications were classified into medical and surgical, and minor versus major (Table II). Complications were considered major when they had a presumed impact on hospital stay. Although some of the listed minor surgical complications might be expected, such as tinnitus, imbalance, or headache, they were included in the analysis with regard to their potential implication on the postoperative hospital stay or rehabilitative process. Disposition The discharge disposition whether the patient had a routine discharge to home or residence, or a short- or long-term facility (skilled nursing facility [SNF]) were recorded in all 113 patients. The 30-day readmission rate and the need for subsequent adjuvant radiotherapy were also analyzed between both groups. These variables were analyzed because of their impact on the total cost, unaccounted in the total hospital charges. Financial Data Financial information pertaining to the total hospital charges (US dollars) was obtained from our hospital s finance department. Due to overhauls in the billing process and data collection at our institution between 1999 and 2011, complete financial information for all patients was not available. The primary outcome measure was total cost associated with the hospital admission, which included but was not limited to operative costs, bed charges, medications, nursing, secondary procedures, and inpatient rehabilitation therapy. When data was available, further analysis on total operating room charges was extracted and analyzed. Disposition to home, skilled nursing, or long-term acute care facilities was documented but not accounted for in the total cost. No postdischarge care, follow-up, or home nursing care was included in this analysis. All dollar figures were adjusted to 2013 inflation rates based on the Consumer Price Index for 2013 and using the adjustment coefficient generated by the inflation calculation formula ( Medicare payments under the acute inpatient prospective payment system (IPPS) are based on per-discharge rates. To gauge the patient s need, Medicare assigns discharges to Medicare severity diagnosis related groups (MS-DRG). 12,13 Each MS-DRG has a relative weight that reflects the relative costliness of the inpatient treatment rendered for a patient in the specific group. Patient within the same MS-DRG group are expected to require a similar amount of hospital care and resources. To account for this potential variable, MS-DRG data was recorded from the financial data in Medicare patients. MS-DRG weight data was available in 28 and 18 patients in the TL and RS groups, respectively. Data Analysis Descriptive statistics were carried out to describe the characteristics of the study sample. Comparisons between the two surgery groups were performed using parametric and nonparametric methods, as appropriate. Comparison of two categorical variables was performed using chi-square analyses or Fisher s exact test. Differences in the nonparametric continuous data were compared using the Mann-Whitney U test or the Kruskal- Wallis test. Pearson correlation coefficients were obtained for relationships between continuous variables. For the cost TABLE II. Classification of Medical and Surgical Complications. Complications Major Minor Surgical Medical Hemorrhage CSF leak Wound infection Meningitis CPA hematoma Subdural hematoma Hydrocephalus Meningocele, pseudomeningocele Stroke Hemiparesis Pneumonia MI, A-fib DVT/PE CN VII deficit CN VIII deficit: vertigo, imbalance, HL, tinnitus Other CN deficit Wound dehiscence Headache Depression Elevated BP Memory loss Ataxia Electrolyte imbalance Other Complications were considered major when they had an impact on hospital stay. A-fib 5 atrial fibrillation; BP 5 blood pressure; CN 5 cranial nerve; CPA 5 cerebello-pontine angle; CSF 5 cerebrospinal fluid; DVT 5 deep vein thrombosis; MI 5 myocardial infarction; PE 5 pulmonary embolism. S7

