Joseph S. Cheng

Utility of minimum clinically important difference in assessing pain, disability, and health state after transforaminal lumbar interbody fusion for degenerative lumbar spondylolisthesis

OBJECT Outcome studies for spine surgery rely on patient-reported outcomes (PROs) to assess treatment effects. Commonly used health-related quality-of-life questionnaires include the following scales: back pain and leg pain visual analog scale (BP-VAS and LP-VAS); the Oswestry Disability Index (ODI); and the EuroQol-5D health survey (EQ-5D). A shortcoming of these questionnaires is that their numerical scores lack a direct meaning or clinical significance. Because of this, the concept of the minimum clinically important difference (MCID) has been put forth as a measure for the critical threshold needed to achieve treatment effectiveness. By this measure, treatment effects reaching the MCID threshold value imply clinical significance and justification for implementation into clinical practice. METHODS In 45 consecutive patients undergoing transforaminal lumbar interbody fusion (TLIF) for low-grade degenerative lumbar spondylolisthesis-associated back and leg pain, PRO questionnaires measuring BP-VAS, LPVAS, ODI, and EQ-5D were administered preoperatively and at 2 years postoperatively, and 2-year change scores were calculated. Four established anchor-based MCID calculation methods were used to calculate MCID, as follows: 1) average change; 2) minimum detectable change (MDC); 3) change difference; and 4) receiver operating characteristic curve analysis for two separate anchors (the health transition index [HTI] of the 36-Item Short Form Health Survey [SF-36], and the satisfaction index). RESULTS All patients were available at the 2-year follow-up. The 2-year improvements in BP-VAS, LP-VAS, ODI, and EQ-5D scores were 4.3 ± 2.9, 3.8 ± 3.4, 19.5 ± 11.3, and 0.43 ± 0.44, respectively (mean ± SD). The 4 MCID calculation methods generated a range of MCID values for each of the PROs (BP-VAS, 2.1-5.3; LP-VAS, 2.1-4.7; ODI, 11-22.9; and EQ-5D, 0.15-0.54). The mean area under the curve (AUC) for the receiver operating characteristic curve from the 4 PRO-specific calculations was greater for the HTI versus satisfaction anchor (HTI [AUC 0.73] vs satisfaction [AUC 0.69]), suggesting HTI as a more accurate anchor. CONCLUSIONS The TLIF-specific MCID is highly variable based on calculation technique. The MDC approach with the SF-36 HTI anchor appears to be most appropriate for calculating MCID because it provided a threshold above the 95% CI of the unimproved cohort (greater than the measurement error), was closest to the mean change score reported by improved and satisfied patients, and was least affected by the choice of anchor. Based on the MDC method with HTI anchor, MCID scores following TLIF are 2.1 points for BP-VAS, 2.8 points for LP-VAS, 14.9 points for ODI, and 0.46 quality-adjusted life years for EQ-5D.

Comparative effectiveness of minimally invasive versus open transforaminal lumbar interbody fusion: 2-year assessment of narcotic use, return to work, disability, and quality of life.

