Cost: Which Costs More, Open or Minimally Invasive Surgery?

23 Cost: Which Costs More, Open or Minimally Invasive Surgery?

MIS: Matthew J. McGirt
Open: Scott L. Parker

23.1 Introduction

The current growth in health care cost is unsustainable. Current health care costs are nearly 18% of the U.S. gross domestic product (GDP), with the cost of surgical care alone comprising approximately 7% of GDP.1 Without reform, health care costs are expected to surpass half of the U.S. GDP within the next few decades. As a result, cost–utility and other forms of value analyses are becoming central aspects of health care reform initiatives. At the heart of this evidence-driven reform process is safety, effectiveness, and cost of care, each of which affects the value of healthcare. To improve the efficiency and reduce the cost of health care delivery, value-based purchasing has emerged as a payment methodology that rewards quality of care. In value-based purchasing, providers are held accountable for both the quality and the cost of the health care services they provide. As we move forward, it will become standard that more costly medical treatments are required to prove their value by demonstrating a health benefit that is greater than its added cost. To achieve a sustainable health care system, reform strategies ranging from bundled payments to accountable care organizations aim to eliminate or minimize the purchasing of low value or cost-ineffective care.

When interpreting cost and value, it is imperative to consider the perspective of the stakeholder or the decision maker. In a complex medical market, the perspective will define the health care consumer and the provider. Cost to a payer may represent profit to a hospital system. Added cost to a hospital may not translate to added cost to the payer or health care system, but merely a decreased profit to the hospital. The preferred perspective for U.S. health care policy remains the societal perspective. From the societal perspective, both direct costs (all health care expenditures) and indirect costs (occupational productivity losses of patient and caregivers) are considered. From the hospital perspective, only the hospital’s direct costs are concerned, which represent the expenditures of the hospital to deliver care rather than their billing or payment from the payer.

23.2 Cost-Related Advantages of Minimally Invasive Technique

Minimally invasive approaches for spine surgery have many theoretical cost advantages. The concept that the greatest variability in cost lies within operating room expenses and implant costs is a common misunderstanding. Growing evidence suggests that by far the greatest variability in surgical cost lies within the post–acute care episode, in the immediate days to weeks following hospital discharge after surgery.2,3,4,5,6,7 It is during this post–acute care episode that the potential value of minimally invasive technologies is greatest. Length of hospital stay, surgical complication, hospital readmission, acute need for reoperation (infection, hematoma, etc.), and need for inpatient rehab or skilled nursing care are significant factors that can greatly reduce cost in the post–acute care episode. Any technology or surgical approach which can reduce the prevalence of any of these events will have a dramatic effect on direct health care cost. Much of these costs are currently the burden of third-party payers; however, with emerging health care payment models, these risks and cost variables are increasingly shifting to the hospital. With more vertical alignment of hospitals and payers in the near future, the theoretical cost benefits of minimally invasive surgery will benefit both stakeholders: hospital and payer. Finally, lost occupational productivity is a significant variable in cost which is largely the burden of health care purchasers, employers, and policymakers. Minimally invasive approaches theoretically allow for a quicker recovery during the post–acute care episode, which may allow for accelerated return to work and reduced indirect costs. The minimally invasive surgery (MIS) value question, which only evidence can answer, is whether the greater upfront operating room costs of MIS are offset by downstream cost reduction benefits. The following section will summarize the evidence to date to help answer this question.

23.3 Cost-Related Advantages of Open Technique

The open techniques for spine surgery are well known to the vast majority of practicing spine surgeons. These techniques have a long track record and provide an effective tool for the treatment of a variety of spinal disorders. An advantage of the open technique is avoidance of the steep learning curve needed to master the MIS approaches, as there is an increased risk for complications during these initial cases. This is important given surgical complications can be a primary driver of increased health care resource utilization in the postoperative period. Finally, due to the lack of anatomic landmarks necessary for placing pedicle screws, the use of MIS technology necessitates a significant amount of radiation exposure via fluoroscopy for both the patient and the surgical team. The use of open surgical techniques and anatomic landmarks for spinal instrumentation has been shown to result in a high success rate of accurately placed pedicle screws.8

23.4 Case Illustration

The following case illustration is a representative population-based example of outcomes and associated costs expected following MIS versus open transforaminal lumbar interbody fusion (TLIF). The numbers used in this case illustration are based on estimations of the published literature to date.

