Laparoscopic Inguinal Hernia Repair: Undervalued by the Relative Value Unit System

Introduction

Now, a mainstay for determining physician reimbursement, relative value units (RVUs), was originally developed to measure clinical productivity and intensity of work. RVUs incorporate 3 fundamental components—physician work, practice expense, and malpractice insurance.^1-3 As the fee-for-service health care model transitioned to a relative value scale in 1992, the Centers for Medicare & Medicaid Services introduced a Resource-Based Relative Value Scale and the American Medical Association’s Relative Value Update Committee (RUC) was developed.^1,4-7 The RUC is composed of 31 members representing over 20 subspecialties who drive RVU determinations based primarily on survey data of physicians. Response rates to such surveys are typically low (median 2.2%), and thus, RUC decisions are often driven by the perspectives of a limited sample of providers.^2,4

There is limited existing literature ascertaining differences in RVUs based on approach of inguinal hernia repair and whether the current compensation model of RVUs appropriately accounts for the technical complexity and surgical training required for laparoscopic repair as compared to open. Therein lies a gap in understanding whether RVUs appropriately value the complexity of an inguinal hernia repair not only just based on operative length or surgical technique utilized but also taking the underlying patient factors, comorbidities, and complexity of the hernia into account.

Alongside the onset of RVUs, Current Procedural Terminology (CPT) was developed to standardize coding and reimbursement for physician services.^2,8 CPT codes for hernia repair were revised in 1994 to account for type of hernia, patient age, patient presentation (initial or recurrent), clinical presentation (reducible, incarcerated or strangulated), and method of repair (open or laparoscopic). ⁸ The objective of this study is to evaluate how effectively RVUs capture the work effort, complexity, technical skill, and postoperative care required of laparoscopic vs. open inguinal hernia repair.

Methods

This study was approved as a nonhuman subject study by the Institutional Review Board of the Lundquist Institute at Harbor-UCLA. The American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP) database from 2012 to 2017 was used. The NSQIP is a nationally validated program for assessing risk-adjusted surgical outcomes with the goal of improving quality of surgical care. The NSQIP database collects data from more than 708 hospitals in the United States and provides information about patient demographics, comorbidities, preoperative risk factors, operative details, and postoperative 30-day outcomes.

All patients who underwent a single procedure of open (CPT codes 49505, 49507, 49520, and 49525) or laparoscopic (CPT codes 49650 and 49651) inguinal hernia repair who had a diagnosis of inguinal hernia as identified by International Classification of Diseases (ICD9 and ICD10) diagnosis codes were included. Additionally, the hernia types were further categorized as unilateral vs. bilateral, obstructed vs. non-obstructed based on ICD9 and ICD10, and primary vs. recurrent based on the CPT code.

Patient demographics including age, gender, race and ethnicity, body mass index, American Society of Anesthesiologists class, and preoperative comorbidities including diabetes, hypertension, congestive heart failure, smoking status, preoperative ventilation, chronic obstructive pulmonary disease, ascites, dialysis, acute kidney injury, bleeding disorder, preoperative sepsis, history of wound infection, and emergent procedure were extracted.

Primary outcome measures included work relative value units (wRVUs), wRVUs per minute, and total operative times, defined as operation start (incision) to end time.

Statistical analyses were performed using SPSS, version 24.0 (IBM Corp, Armonk, New York), and coarsened exact matching (CEM) for SPSS. Two-sided P < .05 was considered statistically significant. Student’s t-test was used to compare continuous data, and Pearson’s chi-square and Fisher’s exact tests were used to compare categorical data as indicated. Data were compared as aggregate and matched cohorts. Since there were statistically significant differences between the preoperative risk factor for open and laparoscopic groups (Table 1) and in order to reduce the selection bias due to inherent clinical differences, CEM with the K:K method was used to match the 2 groups. Additionally, a linear regression model was used to regress wRVUs over 3 hernia-related variables such as laterality (unilateral vs. bilateral), obstruction (obstructed vs. non-obstructed), and type of hernia (primary vs. recurrent), in addition to other factors that can potentially affect RVU such as operative time, hospital length of stay (LOS), complications, readmission, and reoperation rates in open repair (OIHR). Based on the beta coefficients and constant in this model, a formula was created to calculate wRVUs for laparoscopic inguinal hernia repair (LIHR). Paired-sample t-test was used to compare calculated and assigned wRVUs for each case.

Table 1.

