Dustin H. Massel

Malnutrition Predicts Infectious and Wound Complications Following Posterior Lumbar Spinal Fusion

Study Design. A retrospective review of data collected prospectively by the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP). Objective. The aim of this study was to investigate the association between preoperative hypoalbuminemia, a marker for malnutrition, and complications during the 30 days following posterior lumbar fusion surgery. Summary of Background Data. Malnutrition is a potentially modifiable risk factor that may contribute to complications following spinal surgery. Although prior studies have identified associations between malnutrition, delayed wound healing, and surgical site infection (SSI), the evidence for such a relationship within spine surgery is mixed. Methods. Patients who underwent posterior lumbar spinal fusion of one to three levels as part of the ACS-NSQIP were identified. Patients without preoperative serum albumin concentration were excluded. Outcomes were compared between patients with and without hypoalbuminemia (defined as serum albumin concentration <3.5 g/dL). All comparisons were adjusted for baseline differences between populations. Results. Four thousand three hundred ten patients were included. The prevalence of hypoalbuminemia was 4.8%. In comparison to patients with normal albumin concentration, patients with hypoalbuminemia had a higher risk for occurrence of wound dehiscence [1.5% vs. 0.2%, adjusted relative risk (RR) = 5.8, P = 0.006], SSI (5.4% vs. 1.7%, adjusted RR = 2.3, P = 0.010), and urinary tract infection (5.4% vs. 1.5%, adjusted RR = 2.5, P = 0.005). Similarly, patients with hypoalbuminemia had a higher risk for unplanned hospital readmission within 30 days of surgery (11.7% vs. 5.4%, RR = 1.8, P < 0.001). Finally, patients with hypoalbuminemia had a longer mean inpatient stay (5.2 vs. 3.7 days, RR = 1.2, P < 0.001). Conclusion. The present study suggests that malnutrition is an independent risk factor for infectious and wound complications following posterior lumbar fusion. Malnutrition was also associated with an increased length of stay and readmission. Future studies should evaluate methods of correcting malnutrition before lumbar spinal surgery. Such efforts have the potential to meaningfully decrease the rates of adverse events following this procedure. Level of Evidence: 3

Minimally invasive lumbar decompression—the surgical learning curve

BACKGROUND CONTEXT Minimally invasive spine surgery (MIS) procedures carry an inherently difficult learning curve based upon anecdotal evidence. Few studies have investigated the surgeons learning curve for MIS lumbar laminectomy or laminotomy with or without discectomy. PURPOSE To characterize the learning curve of a 1- or 2-level MIS lumbar decompression (LD) based on perioperative and postoperative parameters . STUDY DESIGN/SETTING Retrospective analysis of a prospectively maintained registry was used for this study. PATIENT SAMPLE There were 228 consecutive patients who underwent a primary 1- or 2-level MIS LD by a single surgeon for degenerative spinal pathology from 2009 to 2014. From 2005 to 2006, 50 patients underwent 1- or 2-level open LD consecutively. OUTCOME MEASURES Perioperative and postoperative outcomes (complications, visual analogue scale [VAS] scores, reoperations) were the outcome measures for this study. METHODS Patients were stratified into first and second groups as determined by the case number at which the procedural time reached a plateau. Demographics, comorbidity, pain scores, and surgical outcomes were compared between the first 50 patients and the subsequent 178 patients. The secondary analysis compared the surgical outcomes between the initial 50 MIS and 50 open LD patients. No funds were received in support of this work. RESULTS The initial cohort was older with a higher comorbidity burden (p<.05). However, body mass index, gender, smoking status, and ethnicity did not differ between cohorts. The initial cohort incurred a greater procedural time (p<.001) and longer length of hospitalization (p<.05) than the second cohort. Estimated blood loss (EBL), pain scores, complication rates, recurrent herniation rates, and reoperation rates were similar between groups. In the secondary analysis, the open LD patients demonstrated greater procedural time, higher EBL, and longer length of hospital stay than the MIS patients. However, the reoperation rate and 30-day readmission rate were not different between the MIS and open patients. CONCLUSIONS Continued surgical experience was associated with a reduced operative time, shorter length of hospitalization, and similar blood loss following an MIS LD. Independent of surgical experience, all patients demonstrated similar improvements in clinical outcomes. These findings appear to suggest that although surgical experience may improve perioperative parameters (operative time, length of hospitalization), an MIS LD may initially be performed safely without prior experience.

Incidence and Risk Factors for Pneumonia After Posterior Lumbar Fusion Procedures: An ACS-NSQIP Study.

