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Dive into the research topics where Nicholas B. Abt is active.

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Featured researches published by Nicholas B. Abt.


Spine | 2015

The impact of obesity on short- and long-term outcomes after lumbar fusion

Rafael De la Garza-Ramos; Mohamad Bydon; Nicholas B. Abt; Daniel M. Sciubba; Jean Paul Wolinsky; Ali Bydon; Ziya L. Gokaslan; Bruce Rabin; Timothy F. Witham

Study Design. Retrospective cohort study. Objective. To compare short- and long-term outcomes in obese versus nonobese patients undergoing instrumented posterolateral fusion of the lumbar spine. Summary of Background Data. Obesity is an important public health issue due to the negative effects on quality of life. Some studies have shown an association between obesity and higher rates of complications and unfavorable outcomes after spine surgery. Methods. We retrospectively reviewed medical records for all adult patients undergoing 1- to 3-level posterolateral fusion for degenerative spine disease between 1992 and 2012 at a single institution. Patients were divided into obese (body mass index > 30 kg/m2) and nonobese cohorts to compare complications, reoperation rates, and symptom resolution at the last follow-up. A regression model was used to estimate relative risk ratios. Results. During the study period, 732 patients underwent lumbar fusion, with 662 (90.44%) nonobese patients and 70 (9.56%) obese patients in the cohort. Obese patients had significantly higher blood loss intraoperatively (P = 0.002) and a longer average length of stay (P = 0.022). Moreover, obesity was independently associated with a significantly increased risk of developing a postoperative complication (risk ratio 2.14; 95% confidence interval, 1.10–4.16) and surgical site infection (risk ratio 3.11; 95% confidence interval, 1.48–6.52). At the last follow-up, a higher proportion of obese patients had radiculopathy (P = 0.018), motor deficits (P = 0.006), sensory deficits (P = 0.008), and bowel or bladder dysfunction (P = 0.006) than nonobese patients. Conclusion. In this study, obese patients undergoing lumbar fusion had higher blood loss, longer lengths of stay, higher complication rates, and worse functional outcomes at the last follow-up than nonobese patients. These findings suggest that both surgeons and patients should acknowledge the significantly increased morbidity profile of obese patients after lumbar fusion. Level of Evidence: 4


Journal of Neurosurgery | 2015

Impact of resident participation on morbidity and mortality in neurosurgical procedures: an analysis of 16,098 patients

Mohamad Bydon; Nicholas B. Abt; Rafael De la Garza-Ramos; Mohamed Macki; Timothy F. Witham; Ziya L. Gokaslan; Ali Bydon; Judy Huang

OBJECT The authors sought to determine the impact of resident participation on overall 30-day morbidity and mortality following neurosurgical procedures. METHODS The American College of Surgeons National Surgical Quality Improvement Program database was queried for all patients who had undergone neurosurgical procedures between 2006 and 2012. The operating surgeon(s), whether an attending only or attending plus resident, was assessed for his or her influence on morbidity and mortality. Multivariate logistic regression, was used to estimate odds ratios for 30-day postoperative morbidity and mortality outcomes for the attending-only compared with the attending plus resident cohorts (attending group and attending+resident group, respectively). RESULTS The study population consisted of 16,098 patients who had undergone elective or emergent neurosurgical procedures. The mean patient age was 56.8 ± 15.0 years, and 49.8% of patients were women. Overall, 15.8% of all patients had at least one postoperative complication. The attending+resident group demonstrated a complication rate of 20.12%, while patients with an attending-only surgeon had a statistically significantly lower complication rate at 11.70% (p < 0.001). In the total population, 263 patients (1.63%) died within 30 days of surgery. Stratified by operating surgeon status, 162 patients (2.07%) in the attending+resident group died versus 101 (1.22%) in the attending group, which was statistically significant (p < 0.001). Regression analyses compared patients who had resident participation to those with only attending surgeons, the referent group. Following adjustment for preoperative patient characteristics and comorbidities, multivariate regression analysis demonstrated that patients with resident participation in their surgery had the same odds of 30-day morbidity (OR = 1.05, 95% CI 0.94-1.17) and mortality (OR = 0.92, 95% CI 0.66-1.28) as their attending only counterparts. CONCLUSIONS Cases with resident participation had higher rates of mortality and morbidity; however, these cases also involved patients with more comorbidities initially. On multivariate analysis, resident participation was not an independent risk factor for postoperative 30-day morbidity or mortality following elective or emergent neurosurgical procedures.