Study Design Retrospective cohort comparison between minimally invasive (MIS) and open transforaminal lumbar interbody fusion (TLIF). Objective To assess 2 earlier unstudied endpoints (duration of narcotic use and return to work) and long-term pain, disability, and quality of life (QOL) for MIS-TLIF versus open-TLIF. Summary of Background Data MIS-TLIF for lumbar spondylolithesis theoretically allows for surgical treatment of back and leg pain while minimizing blood loss and tissue injury. Although earlier studies have shown shorter hospital stay and equivocal 6 and 24 month outcomes with MIS-TLIF versus open-TLIF, the effect of MIS techniques on postoperative narcotic use and return to work are poorly understood. Methods Thirty patients undergoing MIS-TLIF (n=15) or open-TLIF (n=15) for grade I degenerative spondylolithesis-associated back and leg pain were enrolled. Two-year outcomes were assessed through phone interview and it included pain [visual analog scale (VAS)], low-back disability (Oswestry disability index), EuroQol-5D, occupational disability, and narcotic use. Results MIS-TLIF versus open-TLIF cohorts were similar at baseline. Median [interquartile range (IQR)] length of hospitalization after surgery was significantly less for MIS-TLIF versus open-TLIF [3 (3 to 3) vs 5.5 (4 to 6) d], P=0.001. MIS-TLIF versus open-TLIF patients showed similar 2-year improvement in VAS for back pain, VAS for leg pain, Oswestry disability index, and EuroQol-5D scores. Overall, median (IQR) length of postoperative narcotic use was 3.0 (1.4 to 4.6) weeks and significantly shorter for MIS-TLIF versus open-TLIF patients [2.0 (1.0 to 3.0) vs 4.0 (1.4 to 4.6) wk, P=0.008]. Overall, median (IQR) time to return to work was 13.9 (2.2 to 25.5) weeks and significantly shorter for MIS-TLIF versus open-TLIF patients [8.5 (4.4 to 21.4) vs 17.1 (1.8 to 35.9) wk, P=0.02]. Conclusions Both MIS-TLIF and open-TLIF provide long-term improvement in pain, disability, and EuroQol-5D in patients with back and leg pain from grade I degenerative spondylolithesis. However, MIS-TLIF may allow for shortened hospital stays, reduced postoperative narcotic use, and accelerated return to work, reducing both direct medical costs and indirect costs of lost work productivity associated with TLIF procedures.

Post-operative infection after minimally invasive versus open transforaminal lumbar interbody fusion (TLIF): Literature review and cost analysis

INTRODUCTION Surgical site infection (SSI) in the setting of lumbar fusion is associated with significant morbidity and medical resource utilization. To date, there have been no studies conducted with sufficient power to directly compare the incidence of SSI following minimally invasive (MIS) vs. open TLIF procedures. Furthermore, studies are lacking that quantify the direct medical cost of SSI following fusion procedures. We set out to determine the incidence of SSI in patients undergoing MIS vs. open TLIF reported in the literature and to determine the direct hospital cost associated with the treatment of SSI following TLIF at our institution. METHODS A systematic Medline search was performed to identify all published studies assessing SSI after MIS or open TLIF. The cumulative incidence of SSI was calculated from all reported cohorts and compared between MIS vs. open TLIF. In order to determine the direct hospital costs associated with the treatment of SSI following TLIF, we retrospectively reviewed 120 consecutive TLIFs performed at our institution, assessed the incidence of SSI, and calculated the SSI-related hospital costs from accounting and billing records. RESULTS To date, there have been 10 MIS-TLIF cohorts (362 patients) and 20 open-TLIF cohorts (1 133 patients) reporting incidences of SSI. The cumulative incidence of reported SSI was significantly lower for MIS vs. open-TLIF (0.6% vs. 4.0%, p=0.0005). In our experience with 120 open TLIF procedures, SSI occurred in 6 (5.0%) patients. The mean hospital cost associated with the treatment of SSI following TLIF was

Cost-effectiveness of minimally invasive versus open transforaminal lumbar interbody fusion for degenerative spondylolisthesis associated low-back and leg pain over two years.

29,110 in these 6 cases. The 3.4% decrease in reported incidence of SSI for MIS vs. open-TLIF corresponds to a direct cost savings of

Minimally Invasive versus Open Transforaminal Lumbar Interbody Fusion for Degenerative Spondylolisthesis: Comparative Effectiveness and Cost-Utility Analysis

98,974 per 100 MIS-TLIF procedures performed. CONCLUSIONS Post-operative wound infections following TLIF are costly complications. MIS vs. open TLIF is associated with a decreased reported incidence of SSI in the literature and may be a valuable tool in reducing hospital costs associated with spine care.