4 TABLE III. Surgical and Medical Complications, Overall and Stratified to Tumor Size. All Tumor TL (n 5 43) RS (n 5 70) P* Surgical, major 2 (4.7) 10 (14.3) Surgical, minor 19 (44.1) 38 (54.2) Medical, major 1 (2.3) 7 (10.0) Medical, minor 1 (2.3) 2 (2.9) Lumbar drains 3 (7.0) 17 (24.6) 0.02 Size < 2cm (n 5 34) (n 5 33) Surgical, major 2 (5.9) 6 (18.2) 0.23 Medical, major 1 (2.9) 2 (6.1) 0.23 Size 2cm (n 5 9) (n 5 36) Surgical, major 0 (0.0) 4 (11.1) 0.30 Medical, major 0 (0.0) 5 (13.9) 0.30 Values in parentheses are percentages unless indicated otherwise. *Pearson v 2 test or Fischer s exact test. Significant value (P 0.05). RS 5 retrosigmoid; analysis, three dependent variables were considered: (1) ICU length of stay, (2) total hospital length of stay, and (3) total adjusted hospital cost. The main independent variable was the type of surgery. Other independent variables included the demographics and tumor size. Unadjusted associations were determined between the three dependent variables and the set of independent variables separately. Due to the small sample sizes, no adjusted multivariable regression analyses were performed. Instead, the variables that were significant at the univariate level and associated with the main independent variable were further investigated through stratified analyses. The criterion for statistical significance was set at P 0.05, two-tailed. Statistical analyses were performed using SPSS version 21 for Windows. TABLE IV. Total Hospital and Intensive Care Unit Length of Stay in Patients Without Any Complications and Without Any Major Complications. Without Any Complications LOS (days)* TL RS P All tumors (n 5 23) (n 5 26) Total hospital < ICU Without Major Surgical or Medical Complications LOS (days)* TL RS p T All tumors (n 5 40) (n 5 58) Total hospital < ICU *Values are mean 6 standard deviation. Mann-Whitney U test. Significant value (P 0.05). ICU 5 intensive care unit; LOS 5 length of stay; RS 5 retrosigmoid; TABLE V. Total Hospital and Intensive Care Unit Length of Stay Stratified by Tumor Size. LOS (days)* TL RS P All tumors (n 5 43) (n 5 70) Total hospital < ICU Size < 2cm (n 5 34) (n 5 33) Total hospital < ICU Size 2cm (n 5 9) (n 5 36) Total hospital ICU *Values are mean 6 standard deviation. Mann-Whitney U test. Significant value (P 0.05). ICU 5 intensive care unit; LOS 5 length of stay; RS 5 retrosigmoid; RESULTS Complications, Tumor Size, and Hospital LOS (Tables III, IV, and V) Major surgical complications were present in 4.7% and 14.3% of patients in the TL and RS groups, respectively (P ). Compared to one patient (2.3 %) in the TL group, seven patients (10 %) in the RS groups had a major medical complication (P ). In the TL group, both patients who had a major surgical complication had tumors < 2 cm compared to six (18.2 %) patients in the RS group. None of the patients with a tumor 2cmin the TL group had a major medical or surgical complication. In the RS group, four (11.1 %) and 5 (13.9 %) patients with tumors 2 cm had a major surgical or medical complication, respectively (P ). In the TL group, three patients (7.0 %) had a lumbar subarachnoid drain (LD) placed in the postoperative period. In the RS group, 17 (24.6 %) of patients had a LD placed (P ). The total hospital LOS was days in the TL group and days in the RS group (P < 0.001). The total LOS in ICU was days in the TL group and days in the RS group (P ). When patients were stratified by absence of any complications or any major complications, medical or surgical, the total hospital LOS remained significantly greater in the RS group (P < 0.001). There was no difference in the total ICU LOS. When patients were stratified by tumor size < and 2 cm, the total hospital LOS remained significantly greater in the RS group (P < 0.001). There was no difference in the total ICU LOS. Cost Analysis (Tables VI, VII, and VIII) Financial data was available for 37 patients in the TL group and 50 patients in the RS group. The mean adjusted total hospital cost in the TL group was $16, ,724 (range $9,433 37,992) and in the RS group was $25, ,765 (range $11, ,429) (P < 0.001). The MS-DRG weight was in the TL group and in the RS group (P ). In patients with tumors < 2 cm, the mean adjusted total hospital cost was $15, ,903 in the TL group and $19, ,317 in the RS group (P < 0.001). In patients with tumors 2 cm, the mean total adjusted hospital cost was $23, ,351 in the TL group and $29, ,745 in the RS S8