Comparison of Patient Characteristics for Open vs. Laparoscopic Inguinal Hernia Repair: Aggregate and Matched Cohorts.

Abbreviations: COPD, chronic obstructive pulmonary disease; CHF, congestive heart failure; ASA, American Society of Anesthesiologists; BMI, body mass index; SD, standard deviation; HTN, hypertension; AKI, acute kidney injury.

a

Diabetes mellitus with oral agents or insulin.

b

Current smoker within 1 year.

c

History of severe chronic obstructive pulmonary disease.

d

History of congestive heart failure in 30 days before surgery.

e

Hypertension requiring medication.

f

Open wound/wound infection.

Results

In the aggregate cohort, a total of 139 275 patients were included, of which 99 176 (71.2%) patients underwent open inguinal hernia repair and 40 099 (28.8%) laparoscopic repair. From each group, 38 076 patients were matched and included in the matched cohort. A comparison of patient demographics and clinical characteristics is demonstrated in Table 1. No significant differences in preoperative demographics and comorbidities remained from the aggregate cohort after matching.

Mean wRVUs, mean wRVUs per minute, and mean operative times were compared for 8 hernia type categories (unilateral vs. bilateral; obstructed vs. non-obstructed; primary vs. recurrent; 2 × 2 × 2 = 8) and results are reported in Table 2. In both aggregate and matched cohorts, mean wRVUs for LIHR were significantly lower than OIHR in all 8 categories (P < .001). Mean wRVUs per minute was lower for LIHR in 7 categories in the aggregate cohort (P < .005) and in 6 categories in the matched cohort (P < .001). This difference was more prominent in the unilateral groups, considering the rate of laparoscopic approach in unilateral repair increased from 20% to 29.6% (P < .001) over the study period. Operative times comparing laparoscopic and OIHR across the 8 categories were not clinically different.

Table 2.

Comparison of Mean wRVUs, RVU/min and Operative Times by Inguinal Hernia Type and Operative Modality: Aggregate and Matched Cohorts.

Abbreviations: Op Time, total operative time; RVU, relative value units; wRVU, work RVU; NS, not statistically significant.

Based on the regression model, the calculated RVU was created using the following formula:

Calculated RVU = 7.932 + (.001 × Operative time) + (.001 × LOS) + (2.122 × Recurrent) + (.45 × Unilateral) + (.91 × Obstruction) + (.034 × Readmission) + (.28 × Reoperation).

In both aggregate and matched cohorts, on average, wRVUs assigned to laparoscopic cases were undervalued by 2.05 units compared to calculated wRVUs (Table 3). The lowest difference between the 2 belonged to bilateral, primary, and non-obstructed IHR (1.65) and highest to unilateral, recurrent, and obstructed IHR (3.12).

Table 3.

Assigned vs. Calculated Mean RVUs and Mean Differences of RVUs Assigned to Laparoscopic Inguinal Hernia Repair.

Abbreviation: RVU, relative value units.

Discussion

Using a large, multicenter NSQIP database, this study demonstrates that current RVUs undervalue laparoscopic compared to open inguinal hernia repair across all clinical scenarios. Laparoscopic mean RVUs and mean RVUs per minute were consistently undervalued when compared to OIHR. These differences persisted despite matching patients for their preoperative risk factors and controlling for equivalent clinical scenarios (unilateral vs. bilateral, obstructed vs. non-obstructed, primary vs. recurrent inguinal hernias) and operative times. Such undervaluation assigned laparoscopic repair with 1.65 to 3.12 lower mean RVUs compared to an OIHR matched patient.

Only 2% of all procedures are reviewed or updated annually by the RUC, which has generated controversy especially given potential respondent bias. ⁴ RVUs guide nearly 70% of all physician payments in the United States accounting for $500 billion annually.^2,4 Existing literature has revealed that the RUC recommendations are often unreliable leading up to $400 million in payment discrepancies and that survey respondents’ estimates of recalled operative times are up to twice as long as actual operative time stamp data.^9,10 Such findings have given rise to calls for a more objective reflection of surgeons’ physical and mental effort, time, technical skill, judgment, and psychological stress in a productivity-driven health care system. ⁷

The only existing study to specifically evaluate RVUs for inguinal hernia repair was a NSQIP retrospective review of 134 391 patients from 2012 to 2017 by Doval et al. ¹¹ Recurrent inguinal procedures were found to have longer mean operative times and greater mean RVUs than primary repair (P < .0001). ¹¹ However, it is important to note this study excluded bilateral repairs and that laparoscopic, open, and incarcerated OIHRs were analyzed as separate cohorts. Thus, laparoscopic vs. open techniques were not directly compared which raises the question of whether recurrent LIHR is reimbursed to the same extent as recurrent OIHR.