Spine | 2014

Impact of smoking on complication and pseudarthrosis rates after single- and 2-level posterolateral fusion of the lumbar spine.

Mohamad Bydon; Rafael De la Garza-Ramos; Nicholas B. Abt; Ziya L. Gokaslan; Jean Paul Wolinsky; Daniel M. Sciubba; Ali Bydon; Timothy F. Witham

Study Design. Retrospective study. Objective. To study the impact of smoking status on postoperative complications and pseudarthrosis in adult patients undergoing posterolateral fusion (PLF) of the lumbar spine. Summary of Background Data. Results of studies analyzing the impact of smoking on complication and pseudarthrosis rates after spine surgery are conflicting. Methods. A retrospective medical record review was performed to identify all adult patients who underwent single- and 2-level instrumented PLF without interbody devices for degenerative spine disease in a 21-year period at a single institution. Patients were divided into smokers and nonsmokers. The main outcome variables were development of at least one postoperative complication and development of pseudarthrosis. Results. A total of 281 patients underwent single- or 2-level PLF in the 21-year period. Of these, 231 (82.21%) patients were nonsmokers and 50 (17.9%) were smokers. For patients undergoing single-level PLF, complication rates in nonsmokers (3.57%) versus smokers (7.69%) were not significantly different (P = 0.353); pseudarthrosis in nonsmokers occurred in 9.82% of cases compared with 7.69% in the smokers group (P = 0.738). Nonsmokers undergoing 2-level PLF had complication rates of 6.72%, compared with 4.17% in smokers (P = 0.638), but pseudarthrosis rates were significantly higher in the smokers group than in the nonsmokers group (29.17% vs. 10.92%; P = 0.019). Patients were followed up for an average of 53.5 months. Conclusion. The findings in this study suggest that smoking has a significant impact on pseudarthrosis rates after 2-level PLF of the lumbar spine, but not necessarily on single-level PLF. Level of Evidence: 4


The Spine Journal | 2015

The cost-effectiveness of interbody fusions versus posterolateral fusions in 137 patients with lumbar spondylolisthesis.

Mohamad Bydon; Mohamed Macki; Nicholas B. Abt; Timothy F. Witham; Jean Paul Wolinsky; Ziya L. Gokaslan; Ali Bydon; Daniel M. Sciubba

BACKGROUND CONTEXT Reimbursements for interbody fusions have declined recently because of their questionable cost-effectiveness. PURPOSE A Markov model was adopted to compare the cost-effectiveness of posterior lumbar interbody fusion (PLIF) or transforaminal lumbar interbody fusion (/TLIF) versus noninterbody fusion and posterolateral fusion (PLF) in patients with lumbar spondylolisthesis. STUDY DESIGN/SETTING Decision model analysis based on retrospective data from a single institutional series. PATIENT SAMPLE One hundred thirty-seven patients underwent first-time instrumented lumbar fusions for degenerative or isthmic spondylolisthesis. OUTCOME MEASURES Quality of life adjustments and expenditures were assigned to each short-term complication (durotomy, surgical site infection, and medical complication) and long-term outcome (bowel/bladder dysfunction and paraplegia, neurologic deficit, and chronic back pain). METHODS Patients were divided into a PLF cohort and a PLF plus PLIF/TLIF cohort. Anterior techniques and multilevel interbody fusions were excluded. Each short-term complication and long-term outcome was assigned a numerical quality-adjusted life-year (QALY), based on time trade-off values in the Beaver Dam Health Outcomes Study. The cost data for short-term complications were calculated from charges accrued by the institutions finance sector, and the cost data for long-term outcomes were estimated from the literature. The difference in cost of PLF plus PLIF/TLIF from the cost of PLF alone divided by the difference in QALY equals the cost-effectiveness ratio (CER). We do not report any study funding sources or any study-specific appraisal of potential conflict of interest-associated biases in this article. RESULTS Of 137 first-time lumbar fusions for spondylolisthesis, 83 patients underwent PLF and 54 underwent PLIF/TLIF. The average time to reoperation was 3.5 years. The mean QALY over 3.5 years was 2.81 in the PLF cohort versus 2.66 in the PLIFo/TLIF cohort (p=.110). The mean 3.5-year costs of