5 TABLE VI. Adjusted Cost Analysis for All Patients Who Underwent Translabyrinthine or Retrosigmoid Acoustic Neuroma Resection. TL (n 5 37) RS (n 5 50) P* Age (year) Total LOS (days) < Major complication 3 (8.1) 14 (28.0) 0.050, Minor complication 20 (54.1) 38 (76.0) Total adjusted cost $16, ,724 $25, ,968 < (n 5 28) (n 5 18) MS-DRG weight Values in parentheses are percentages unless indicated otherwise. Major and minor complications include both surgical and medical problems. Total adjusted cost: according to 2013 inflation rates in US dollars. *Mann-Whitney U test. Values are mean 6 standard deviation. v 2 test or Fischer s exact test. Significant value (P 0.05). LOS 5 length of stay; MS-DRG 5 Medicare severity-diagnosis related groups; RS 5 retrosigmoid; group (P ). In patients without complications (Table VIII), the mean adjusted total hospital cost for tumors < 2 cm in the RS group remained significantly greater than the TL group, $14, ,802 and $19, ,916, respectively (P ). However, in tumors 2 cm, there was no significant difference in total cost. Patient Disposition (Table IX) All patients in the TL group were discharged home or to residence, whereas 17.2 % of patients in the RS group were discharged to a skilled nursing facility or SNF. Seven patients in the RS group were readmitted for related issues within 30 days of discharge, whereas none of the patients in the TL group had a 30-day readmission (P ). Adjuvant radiotherapy was needed in 2.3% of patients in the TL group and 14.3% of patients in the RS group (P ). TABLE VII. Adjusted Cost Analysis for All Patients Undergoing Translabyrinthine or Retrosigmoid Acoustic Neuroma Resection Stratified by Tumor Size. TL RS P* Tumor Size < 2cm (n 5 30) (n 5 21) ICU LOS (day) 1.0 (0.3) 1.2 (0.5) Total LOS (day) 2.6 (1.3) 3.5 (1.5) < Total cost 15, ,903 19, < Tumor size 2cm (n 5 7) (n 5 28) ICU LOS (day) 1.4 (0.8) 1.8(1.4) Total LOS (day) 2.6 (0.8) 5.0 (4.6) Total cost 23, ,351 29, , Values in parentheses are percentages unless indicated otherwise. Total adjusted cost: according to 2013 inflation rates in US dollars. *Mann-Whitney U test. Significant value (P 0.05). ICU 5 intensive care unit; LOS 5 length of stay; RS 5 retrosigmoid; TABLE VIII. Adjusted Cost Analysis for Patient Without Complications Undergoing Translabyrinthine or Retrosigmoid Acoustic Neuroma Resection Stratified by Tumor Size. TL RS P* Tumor Size (n 5 15) (n 5 10) < 2cm ICU LOS (day) 1.0 (0.0) 1.0 (0.0) Total LOS (day) 2.1 (0.5) 3.2 (0.6) < Total cost 14, , Tumor Size (n 5 4) (n 5 10) 2cm ICU LOS (day) 1.0 (0) 1.5(1.1) Total LOS (day) 2.3 (0.5) 3.2 (1.4) Total cost 21, , , , Total adjusted cost: according to 2013 inflation rates in US dollars. *Mann-Whitney U test. Significant value (P 0.05). ICU 5 intensive care unit; LOS 5 length of stay; RS 5 retrosigmoid; Factors Independently Affecting Total Hospital and ICU LOS and Total Adjusted Cost (Table X) When accounting for demographics, tumor size, preoperative health status, and presence of postoperative complications, the RS approach was independently associated with increased total (P < 0.001) and ICU LOS (P ), and total adjusted hospital cost (P < 0.001). A greater ASA score, tumor size and MS-DRG weight were associated with significantly higher total and ICU LOS, and a higher adjusted total hospital cost. The presence of major complications was associated with increased total LOS (P ) and total adjusted hospital cost (P ). DISCUSSION Commonly, publications regarding AN are focused on the selection of the treatment modality: watchful waiting, microsurgery or radiosurgery, 3 5,14 neural outcome, 6 8 and the incidence of postoperative complications, 7 making less emphasis on the cost effective practice of medical care. In the year 2014, the total health care cost in the United States is projected to reach $3.09 trillion, 18.2% of the gross domestic product (GDP), and it is projected to rise reaching 19.9 % of the TABLE IX. Disposition and Additional Factors Not Accounted for in Total Adjusted Cost of All Patients Who Underwent Translabyrinthine or Retrosigmoid Acoustic Neuroma Resection. TL (n 5 43) RS (n 5 70) P* Discharge: home 43 (100) 58 (82.8) Discharge: SNF 0 (0.0) 12 (17.2) day readmission 0 (0.0) 7 (10.0) Adjuvant radiation 1 (2.3) 10 (14.3) Values in parentheses are percentages unless indicated otherwise. *v 2 test or Fischer s exact test. Significant value (P 0.05). RS 5 retrosigmoid; SNF 5 skilled nursing facility; TL 5 translabyrinthine. S9

6 TABLE X. Unadjusted Associations Between Independent Variables and Three Dependent Variables (ICU LOS, Total LOS, and Total Adjusted Cost). ICU LOS Total LOS Total Adjusted Cost Surgery P T * P T < 0.001* P T < 0.001* Gender P T P T P T Hearing class P k P k P k Age r , P r , P r , P BMI r , P r , P r , P ASA r , P < 0.001* r , P * r , P * Tumor size r , P < 0.001* r , P * r , P < 0.001* MS-DRG weight r , P < 0.001* r , P < 0.001* r , P < 0.001* Major complications P P * P * Minor complications P P * P Hearing classification according to the Committee on Hearing and Equilibrium 1995 guidelines. For age, BMI, ASA, and tumor size: Pearson s correlation. P T: Mann-Whitney U Test, P k : Kruskal-Walli. *Significant value (P 0.05). Major and minor complications included both medical and surgical versus none. ASA: American Society of Anesthesiologists; BMI: body mass index; ICU 5 intensive care unit; LOS 5 length of stay; MS-DRG: Medicare severitydiagnosis related groups. total GDP by the year Recovering economic conditions, the Affordable Care Act coverage expansions, and the aging population is projected to drive faster growth in health spending in 2014 and beyond. Under the current economic circumstances, opportunity cost and national debt make cost effectiveness a preponderant factor to consider in the decision algorithm of medical care. In this study, we find that the surgical approach used when excising AN has a direct impact on hospital stay, complications, and consequently on the total cost of care. To our knowledge, no study has analyzed the cost of hospitalization based on the individual surgical approaches: retrosigmoid versus translabyrinthine craniotomy. Nevertheless, several surveys have analyzed the hospital LOS and overall hospital cost based on the hospital volume, complications rates, socioeconomic status, advanced age, and patient s comorbidities. 9,10,16 Lower hospital volume, poorer socioeconomic status, advanced age, and increased comorbidities were associated with higher hospital LOS and total cost. The diagnosis and treatment of acoustic neuromas (AN) has changed considerably throughout the last 30 years. 2,5 There is a growing trend toward conservative management and stereotactic radiosurgery. 3,5,14,17,18 Nevertheless, in cases when surgery has been chosen as the treatment method, the selection guidelines for the surgical approach that will best benefit the patients outcome can occasionally be ambiguous because several techniques can be used in similar situations. 3,8,19 In the present study, we found that the total hospital LOS, ICU LOS, and adjusted total hospital cost were significantly higher in the RS group compared to the TL group, hence refuting our null hypothesis. We also found that the type of surgical approach, poorer health status, tumor greater or equal to 2 cm, and a higher MS-DRG were independently associated with a higher adjusted total hospital cost, hospital, and ICU LOS. Although the presence of complications, medical or surgical, was not S10 associated with a higher ICU LOS, it independently resulted in a higher hospital LOS. Major complications were associated with a higher adjusted total hospital cost. Currently, cranial nerve injuries and CSF leak are the most frequently described postoperative complications following AN surgery. 7 The impact that complications have on LOS and total cost of care varies significantly, making essential to consider these factors when comparing outcomes between surgical approaches. 