title: Diagnostic accuracy of urinary reagent strip to determine cerebrospinal fluid chemistry and cellularity.
abstract: BACKGROUND
  The gold standard for diagnosis of meningitis depends on cerebrospinal fluid (CSF) examination by microscopy, biochemistry, and culture, which require an experienced microscopist and laboratory support. We conducted this study to determine if urinary reagent strip is useful to make a semi-quantitative assessment of protein, glucose, and presence of leukocyte esterase in CSF.
  
  
  METHODS
  All consecutive CSF samples were evaluated in a blinded fashion. CSF was tested using Combur-10 urinary reagent strip as an index test, and CSF microscopy and biochemistry as reference standards. Combur-10 (Boehringer Mannheim) is a urinary reagent strip used to estimate ten parameters including protein, glucose, and leukocytes. We estimated diagnostic accuracy of each index test using corresponding cut-off levels (glucose 1 + vs. CSF glucose >50 mg/dL; protein 1 + and 2 + vs. CSF protein >30 mg/dL and >100 mg/dL; leukocyte esterase positivity vs. >10 granulocytes in CSF sample). We constructed receiver operating curves (ROC) to evaluate overall performance of index tests and estimated area under the curve (AUC).
  
  
  RESULTS
  CSF samples of 75 patients were included in the study. All the three indicator tests (CSF cells, protein, and glucose) were normal in 17 (22.6%) samples. Of the three tests, diagnostic accuracy of protein estimation (1 + or more on reagent strip) was best for detection of CSF proteins greater than 30 mg/dL [sensitivity 98.1% (95% CI 90.1-100%); specificity 57.1% (95% CI 34-78.2%)], with AUC of 0.97. Sensitivity and specificity for 2 + on reagent strip and CSF protein > 100 mg/dL were 92.6% (95% CI 75.1-99.1) and 87.5% (95% CI 74.8-95.3), respectively, with AUC of 0.96 (95% CI 0.92-1.01). Leukocyte esterase positivity by test strip had a sensitivity of 85.2 (95% CI 66.3-95.8%) and specificity of 89.6 (95% CI 77.3-96.5%) for detection of CSF granulocytes of more than 10/mm(3).
  
  
  CONCLUSIONS
  Existing urinary reagent strips can be used to diagnose meningitis in low-resource settings.
authors.affiliation: Department of Pathology, Sikkim Manipal Institute of Medical Sciences, Gangtok, Sikkim, India.
authors.forename: Deepti
authors.initials: D
authors.lastname: Joshi
authors.forename: Keerthi
authors.initials: K
authors.lastname: Kundana
authors.forename: Apurva
authors.initials: A
authors.lastname: Puranik
authors.forename: Rajnish
authors.initials: R
authors.lastname: Joshi
keywords: Cerebrospinal fluid; meningitis; urinary reagent strip
references.citation: Trans R Soc Trop Med Hyg. 1999 Jul-Aug;93(4):409-10
references.pmid: 10674090
references.citation: Lancet. 1997 Jan 25;349(9047):287-8
references.pmid: 9014941
references.citation: Med Klin (Munich). 1996 Dec 15;91(12):766-8
references.pmid: 9082161
references.citation: S Afr Med J. 1966 Oct 8;40(36):882-4
references.pmid: 5920425
references.citation: Trop Doct. 2004 Oct;34(4):231-2
references.pmid: 15510953
references.citation: Indian J Med Sci. 2004 Feb;58(2):62-6
references.pmid: 14993718
references.citation: Trop Doct. 2003 Jan;33(1):31-2
references.pmid: 12568518
references.citation: An Esp Pediatr. 1988 Aug;29(2):105-8
references.pmid: 3190014
references.citation: J Pediatr (Rio J). 2001 May-Jun;77(3):203-8
references.pmid: 14647585
references.citation: Eur J Pediatr. 1987 Sep;146(5):515-8
references.pmid: 3315686
references.citation: Lancet. 1995 May 20;345(8960):1290-1
references.pmid: 7746063