There has been increasing attention drawn to the accuracy of RVUs as a reflection of surgical effort and to avoid such undervaluation of procedures like LIHR. Childers et al called for more objective work measures to assign RVUs by utilizing NSQIP data of median operative time, postoperative LOS, rate of readmission, and rate of reoperation to create a valuation model. ¹ Operative time and LOS were found to be stronger proxies of surgical complexity, yet there were many nuances in accurately capturing the intensity of a procedure. This study raised many questions regarding the need for more objective means to define RVUs, particularly given the availability of numerous national surgical databases. ¹²

Multiple studies have demonstrated an extensive pattern of undervaluation by the RVU system across surgical disciplines. Both Shah et al and Schwartz et al queried the NSQIP database to highlight such inconsistencies of RVUs as a reflection of surgeon productivity.^13,14 In a review of 11 high volume surgical cases among 14 481 patients, RVUs correlated poorly with metrics of LOS (R² = .05), operative time (R² = .10), and mortality (R² = .35). ¹³ Similarly, Schwartz et al demonstrated that RVUs assigned to emergent colorectal, hernia, and biliary procedures were equivalent to their elective counterparts. ¹⁴ Despite having longer hospital stays as well as higher readmission, reoperation, complication, and mortality rates, acute care patients were found to have RVUs similar to that of elective patients undergoing the same procedure. Schwartz et al suggested an emergent case modifier to account for the complexity or aftercare requirement of emergent cases. ¹⁴ In the realm of vascular surgery, Martin et al noted that longer open vascular procedures received fewer RVUs than endovascular cases, not accounting for the complexity of open approaches. ¹⁵

Sodhi et al have reported extensively on the undervaluation of surgical work by RVUs in the realm of orthopedic surgery where RUC recommendations for RVUs are derived from less than 160 physicians without any updates since 1995. ⁹ Revision total hip arthroplasty is inherently more technically challenging and with greater patient aftercare, yet Sodhi et al has demonstrated lower RVUs per minute for revision cases than primary repair counterparts (P < .001). ¹⁶ This $113 052 annual cost discrepancy for a more technically demanding procedure often requiring removal of a “well-fixed, sometimes even cemented, femoral or acetabular component” is somewhat analogous to the surgical effort required for mesh explantation in recurrent inguinal hernia cases. ¹⁶ Similarly, in other studies, revision total knee arthroplasty generated less RVUs than revision total hip arthroplasty (P < .001), ¹⁷ and revision total knee arthroplasty received lower reimbursement rates per minute than primary cases, despite more technical difficulty and longer operative times (P < .001). ¹⁸ Such patterns of RVU-based undervaluation of surgical work are pervasive across many surgical disciplines.

Limitations of the present study include the retrospective study design and inherent limitations of the NSQIP database. The NSQIP database is restricted to a small proportion of participating hospitals nationally. Additionally, the NSQIP database does not provide insight into all perioperative details such as hernia size, hernia contents, duration of symptoms, degree of obstruction or recurrence, chronicity of hernia pain, impact on quality of life, type of mesh used if any, and exact technique applied for hernia repair. Such factors impart even more inherent variability in the complexity of repair which may be unaccounted for when attempting to compare RVUs across open vs. laparoscopic approaches.

Conclusions

Our study demonstrates that current RVUs appear to value open inguinal hernia repair more than laparoscopic repair, suggesting that open inguinal repair is labor intensive. The most significant discrepancy when comparing assigned vs. calculated RVUs was among laparoscopic unilateral, recurrent, obstructed inguinal hernia repair which was most significantly undervalued. LIHR is potentially just one of many procedures which have been rendered as less valuable solely based on operative technique without considering the underlying patient and hernia characteristics that confer technical challenges. Future studies and conversation are warranted to continue to advocate for more objective determinants of surgical reimbursement which serve as a true proxy of surgeon’s physical and mental effort, technical skills, time, and psychological stress. An RVU-based compensation model is overdue to embrace the advent of an increasing minimally invasive surgical reality which heavily relies upon laparoscopic and robotic techniques.

NSQIP Disclosure

The ACS NSQIP and the hospitals participating in the ACS NSQIP are the source of the data used herein; they have not verified and are not responsible for the statistical validity of the data analysis or the conclusions derived by the authors.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.