Validation of a case definition for leptospirosis diagnosis in patients with acute severe febrile disease admitted in reference hospitals at the State of Pernambuco, Brazil.
BACKGROUND
Leptospirosis is often mistaken for other acute febrile illnesses because of its nonspecific presentation. Bacteriologic, serologic, and molecular methods have several limitations for early diagnosis: technical complexity, low availability, low sensitivity in early disease, or high cost. This study aimed to validate a case definition, based on simple clinical and laboratory tests, that is intended for bedside diagnosis of leptospirosis among hospitalized patients.


METHODS
Adult patients, admitted to two reference hospitals in Recife, Brazil, with a febrile illness of less than 21 days and with a clinical suspicion of leptospirosis, were included to test a case definition comprising ten clinical and laboratory criteria. Leptospirosis was confirmed or excluded by a composite reference standard (microscopic agglutination test, ELISA, and blood culture). Test properties were determined for each cutoff number of the criteria from the case definition.


RESULTS
Ninety seven patients were included; 75 had confirmed leptospirosis and 22 did not. Mean number of criteria from the case definition that were fulfilled was 7.8±1.2 for confirmed leptospirosis and 5.9±1.5 for non-leptospirosis patients (p<0.0001). Best sensitivity (85.3%) and specificity (68.2%) combination was found with a cutoff of 7 or more criteria, reaching positive and negative predictive values of 90.1% and 57.7%, respectively; accuracy was 81.4%.


CONCLUSIONS
The case definition, for a cutoff of at least 7 criteria, reached average sensitivity and specificity, but with a high positive predictive value. Its simplicity and low cost make it useful for rapid bedside leptospirosis diagnosis in Brazilian hospitalized patients with acute severe febrile disease.
Enfermaria de Clínica Médica, Hospital Barão de Lucena, Recife, PE, Brasil. alfredoleite72@gmail.com
Alfredo Pereira Leite de
AP
Albuquerque Filho
Jéssica Guido de
JG
Araújo
Inacelli Queiroz de
IQ
Souza
Luciana Cardoso
LC
Martins
Marta Iglis de
MI
Oliveira
Maria Jesuíta Bezerra da
MJ
Silva
Ulisses Ramos
UR
Montarroyos
Demócrito de Barros
Dde B
Miranda Filho
D000208:Acute Disease; D000328:Adult; D000372:Agglutination Tests; D003428:Cross Infection / Q000175:diagnosis* / Q000382:microbiology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005334:Fever / Q000209:etiology*; D006801:Humans; D007922:Leptospirosis / Q000150:complications / Q000175:diagnosis*; D008297:Male; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity