Neutrophil to lymphocyte count ratio as an early indicator of blood stream infection in the emergency department. Issue 7 (2nd September 2014)

• Record Type: Journal Article
• Authors: Lowsby, Richard; Gomes, Clint; Jarman, Ian; Lisboa, Paulo; Nee, Patrick A; Vardhan, Madhur; Eckersley, Tom; Saleh, Roshan; Mills, Hannah
• Other Names: Al-Jubouri Mohammed author non-byline.; Ames Darren author non-byline.; Anders Jeanette author non-byline.; Ashton Andy author non-byline.; Bolton Nick author non-byline.; Bonney Samantha author non-byline.; Bromiley Martin author non-byline.; Burrows Stacy author non-byline.; Chatha Hridesh author non-byline.; Denmade Craig author non-byline.; Dowling Susan author non-byline.; Eckersley Tom author non-byline.; Gharib Maged author non-byline.; Gomes Clint author non-byline.; Hodgson David author non-byline.; Jarman Ian author non-byline.; Jones Christina author non-byline.; Karim Junaid author non-byline.; Keough Jamie author non-byline.; Khoo Leo author non-byline.; Kontny Gina author non-byline.; Lisboa Paulo author non-byline.; Lowsby Richard author non-byline.; Lyons Marc author non-byline.; Machin Peggy author non-byline.; Mahendran Vijay author non-byline.; McCairn Amanda author non-byline.; McCreary David author non-byline.; McGregor Alasdair author non-byline.; Mills Hannah author non-byline.; Mittal Raj author non-byline.; Nee Patrick author non-byline.; Qureshi Ambreen author non-byline.; Saleh Roshan author non-byline.; Sampson Paul author non-byline.; Sayle Janet author non-byline.; Scott Paula author non-byline.; Sykes Robert author non-byline.; Vardhan Madhur author non-byline.; Todd Victoria author non-byline.; Vallaru Balakrishnan author non-byline.; Wong Jun Jack author non-byline.; Woods Mark author non-byline.;
• Is Part Of: Emergency medicine journal. Volume 32:Issue 7(2015)
• Page Start: 531
• Page End: 534
• Publication Date: 2014-09-02
• Subjects: clinical care -- emergency department -- haematology -- infection; Emergency medicine -- Periodicals; 616.02505
• DOI: 10.1136/emermed-2014-204071
• Languages: English
• ISSNs: 1472-0205

Abstract

Abstract : Objectives: Early identification of patients with blood stream infection (BSI), especially bacteraemia, is important as prompt treatment improves outcome. The initial stages of severe infection may be characterised by increased numbers of neutrophils in the peripheral blood and depression of the lymphocyte count (LC). The neutrophil to LC ratio (NLCR) has previously been compared with conventional tests, such as C-reactive protein (CRP) and white cell count (WCC), and has been proposed as a useful marker in the timely diagnosis of bacteraemia. Methods: Data on consecutive adult patients presenting to the emergency department with pyrexial illness during the study period, November 2009 to October 2010, were analysed. The main outcome measure was positive blood cultures (bacteraemia). Sensitivity, specificity, positive and negative predictive values and likelihood ratios were determined for NLCR, CRP, WCC, neutrophil count and LC. Results: 1954 patients met the inclusion criteria. Blood cultures were positive in 270 patients, hence the prevalence of bacteraemia was 13.8%. With the exception of WCC, there were significant differences in the mean value for each marker between bacteraemic and non-bacteraemic patients (p<0.001). The area under the receiver operating characteristic curve was highest for NLCR (0.72; 95% CI 0.69 to 0.75) and LC (0.71; 0.68 to 0.74) and lowest for WCC (0.54; 0.40 to 0.57). The sensitivity and specificity of NLCR for predicting bacteraemia were 70% (64% to 75%) and 57% (55% to 60%), respectively. Positive and negative predictive values for NLCR were 0.20 (0.18 to 0.23) and 0.92 (0.91 to 0.94), respectively. The positive likelihood ratio was 1.63 (1.48 to 1.79) and the negative likelihood ratio was 0.53 (0.44 to 0.64). Conclusions: Although NLCR outperforms conventional markers of infection, it is insufficient in itself to guide clinical management of patients with suspected BSI, and it offers no advantage over LC. However, it may offer some diagnostic utility when taken into account as part of the overall assessment.