Study Design. Retrospective study of data collected prospectively by the American College of Surgeons National Surgical Quality Improvement Program. Objective. To determine the incidence and risk factors for development of pneumonia after posterior lumbar fusion (PLF). Summary of Background Data. Postoperative pneumonia has important clinical consequences for patients and the health care system. Few studies have examined pneumonia after spinal fusion procedures. Methods. Patients in the American College of Surgeons National Surgical Quality Improvement Program database who underwent PLF during 2005 to 2013 were included. The primary outcome was a diagnosis of pneumonia within the first 30 postoperative days. Independent risk factors for the development of postoperative pneumonia were identified using multivariate regression. Rates of sepsis and mortality were compared between patients who did and did not develop pneumonia using multivariate regression that adjusted for all demographic, comorbidity, and procedural characteristics. Results. A total of 12,428 patients undergoing PLF were identified. The incidence of pneumonia was 0.59%. Independent risk factors for the development of pneumonia were chronic obstructive pulmonary disease (relative risk [RR] = 2.7, P = 0.006), steroid use (RR = 2.6, P = 0.017), non-insulin–dependent diabetes mellitus (DM) (RR = 2.4, P = 0.003), insulin-dependent DM (RR = 2.9, P = 0.005), and greater number of operative levels (two level: RR = 1.7, P = 0.033; three level: RR = 2.7, P = 0.007). Patients who developed pneumonia had a higher rate of sepsis (15.1% vs. 0.8%, adjusted RR = 14.5, P < 0.001) and mortality (2.7% versus 0.1%, adjusted RR = 27.0, P < 0.001) than other patients. Of all sepsis cases and postoperative mortalities, 10.5% and 18.2% occurred in patients who had developed pneumonia, respectively. Conclusion. Pneumonia occurs in approximately 1 in 200 patients after PLF. Pneumonia plays a significant role in the development of sepsis and mortality, with 10% of sepsis and 20% of mortality cases occurring in patients who had developed pneumonia. Patients with chronic obstructive pulmonary disease, steroid use, DM, and a greater number of operative levels are at greater risk. These patients should be counseled, monitored, and targeted with preventative interventions accordingly. Level of Evidence: 3

Anterior Cervical Discectomy and Fusion: The Surgical Learning Curve

Study Design. Case-series Objective. The aim of the study was to investigate changes in intraoperative and postoperative parameters associated with the surgical learning curve for anterior cervical discectomy and fusion (ACDF). Summary of Background Data. ACDF is a common surgical spine procedure. The surgical learning curve for this procedure has not been previously characterized. Methods. A prospectively maintained surgical database of consecutive patients who underwent primary 1–2 level ACDF for degenerative spine disease from 2006 to 2014 was reviewed. Patients with concurrent or revision procedures were excluded. The series began after the surgeons fellowship and includes his first case as an attending. A total of 374 patients were divided sequentially into cohorts of 125 (early), 125 (middle), and 124 (late). Statistical analyses utilized independent sample t tests, chi squared tests, and multivariate regression adjusted for preoperative characteristics. The learning curve of operative time was characterized using three-parameter asymptotic regression and two separate linear regressions. Results. The earliest cohort had a greater comorbidity burden, percentage of smokers, and Medicare patients, with fewer workers’ compensation patients when compared to later cohorts. Later cohorts demonstrated decreased mean operative time and estimated blood loss (EBL) and increased arthrodesis rate. Asymptotic and linear regression analyses demonstrated that 50% of the learning curve occurred at case 17 and 31, respectively, whereas 90% of potential improvement occurred by case 56 and 57, respectively. Conclusion. A significant learning curve exists for surgeons performing ACDFs. Patients undergoing ACDF will experience shorter operations, less EBL, and greater arthrodesis rates as the surgeon gains experience. Operative proficiency can be expected to occur by case 60, with arthrodesis rate increasing over a longer period. These results suggest that despite longer operative times and increased EBL with earlier cases, ACDF can safely and effectively be performed at the onset of a surgeons career. This conclusion may be useful to new surgeons debating between operative and nonoperative management of cervical degenerative disc disease. Level of Evidence: 4

Differences in Short-term Outcomes Between Primary and Revision Anterior Cervical Discectomy and Fusion.