Surgical Neurology International | 2014

Preoperative anemia increases postoperative morbidity in elective cranial neurosurgery

Mohamad Bydon; Nicholas B. Abt; Mohamed Macki; Henry Brem; Judy Huang; Ali Bydon; Rafael J. Tamargo

54,827.05 after index interbody fusion were statistically higher than that of the


Archives of Otolaryngology-head & Neck Surgery | 2016

Assessment of the Predictive Value of the Modified Frailty Index for Clavien-Dindo Grade IV Critical Care Complications in Major Head and Neck Cancer Operations

Nicholas B. Abt; Jeremy D. Richmon; Wayne M. Koch; David W. Eisele; Nishant Agrawal

48,822.76 after PLF (p=.042). The CER of interbody fusion to PLF after the first operation was -


Neurological Research | 2016

Deep-wound and organ-space infection after surgery for degenerative spine disease: an analysis from 2006 to 2012

Rafael De la Garza-Ramos; Nicholas B. Abt; Panagiotis Kerezoudis; Brandon A. McCutcheon; Ali Bydon; Ziya L. Gokaslan; Mohamad Bydon

46,699.40 per QALY; however, of the 27 patients requiring reoperation, the incident (reoperation) rate ratio was 7.89 times higher after PLF (2.91, 26.67). The CER after the first reoperation was -


Clinical Neurology and Neurosurgery | 2016

Thirty day postoperative outcomes following anterior lumbar interbody fusion using the national surgical quality improvement program database

Nicholas B. Abt; Rafael De la Garza-Ramos; Israel O. Olorundare; Brandon A. McCutcheon; Ali Bydon; Jeremy L. Fogelson; Ahmad Nassr; Mohamad Bydon

24,429.04 per QALY (relative to PLF). Two patients in the PLF cohort required a second reoperation, whereas none required a second reoperation in the PLIF/TLIF cohort. Taken collectively, the total CER for the interbody fusion is


Neurosurgery | 2015

Impact of Age on Short-term Outcomes After Lumbar Fusion: An Analysis of 1395 Patients Stratified by Decade Cohorts.

Mohamad Bydon; Nicholas B. Abt; Rafael De la Garza-Ramos; Israel O. Olorundare; Kelly McGovern; Daniel M. Sciubba; Ziya L. Gokaslan; Ali Bydon

9,883.97 per QALY. CONCLUSIONS The reoperation rate was statistically higher for PLF, whereas the negative CER for the initial operation and first reoperation favors PLF. However, when second reoperations were included, the CER for the interbody fusion became


JAMA Surgery | 2014

Neoadjuvant Chemotherapy and Short-term Morbidity in Patients Undergoing Mastectomy With and Without Breast Reconstruction

Nicholas B. Abt; José M. Flores; Pablo A. Baltodano; Karim A. Sarhane; Francis M. Abreu; Carisa M. Cooney; Michele A. Manahan; Vered Stearns; Martin A. Makary; Gedge D. Rosson

9,883.97 per QALY, suggesting moderate long-term cost savings and better functional outcomes with the interbody fusion.

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Ali Bydon

Johns Hopkins University

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Rafael De la Garza-Ramos

Johns Hopkins University School of Medicine

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Ziya L. Gokaslan

Baylor College of Medicine

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Mohamed Macki

Johns Hopkins University

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Timothy F. Witham

Johns Hopkins University School of Medicine

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Pablo A. Baltodano

Johns Hopkins University School of Medicine

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