23.5 Minimally Invasive Surgery

In Practice A, 100 patients undergo MIS-TLIF ( Table 23.1). The mean length of postoperative hospital stay was 3 days. The mean total in-hospitalization cost for these patients was $23,000. It is important to note that each 1-day reduction in length of stay results in a direct cost savings of $1,500. The mean length of time to narcotic independence was 3 weeks and the mean time to return to work was 7 weeks ( Fig. 23.1). By 3 months postoperatively, cerebrospinal fluid leak occurred in seven patients. One patient experienced a surgical site infection requiring operative intervention and long-term antibiotics. Patient-reported pain, disability, and quality of life significantly improved from baseline status ( Fig. 23.2).

Two years postoperatively, significant improvement in patient-reported outcomes was maintained. For this patient population, mean total direct costs were $30,000 (including costs of surgery, hospitalization, health care visits, diagnostic imaging, and medications). Total indirect cost (comprising time of missed work and caregiver hours) was $10,000. Consequently, the total health care cost (direct and indirect) associated with MIS-TLIF at 2 years was $40,000.

23.6 Open Surgery

In Practice B, 100 patients with similar demographic, comorbid, and socioeconomic backgrounds to those in Practice A undergo open-TLIF, Table 23.1. The mean length of postoperative hospital stay was 4 days. The mean total in-hospitalization cost for these patients was $25,000. The mean length of time to narcotic independence was 9 weeks and the mean time to return to work was 11 weeks ( Fig. 23.1). By 3 months postoperatively, cerebrospinal fluid leak occurred in 5 patients. Four patients experienced a surgical site infection requiring operative intervention and long-term antibiotics. Patient-reported pain, disability, and quality of life significantly improved from baseline status ( Fig. 23.2).

Two years postoperatively, the significant improvement in patient-reported outcomes was maintained. For this patient population, mean total direct costs were $34,000 (including costs of surgery, hospitalization, health care visits, diagnostic imaging, and medications). Total indirect cost (comprising time of missed work and caregiver hours) was $18,000. Consequently, the total health care cost (direct and indirect) associated with open-TLIF at 2 years was $52,000.

23.7 Discussion of Minimally Invasive Surgery

23.7.1 Level I Evidence in Minimally Invasive Surgery

There are currently no level I studies available that assess cost for MIS versus open spine surgery.

23.7.2 Level II Evidence in Minimally Invasive Surgery

While there have recently been several prospective cohort studies comparing minimally invasive versus open spine surgery reported in the literature, only a few studies evaluate the health care resource utilization and costs associated with these procedures.

The largest cost comparison study to date compared 50 consecutive MIS and 50 consecutive open-TLIF patients at a single institution.7 The authors reported similar improvement in patient-reported outcome metrics for the two techniques at both short-term (3-month) and long-term (24-month) followups. MIS versus open-TLIF was associated with a 1-day decrease in hospital stay which correlated into a mean hospital cost reduction of $1,758 per case. In this study, measures of surgical quality (morbidity, readmission, and reoperation) and 2-year resource use were similar between the two cohorts, resulting in similar overall direct health care costs for MIS and open-TLIF: $27,621 ± 6,107 versus $28,442 ± 6,005; p = 0.50. However, for patients employed preoperatively, the mean time to return to work was accelerated in patients undergoing MIS-TLIF, resulting in a reduction of the indirect cost by almost half for MIS versus open-TLIF: $10,942 ± 9,102 versus $19,416 ± 22,727; p = 0.06. This led to significantly reduced total (direct + indirect) cost for MIS versus open-TLIF: $38,563 ± 10,594 versus $47,858 ± 20,148; p = 0.03. It is important to appreciate the various perspectives from which cost saving was demonstrated in this study. Due to the reduction in length of stay, MIS surgery was able to provide cost savings from the hospital perspective. Because surgical quality and resource utilization were similar for each cohort, from the payer perspective (direct cost only), there was no difference in cost for MIS versus open-TLIF. Finally, because of the reduced indirect cost associated with an accelerated return to work after MIS-TLIF, MIS surgery also represented a cost saving technology from the societal perspective (total cost, direct + indirect).

Fig. 23.1 Case illustration example. Kaplan– Meier graph demonstrating reduced time to narcotic independence and return to work for patients undergoing MIS versus open-TLIF.