Predictors of Citations in Neurosurgical Research.

OBJECTIVE: The number of citations an article receives is an important measure of impact for published research. There are limited published data on predictors of citations in neurosurgery research. We aimed to analyze predictors of citations for neurosurgical articles. METHODS: All articles published in 14 neurosurgical journals in the year 2015 were examined and data collected about their features. The number of citations for each article was tallied using both Web of Science (WoS) and Google Scholar (GS) 2.5 years after their publication in print. Negative binomial regression was then performed to determine the relationship between article features and citation counts for scientific articles. RESULTS: A total of 3923 articles were analyzed, comprising 2867 scientific articles (72.6%) and 1056 nonscientific (editorial, commentary, etc.) articles (27.4%). At 2.5 years, scientific articles had a median [interquartile range] number of citations per article of 3.0 [6.0] and 7.0 [9.0] found in WoS and GS, respectively; nonscientific articles had accumulated median 0.0 [2.0] in both WOS and GS. Articles with the study topic "Spine" had the highest citation count at 4.0 [5.0] and 8.0 [10.0] in WoS and GS, respectively. Significant predictors of citation count in scientific articles were level of evidence, number of centers, number of authors, and impact factor. CONCLUSIONS: This is the largest investigation analyzing predictors of citations in the neurosurgical literature. Factors found to be most influential on citation rates in scientific articles included the study's level of evidence, number of participating centers, number of authors, and the publishing journal's impact factor.

Utility of cerebrospinal fluid lactate in aneurysmal subarachnoid hemorrhage.

BACKGROUND: An external ventricular drain (EVD) treats hydrocephalus in patients with aneurysmal subarachnoid hemorrhage (aSAH). This study examines the utility of cerebrospinal fluid (CSF) lactate collected from an EVD as a proposed biomarker to predict patient outcome and vasospasm/delayed cerebral ischemia. METHODS: Consecutive adults admitted to Wake Forest Baptist Medical Center from 2010 to 2015 with aSAH were identified through the electronic medical record, and clinical variables were collected and analyzed for correlation with incidence of vasospasm and discharge outcome. RESULTS: In all, 51 patients with aSAH and an EVD had CSF lactate measured which ranged from 1.9 to 6.2 mmol/L, with a median value of 3.2 mmol/L. Vasospasm based on transcranial Doppler assessment occurred in 29 patients (57%), of which 20 (45%) were clinically symptomatic. Good outcome (discharge to home/acute rehab) occurred in 35 patients (69%). Sixteen patients (31%) had an unfavorable outcome (died/discharged to nursing homes/long-term acute care facility). In multivariate regression analysis, unfavorable outcome at discharge (P = 0.02), elevated CSF protein (P = 0.04), and admission Hunt and Hess score 3-5 (P = 0.05) were significantly associated with higher CSF lactate. The risk of symptomatic vasospasm increased with lactate in univariate analysis, but did not reach statistical significance (P = 0.077). CONCLUSION: The measurement of the CSF biochemical markers using an EVD is feasible and safe. We found that elevated CSF lactate correlates with patient outcome. Larger prospective studies are needed to test the validity of this finding and for understanding the underlying pathophysiologic mechanisms.

A Pilot Study of the Level of Evidence and Collaboration in Published Neurosurgical Research.

OBJECTIVE: Large-scale studies analyzing neurosurgical published research are lacking. This pilot study was designed to assess feasibility of an ongoing annual neurosurgical literature and research analysis of published articles in English-language neurosurgery journals. METHODS: All scientific articles published during 2015 in the print version of 14 English-language neurosurgery journals were reviewed individually. RESULTS: During 2015, 4065 articles were published in 14 neurosurgical journals. Of these, 1116 (27.5%) were nonscientific articles and were excluded from the analysis, and 2949 scientific articles were analyzed. Of these, 2% and 8.5% of publications met criteria for levels of evidence 1 and 2, respectively. One third of published manuscripts (33.2%) were retrospective chart reviews. There were 1742 different centers (mean 1.95 centers per article; range, 1-19) represented in 2949 articles from 67 countries (mean 1.23 countries per article; range, 1-12). Multicenter collaboration was present in 47.5% of published articles, and international collaboration was present in 17.5%. The highest numbers of U.S. author international collaborations were with Canada (70 collaborations), China (33 collaborations) and Italy (25 collaborations). Data for levels of evidence, multicenter collaborations, and international collaborations are presented for each individual journal and subject within neurosurgery. CONCLUSIONS: This pilot analysis provides a descriptive assessment of levels of evidence and collaboration based on journal, general subject matter, and subcategories of subject allowing for comparison. This methodology may be used on an annual basis to establish neurosurgery publication trends and to identify underrepresented areas of research within the specialty.