Shock Index As A Predictor Of Hyperlactatemia For Early Detection Of Severe Sepsis In Patients Presenting To The Emergency Department Of A Low To Middle Income Country.

BACKGROUND

Early detection of sepsis in the emergency department is of prime importance and requires tools that are time and cost-effective. The Systemic Inflammatory Response Syndrome (SIRS) has been poorly associated with sepsis. Timothy et al in a retrospective analysis of Emergency Department (ED) visit stated estimate of SIRS at 17.8% accounting to an annual yield of 16.6 million adult visits with SIRS per year, among these only 26% accounted as an infectious aetiology of SIRS, trauma being 10% and other causes being rare. Shock index is found to be independently associated with 30-day mortality in a broad population of ED patients including sepsis. With limited health resources in a low to middle income country, focused utilization is important and so is the need for markers that are non-invasive, readily available, cost effective, and easy to interpret. Shock index can serve this purpose as a surrogate marker of disease severity in patients with severe sepsis and thus resulting in early detection of such patients.

METHODS

This cross-sectional study was conducted from December 2014 to May 2015 at a tertiary care setup (Aga Khan University Hospital) in Karachi consisting of all septic patients received at the emergency department. Non-probability sampling technique was used. p-value <0.05 was taken as significant.

RESULTS

Out of 180 study participants 94 (52.22%) were males while 86 (47.78%) were females. The mean age was 57.48±18.8 years. Cohen's κ was used to determine an agreement between the Shock index and Lactate levels. Shock index with cut off value of > 0.7 was used and moderate to the strong agreement between the two was found with kappa κ = 0.786 which was statistically significant (p=<0.001). Sensitivity was found to be 0.99, specificity 0.75, NPV 0.98, PPV 0.87.

CONCLUSIONS

To conclude the shock index has some very favourable features, including availability, low cost, and direct relevance to sepsis in terms of its high validity. A high SI predicts elevated lactate levels in patients with sepsis.