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Sensitivity (Se), speci- ficity (Sp) and the best cut- off value (based on Youden index)

were measured. P-val- ue of <0.05: statistically signif- icant. Data analysis was per-
formed with the IBM SPSS Statistics 19.

Results: Females: 3 (23%), males: 10 (77%).Six patients survived (46.15%) and 7 died

(53.85%).Mean age, length of ICU stay, GCS, APACHE-II, R-Origi- nal and R-Modified:
51.62 ± 7.638, 12±5.191, 9 ± 0.76, 12.85 ± 1.367, 0.121924 ± 0.0261, and 0.182154 ±

0.1207 respectively. Mean value of R_Original: 0.083114 ± 0.0204 (survivors) and
0.155190 ± 0.4276 (deceased). Mean val- ue of R_Modified: 0.129833 ± 0.0297

(survivors) and 0.227000 ± 0.0530 (deceased).Correlation value for the two rates:
0.998 (p=0.000). Paired samples ttest: mean paired difference of -0.0602298 ±

0.0077 (t=-7.847, df=12, 2- tailed p=0.000). Area under the ROC (AUC) for R_Original:
0.810 ± 0.138 (p=0.063), while for R_Modified: 0.798 ± 0.140 (p=0.074) (Image 1).

Based on Youden index (0.548) R_Original and R_Modified showed a cut-off value of
0.112952 and 0.1755 respec- tively with the same Se (71.4%) and Sp (83.3%). The
Hosmer-Lemeshow test gave a χ2 value of 8.72 (df=8, p=0.366) and 9.03 (df=8,

p=0.340) for R_Original and R_Modified re- spectively.

Conclusions: Both R_Original and R_Modified presented good discrimination and

calibration with a high degree of corre- lation. R_Modified computed a bigger death
rate in both alive and dead patients with moderate HI. This finding is in line with other

studies show- ing that the initial APACHE- II equation (incorporating diag- nostic
category weight) underestimates R in patients with HI. Our findings suggest that a

R_Modified value of 0.227 is the best cut-off value in this specific group.

7. Spine journals through citation metrics: is there a difference?

Georgios Matis, Theodossios Birbilis, Olga Chrysou, Kosmas Kontogiannidis, Elena

Karakosta, Athanassios Zissimopoulos, Michail Karanikas, Nikolaos Lyratzopoulos,
Georgios Minopoulos.

Ανακοινώθηκε στο 14 European Congress of Neurosurgery (EANS), Rome, Italy,
th
0914/10/2011).

Δημοσιεύτηκε σαν E-Poster 276

Abstract

Introduction: Journals can be ranked by frequency and impact of citations.

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