Biochemical analysis of cerebrospinal fluid in the laboratories of deployed medical treatment facilities: are Multistix 10 SG strip and iSTAT useful?

INTRODUCTION

During military deployment, the diagnosis and the management of acute bacterial meningitis can be problematic, as deployed Medical Treatment Facilities (MTFs) often have a limited laboratory diagnostic capability. However, French Role 2 and 3 MTFs have point-of-care (POC) testing to perform urinary (Multistix 10 SG strip) and blood (iSTAT handheld analyser) biochemical testing mentioned in AMedP8.5. The purpose of this study was to compare the accuracy of this urine test strip and of the iSTAT CHEM8 and CG4 cartridges with a standard hospital bench top analyser in order to determine if these POC devices have a potential role in the biochemical analysis of cerebrospinal fluid (CSF protein, CSF glucose and CSF lactate, respectively).

METHODS

Agreement between the index methods and the reference methods (suitable kits on the Cobas 6 000 System) was evaluated by parallel testing of 30 CSF samples by both techniques. For CSF protein, agreement between the strip and the reference method was evaluated determining the κ coefficient. For CSF glucose and CSF lactate subgroups, least squares linear regressions were calculated and Bland-Altman analyses were performed.

RESULTS

The Multistix 10 SG strip can be used to make a semiquantitative determination of CSF protein. A good agreement between the strip and the reference method was observed (κ coefficient: 0.93 (IC 0.82 to 1)). This strip is thus well adapted to demonstrate an elevation of CSF protein level as observed in acute bacterial meningitis. The iSTAT CHEM8 and CG4+ cartridges correlated well with the reference methods for the determination of CSF glucose and CSF lactate, respectively (r>0.98) but exhibited a negative bias (∼ -7% and ∼ -15%, respectively).

CONCLUSIONS

The combined use of the Multistix 10 SG strip and of the iSTAT system appears to be an attractive solution for the biochemical investigation of CSF in medical treatment facilities with limited laboratory diagnostic capability.