Is there yet any place for reagent strips in diagnosing spontaneous bacterial peritonitis in cirrhotic patients? An accuracy and cost-effectiveness study in Brazil.
BACKGROUND
Diagnosis of spontaneous bacterial peritonitis (SBP) is currently based on ascitic cell counting, but there is a need for a more simple and rapid diagnostic tool. The objectives of this study are to evaluate the accuracy of reagent strips in diagnosing SBP and compare their costs with total and differential cell counts.


METHODS
71 cirrhotic in- and outpatients were consecutively included (159 samples). Spontaneous bacterial peritonitis was defined as neutrophil cells >or= 250/microL. The cutoff values for each reagent strip were defined by a receiver operating characteristic (ROC) curve. Sensitivity (S), Specificity (Sp), Positive and Negative Predictive Values (PPV and NPV), Accuracy (Ac) and cost-effectiveness (US$) in comparison to cell count exam were calculated.


RESULTS
Spontaneous bacterial peritonitis was diagnosed in 17 patients (23.9%), 11 of them with positive culture (64.7%). The best cutoff points found in ROC curves were 1+ for Multistix 10 SG and ca. 75 for Choiceline 10 (Multistix 10 SG S = 80%, Sp = 98.5%, PPV = 90.9%, NPV = 96.2%, Ac = 95%; Choiceline 10 S = 76.9%, Sp = 97.7%, PPV = 87%, NPV = 95.6%, Ac = 94%). In terms of cost-effectiveness by cost/accuracy, cell count was 41.5, Multistix 10 SG 0.57, and Choiceline 10, 0.19 (P < 0.001).


CONCLUSIONS
Reagent strips are a useful tool for diagnosing SBP in cirrhotic patients, but they have some limitations. Strips are especially indicated when total and differential cell counts are not quickly available or sometimes unavailable. They are also indicated as screening test in emergency rooms to anticipate the diagnosis of SBP and allow its early treatment. It's an interesting option in developing countries.
de Araujo
Alexandre
A
Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul Gastroenterology, Porto Alegre, Brazil. araujo-ale@ig.com.br
de Barros Lopes
Antônio
A
Trucollo Michalczuk
Matheus
M
Stifft
Jonathas
J
Nardelli
Enzo
E
Escobar
Gabriela
G
Rossi
Gabriela
G
Alvares-da-Silva
Mário Reis
MR
D000328:Adult; D000368:Aged; D015373:Bacterial Typing Techniques; D001938:Brazil; D002265:Carboxylic Ester Hydrolases / Q000032:analysis*; D004796:Clinical Enzyme Tests / Q000191:economics*; D003362:Cost-Benefit Analysis; D005260:Female; D006801:Humans; D007958:Leukocyte Count / Q000191:economics*; D008103:Liver Cirrhosis / Q000150:complications*; D008297:Male; D008875:Middle Aged; D009504:Neutrophils / Q000201:enzymology*; D019152:Paracentesis; D010538:Peritonitis / Q000097:blood / Q000175:diagnosis* / Q000209:etiology / Q000382:microbiology; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D011933:Reagent Kits, Diagnostic / Q000191:economics*; D011934:Reagent Strips / Q000191:economics*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult
D011933:Reagent Kits, Diagnostic; D011934:Reagent Strips; C021443:leukocyte esterase; D002265:Carboxylic Ester Hydrolases