11 Complications In this study, complications were divided in two groups: major and minor, taking into account their impact on total LOS. When combined, there were more major medical and surgical complications in the RS compared to the TL group (P ). When surgical and medical complications were analyzed separately, there was no significant difference in the incidence of major and minor complications between both groups. Although the presence of major complications did not significantly affect the total ICU LOS, it did independently increase the total hospital LOS (P ) and total adjusted hospital cost (P ). In addition, when complications and specifically major complications were absent, the total hospital LOS remained greater in the RS group. It appears that the majority of complications that occurred following the surgical procedure did not require an extension of the ICU stay but rather increased the total hospital stay. There were more lumbar subarachnoid drains placed in the RS compared to the TL group. These drains were at times introduced preoperatively at the surgeon s discretion or placed for treatment of a postoperative CSF leak (incisional or rhinorrhea) or pseudomeningocele. At our institution, lumbar drains are managed in a stepdown unit and kept for 3 days on average, potentially influencing the total cost of care and hospital LOS. This may prove to be an important aspect to be taken into account when evaluating treatment options.

7 Tumor Size The overall duration of hospital and ICU stay for patients who underwent a RS approach was considerably superior to TL approach. Patients with tumors less than 2 cm who underwent a RS had a higher total LOS and adjusted hospital cost. Interestingly, when tumors greater or equal to 2 cm were compared between both groups, there was a significant difference in total LOS but not in total cost. However, independently, tumor size was associated with greater total LOS and hospital cost. Sanna et al. 7 found similar results when comparing surgical approaches and LOS in tumors less or equal to 1 cm. In his series, the LOS for RS approach was days, significantly higher than the hospitalization days for the TL approach. In larger tumors with significant CPA involvement, the surgical operative time is increased, as well as the likelihood of postoperative surgical complications due to direct manipulation and more extensive dissection of the neurovascular structures associated with the tumor. The incidence of cerebellar edema, microvascular ischemia and bleeding are increased. In the subgroup with tumors greater than 2 cm, the increase in the total adjusted hospital cost was not commensurate with the total hospital LOS. The small number of patients in this subgroup who underwent a TL approach may explain this result. Hospital and ICU Length of Stay The total adjusted cost of care proved to be directly proportional to the LOS, averaging $25, ,765 for the RS approach and $16, ,724 when the TL approach surgery was selected as the treatment method. Cost data obtained from our institution s Web site and based on January 1, 2014, billing showed that the cost of a day was $5,720 in the neurosurgical ICU and $2,395 in the step-down unit. With the rise of accountable care organizations (ACO) aiming at reduced growth of health care cost through improvement in the quality of care delivered, these metrics gain more significance. Payment under the acute IPPS accounts up to 25% of Medicare payment and 20% of hospital s overall revenues. 12,13,20,21 Inpatient prospective payment system pays per-discharge rates based on the national base payment rates covering operating and capital expenses. These rates are then adjusted to the patient s condition and related treatment, and to the market s regional conditions. To account for the patient s needs, Medicare assigns discharges a weight factor, which is known as MS-DRG (Medicare severity diagnosis related groups). 