STUDY DESIGN Retrospective cohort study. OBJECTIVE To compare short-term morbidity for primary and revision anterior cervical discectomy and fusion (ACDF). SUMMARY OF BACKGROUND DATA Revision ACDF procedures are relatively common, yet their risks are poorly characterized in the literature. There is a need to assess the relative risk of revision ACDF procedures compared with primary surgery. METHODS The prospectively collected American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was used to identify patients who underwent primary and revision ACDF from 2005 to 2014. The occurrence of 30-day postoperative complications, readmission, operative time, and postoperative length of stay were compared between primary and revision procedures using multivariate regression to control for patient and operative characteristics. RESULTS A total of 20,383 ACDF procedures were identified, 1219 (6.0%) of which were revision cases. On multivariate analysis, revision procedures were associated with significantly increased risk of any adverse event (relative risk [RR] 2.3, P < 0.001), any severe adverse event (RR 2.2, P < 0.001), thromboembolic events (RR 3.3, P = 0.001), surgical site infections (RR 3.2, P < 0.001), return to the operating room (RR 1.9, P = 0.001), any minor adverse event (RR 2.5, P < 0.001), and blood transfusion (RR 8.3, P < 0.001). Revision procedures had significantly increased risk of readmission within 30 days (RR = 1.6, P = 0.001). Minor, but statistically significant increases in average operative time and postoperative length of stay were identified for revisions procedures (7 min and half a day, respectively [P < 0.001 for both]). CONCLUSION Revision procedures were associated with significantly increased risk of multiple adverse outcomes, including thromboembolic events, surgical site infections, return to the operating room, blood transfusion, and readmission within 30 days. These results are important for patient counseling and risk stratification. LEVEL OF EVIDENCE 3.STUDY DESIGN Retrospective cohort study. OBJECTIVE To compare short-term morbidity for primary and revision anterior cervical discectomy and fusion (ACDF). SUMMARY OF BACKGROUND DATA Revision ACDF procedures are relatively common, yet their risks are poorly characterized in the literature. There is a need to assess the relative risk of revision ACDF procedures compared to primary surgery. METHODS The prospectively collected American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was used to identify patients that underwent primary and revision ACDF from 2005 to 2014. The occurrence of 30-day postoperative complications, readmission, operative time, and postoperative length of stay were compared between primary and revision procedures using multivariate regression to control for patient and operative characteristics. RESULTS A total of 20,383 ACDF procedures were identified, 1,219 (6.0%) of which were revision cases. On multivariate analysis, revision procedures were associated with significantly increased risk of any adverse event (RR 2.3, p < 0.001), any severe adverse event (RR 2.2, p < 0.001), thromboembolic events (RR 3.3, p = 0.001), surgical site infections (RR 3.2, p < 0.001), return to the operating room (RR 1.9, p = 0.001), any minor adverse event (RR 2.5, p < 0.001), and blood transfusion (RR 8.3, p < 0.001). Revision procedures had significantly increased risk of readmission within 30 days (RR = 1.6, p = 0.001). Minor, but statistically significant increases in average operative time and postoperative length of stay were identified for revisions procedures (7 minutes and half a day, respectively [p < 0.001 for both]). CONCLUSIONS Revision procedures were associated with significantly increased risk of multiple adverse outcomes, including thromboembolic events, surgical site infections, return to the operating room, blood transfusion, and readmission within 30 days. These results are important for patient counseling and risk-stratification. LEVEL OF EVIDENCE 3.

Effect of Surgeon Volume on Complications, Length of Stay, and Costs Following Anterior Cervical Fusion

Study Design. Retrospective cohort. Objective. To identify the association between surgeon volume and inpatient complications, length of stay, and costs associated with ACF. Summary of Background Data. Increased surgeon volume may be associated with improved outcomes after surgical procedures. However, there is a lack of information on the effect of surgeon volume on short-term outcomes after anterior cervical fusion (ACF). Methods. A retrospective cohort study of ACF patients was performed using the Nationwide Inpatient Sample (NIS) from 2003 to 2009. Surgeon volume was divided into three categories, volume <25th percentile, 25th to 74th percentile, and ≥75th percentile of surgeon volume. Multivariate regression was used to compare the rates of adverse events, hospital length of stay, and total hospital costs between surgeon volume categories. Results. A total of 419,212 ACF patients were identified. The 25th percentile for volume was 5 cases per year, and the 75th percentile for volume was 67 cases per year. Volume <25th percentile was associated with increased rates of any adverse event (odd ratio, OR 3.8, P < 0.001), and multiple individual complications including death (OR 2.5, P=0.014), myocardial infarction (OR4.4, P < 0.001), sepsis (OR 4.1, P < 0.001), and surgical site infection (OR 4.0, P < 0.001). Notably, volume ≥75th percentile was associated with decreased rates of any adverse event (OR 0.7, P < 0.001) and death (OR 0.6, P = 0.028). On multivariate analysis, length of stay was significantly increased by 2.3 days (P < 0.001) for surgeons <25th percentile of volume and was decreased by 0.3 days for surgeons with volume ≥75th percentile. Hospital costs were

Multimodal Versus Patient-Controlled Analgesia After an Anterior Cervical Decompression and Fusion.