Anticoagulation risk in spine surgery.

OBJECTIVE Minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) for lumbar spondylolisthesis allows for surgical treatment of back and leg pain while theoretically minimizing tissue injury and accelerating overall recovery. Although the authors of previous studies have demonstrated shorter length of hospital stay and reduced blood loss with MIS versus open-TLIF, short- and long-term outcomes have been similar. No studies to date have evaluated the comprehensive health care costs associated with TLIF procedures or assessed the cost-utility of MIS- versus open-TLIF. As such, we set out to assess previously unstudied end points of health care cost and cost-utility associated with MIS- versus open-TLIF. METHODS Thirty patients undergoing MIS-TLIF (n=15) or open-TLIF (n=15) for grade I degenerative spondylolisthesis associated back and leg pain were prospectively studied. Total back-related medical resource use, missed work, and health-state values (quality-adjusted life years [QALYs], calculated from EQ-5D with U.S. valuation) were assessed after two-year follow-up. Two-year resource use was multiplied by unit costs on the basis of Medicare national allowable payment amounts (direct cost) and work-day losses were multiplied by the self-reported gross-of-tax wage rate (indirect cost). Difference in mean total cost per QALY gained for MIS- versus open-TLIF was assessed as incremental cost-effectiveness ratio (ICER: COSTmis-COSTopen/QALYmis-QALYopen). RESULTS MIS versus open-TLIF cohorts were similar at baseline. By two years postoperatively, patients undergoing MIS- versus open-TLIF reported similar mean QALYs gained (0.50 vs. 0.41, P=0.17). Mean total two-year cost of MIS- and open-TLIF was

Survival of patients with malignant primary osseous spinal neoplasms: Results from the Surveillance, Epidemiology, and End Results (SEER) database from 1973 to 2003. Clinical article

35,996 and

Determination of minimum clinically important difference in pain, disability, and quality of life after extension of fusion for adjacent-segment disease: Clinical article

44,727, respectively. The

Correlation of preoperative depression and somatic perception scales with postoperative disability and quality of life after lumbar discectomy: Clinical article

8,731 two-year cost savings of MIS- versus open-TLIF did not reach statistical significance (P=0.18) for this sample size. CONCLUSIONS Although our limited sample size prevented statistical significance, MIS- versus open-TLIF was associated with reduced costs over two years while providing equivalent improvement in QALYs. MIS-TLIF allows patients to leave the hospital sooner, achieve narcotic independence sooner, and return to work sooner than open-TLIF. In our experience, MIS- versus open-TLIF is a cost reducing technology in the surgical treatment of medically refractory low-back and leg pain from grade I lumbar spondylolisthesis.

Immediate biomechanical effects of lumbar posterior dynamic stabilization above a circumferential fusion.

BACKGROUND Minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) for lumbar spondylolisthesis allows for the surgical treatment of back/leg pain while minimizing tissue injury and accelerating the patients recovery. Although previous results have shown shorter hospital stays and decreased intraoperative blood loss for MIS versus open TLIF, short- and long-term outcomes have been similar. Therefore, we performed comparative effectiveness and cost-utility analysis for MIS versus open TLIF. METHODS A total of 100 patients (50 MIS, 50 open) undergoing TLIF for lumbar spondylolisthesis were prospectively studied. Back-related medical resource use, missed work, and quality-adjusted life years were assessed. Cost of in-patient care, direct cost (2-year resource use × unit costs based on Medicare national allowable payment amounts), and indirect cost (work-day losses × self-reported gross-of-tax wage rate) were recorded, and the incremental cost-effectiveness ratio was calculated. RESULTS Length of hospitalization and time to return to work were less for MIS versus open TLIF (P = 0.006 and P = 0.03, respectively). MIS versus open TLIF demonstrated similar improvement in patient-reported outcomes assessed. MIS versus open TLIF was associated with a reduction in mean hospital cost of