13,22 This relative weight reflects the expected cost of the inpatient care delivered to patients in that specific MS-DRG group by reasonably efficient providers furnishing high quality care. The MS-DRG is influenced by three patient s characteristics: principal diagnosis (initial diagnosis requiring the inpatient care), procedure or procedures performed during the hospital stay, and complications and comorbidities. Medicare severity diagnosis related groups data was available for 28 patients in the TL group and for 18 in the RS group, in part because it was relatively recently implemented as a payment metric and recorded for the subgroup of patients on Medicare. The MS-DRG was significantly higher in the RS compared to the TL group. Because it is inherently related to the complications and comorbidities, it is not surprising that an association was present between higher MS-DRG weights and increased hospital and ICU LOS, and total cost. This increased value not only reflects increased complexity and cost, but when the same pathological condition, in this case AN, is being treated with two different approaches, the treatment strategy with a higher MS-DRG weight may be viewed as unfavorable from an ACO metric standpoint. Extrapolating this to non-medicare patients, it becomes more evident that the choice of the approach may have significant implications on the overall hospital cost and care delivered. Discharges to a skilled nursing facility and readmission within 30 days of surgery were significantly higher in the RS compared to TL approach. The average cost per day at a skilled nursing facility is $1,785, and the average cost of evaluation by a physical therapist is $374, with subsequent $120 billed for 15 minutes therapeutic activities. Although not taken into consideration for the compilation of final costs in this study, they should be considered as contributors in long-term cost analysis. 19,21 In the RS group, 10 patients required adjuvant radiotherapy to treat residual tumor compared to one patient in the TL group (P ). This cost accrued over time by additional surveillance MRIs substantially increases the total cost unaccounted for in the initial hospital cost. 23 Study Limitations There are a number of limitations to this study. A significant limitation of this study is the relatively small number of patients. In addition, the retrospective design creates an allocation bias. It appears that the RS group had a higher number with tumors larger or equal to 2 cm. Because tumor size was found to be an independent factor associated with increased LOS and total cost, a confounding bias might be present. Similarly, size may have been a confounding factor, resulting in a higher percentage of patients in the RS group requiring adjuvant radiotherapy. Finally, the classification of the complications into major and minor was based on a presumed impact on hospital stay. The potential impact of each complication on LOS was not individually analyzed to assess the validity of that classification. Nevertheless, based on clinical knowledge and experience, this classification was not arbitrarily selected. Although the findings in this study are not intended to modify the surgical selection criteria, the economic findings presented herein should weight in on the surgeon s decision algorithm. Although hearing preservation and surgeon s experience is not a decisive factor, we propose that patients with comorbidities and larger tumors be considered for a TL approach. CONCLUSION We found that hospital and ICU LOS, and adjusted total hospital costs, are significantly less for patients undergoing translabyrinthine acoustic neuroma resection compared to the retrosigmoid approach. Many S11

8 factors account for these differences. Greater tumor size, poorer health status, comorbidities, and development of complications were associated with higher LOS and hospital cost. Economic considerations, in addition to tumor characteristics and surgeon s preference, should be considered in the surgical treatment planning of patients with acoustic neuroma. Acknowledgments We thank Dr. Souha Fares for her assistance in the statistical analysis of the data and Dr. Pierre Lavertu for his critical review of the article. Author Contributions: Study concept and design: M.T.S., C.A.M. Acquisition of data: J.G.S., R.L.C. Interpretation of data: M.T.S., C.C.W., K.J.K. Drafting of manuscript: M.T.S., C.C.W., K.J.K. Critical