4569 more for surgeons with <25th percentile of volume and

Multimodal Analgesia versus Intravenous Patient-controlled Analgesia For Minimally Invasive Transforaminal Lumbar Interbody Fusion Procedures.

1213 less for surgeons with ≥75th percentile volume. Conclusion. In this nationally representative sample, surgeons with volume <25th percentile had significantly increased complications, length of stay, and costs. Conversely, surgeons with ≥75th percentile volume experienced decreased complications, length of stay, and costs. Level of Evidence: 4

Comparison of Surgical Outcomes, Narcotics Utilization, and Costs After an Anterior Cervical Discectomy and Fusion: Stand-alone Cage Versus Anterior Plating.

Study Design. Retrospective analysis of a prospectively maintained surgical registry. Objective. To compare postoperative narcotic consumption between multimodal analgesia (MMA) and patient-controlled analgesia (PCA) after an anterior cervical discectomy and fusion (ACDF). Summary of Background Data. Studies suggest that a multimodal approach to pain management leads to decreased pain and morphine consumption after total joint arthroplasty and lumbar spinal procedures. Patients and surgeons would benefit from knowing whether a multimodal approach to pain management is superior to PCA for ACDF. Methods. A retrospective cohort study of ACDF patients receiving either MMA or PCA was conducted. Inpatient narcotic consumption, pain scores, nausea/vomiting, hospital length of stay, and narcotic dependence during the months after surgery were compared between MMA and PCA. Results. A total of 239 patients met inclusion criteria. Of these, 55 (23.0%) received MMA and 184 (77.0%) received PCA. Patients who received MMA had a lower rate of inpatient narcotic consumption (2.5 OME/h vs. 5.8 OME/h, P < 0.001) were less likely to experience nausea/vomiting during the hospitalization (5.5% vs. 37.5%, P < 0.001), and had a shorter hospital length of stay (27.3 vs. 40.1 h, P < 0.001). However, there was no difference between groups in mean visual analogue pain scale during postoperative day zero (4.7 for MMA vs. 5.2 for PCA, P = 0.126) or during postoperative day one (4.1 for MMA vs. 4.1 for PCA, P = 0.937). In addition, there was no difference in the rate of narcotic dependence at the first (P = 0.626) or second (P = 0.480) postoperative visits. Conclusion. These data suggest that MMA results in lower narcotic consumption than PCA after an ACDF. This difference is associated with a shorter inpatient stay and a decrease in postoperative nausea/vomiting. Critically, MMA and PCA appear to provide similar postoperative analgesia. Level of Evidence: 3

Preoperative mental health status may not be predictive of improvements in patient-reported outcomes following an anterior cervical discectomy and fusion

Study Design. Retrospective analysis. Objective. To compare postoperative narcotic consumption and pain scores between multimodal analgesia (MMA) and patient-controlled analgesia (PCA) following minimally invasive transforaminal lumbar interbody fusion (MIS TLIF). Summary of Background Data. A multimodal analgesic approach to pain management may lead to decreased pain and narcotic consumption after orthopedic procedures. Additional evidence is, however, required to determine how MMA compares to intravenous PCA after MIS TLIF. Methods. Patients undergoing 1-level MIS TLIF followed by either MMA or PCA at our institution were compared in terms of inpatient pain scores, narcotic consumption, hospital length of stay, rates of surgical complications, rates of inpatient nausea/vomiting, rates of postoperative urinary retention, and rates of narcotic consumption during the months after discharge. Results. A total of 139 patients met inclusion criteria. Of these, 39 (28.1%) received MMA and 100 (71.9%) received PCA. Demographic and comorbidity characteristics did not differ between cohorts. Compared with patients receiving PCA, patients receiving MMA had a lower rate of inpatient narcotic consumption (2.8 ± 1.9 vs. 5.3 ± 4.4 oral morphine equivalents/hour, P < 0.001), a lower rate of inpatient nausea/vomiting (20.5% vs. 48.0%; P = 0.003), and a shorter hospital length of stay (53.0 ± 25.3 vs. 62.6 ± 24.4 h, P = 0.041). There were no differences in Numeric Rating Scale pain score between cohorts for day 0, postoperative day 1, or postoperative day 2 (P > 0.05 for each). There was no difference in the rate of postoperative urinary retention (P > 0.05). Similarly, there were no differences in narcotic consumption at 6 or 12 weeks postoperatively (P > 0.05 for each). Conclusion. These findings suggest that MMA results in reduced inpatient hospital narcotic consumption compared with PCA after MIS TLIF. The decrease in narcotic consumption may contribute to the observed decrease in the rate of inpatient nausea/vomiting and shorter hospital length of stay. Importantly, MMA and PCA resulted in similar analgesia for patients during the inpatient stay. Level of Evidence: 4