revision of manuscript: M.T.S. Statistical analysis: S.F. Study supervision: M.T.S., C.A.M. BIBLIOGRAPHY 1. Tos M, Stangerup SE, Caye-Thomasen P, Tos T, Thomsen J. What is the real incidence of vestibular schwannoma? Arch Otolaryngol Head Neck Surg 2004;130: Stangerup SE, Caye-Thomasen P. Epidemiology and natural history of vestibular schwannomas. Otolaryngol Clin North Am 2012;45: Briggs RJ, Fabinyi G, Kaye AH. Current management of acoustic neuromas: review of surgical approaches and outcomes. J Clin Neurosci 2000; 7: Pollock BE. Vestibular schwannoma management: an evidence-based comparison of stereotactic radiosurgery and microsurgical resection. Prog Neurol Surg 2008;21: Theodosopoulos PV, Pensak ML. Contemporary management of acoustic neuromas. Laryngoscope 2011;121: Di Maio S, Malebranche AD, Westerberg B, Akagami R. Hearing preservation after microsurgical resection of large vestibular schwannomas. Neurosurgery 2011;68: Sanna M, Taibah A, Russo A, Falcioni M, Agarwal M. Perioperative complications in acoustic neuroma (vestibular schwannoma) surgery. Otol Neurotol 2004;25: Harsha WJ, Backous DD. Counseling patients on surgical options for treating acoustic neuroma. Otolaryngol Clin North Am 2005;38: Barker FG 2nd, Carter BS, Ojemann RG, Jyung RW, Poe DS, McKenna MJ. Surgical excision of acoustic neuroma: patient outcome and provider caseload. Laryngoscope 2003;113: Ahmed OH, Mahboubi H, Lahham S, Pham C, Djalilian HR. Trends in demographics, charges, and outcomes of patients undergoing excision of sporadic vestibular schwannoma. Otolaryngol Head Neck Surg 2014; 150: Sonig A, Khan IS, Wadhwa R, Thakur JD, Nanda A. The impact of comorbidities, regional trends, and hospital factors on discharge dispositions and hospital costs after acoustic neuroma microsurgery: a United States nationwide inpatient data sample study ( ). Neurosurg Focus 2012;33:E Centers for Medicare and Medicaid Services. Medicare program; changes to the hospital inpatient prospective payment systems and fiscal year 2008 rates. Fed Regist 2007;72: Rosenstein AH, O Daniel M, White S, Taylor K. Medicare s value-based payment initiatives: impact on and implications for improving physician documentation and coding. Am J Med Qual 2009;24: Gal TJ, Shinn J, Huang B. Current epidemiology and management trends in acoustic neuroma. Otolaryngol Head Neck Surgery 2010;142: Rice JJ, Harris DW. A proposal to reroute and reform the healthcare money trail. Am J Surg 2014;207: Slattery WH, Schwartz MS, Fisher LM, Oppenheimer M. Acoustic neuroma surgical cost and outcome by hospital volume in California. Otolaryngol Head Neck Surg 2004;130: Babu R, Sharma R, Bagley JH, Hatef J, Friedman AH, Adamson C. Vestibular schwannomas in the modern era: epidemiology, treatment trends, and disparities in management. J Neurosurg 2013;119: Patel J, Vasan R, Van Loveren H, Downes K, Agazzi S. The changing face of acoustic neuroma management in the USA: analysis of the 1998 and 2008 patient surveys from the acoustic neuroma association. Br J Neurosurg 2014;28: Banerjee R, Moriarty JP, Foote RL, Pollock BE. Comparison of the surgical and follow-up costs associated with microsurgical resection and stereotactic radiosurgery for vestibular schwannoma. J Neurosurg 2008;108: Emanuel E, Tanden N, Altman S, et al. A systemic approach to containing health care spending. N Engl J Med 2012;367: Centers for Medicare and Medicaid Services. Medicare program; prospective payment system for long-term care hospitals RY 2009: annual payment rate updates, policy changes, and clarifications; and electronic submission of cost reports: revision to effective date of cost reporting period. Final rule. Fed Regist 2008;73: McNutt R, Johnson TJ, Odwazny R, et al. Change in MS-DRG assignment and hospital reimbursement as a result of Centers for Medicare & Medicaid changes in payment for hospital-acquired conditions: is it coding or quality? Qual Manag Health Care 2010;19: Verma S, Anthony R, Tsai V, Taplin M, Rutka J. Evaluation of cost effectiveness for conservative and active management strategies for acoustic neuroma. Clin Otolaryngol 2009;34: S12