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Prospective clinical evaluation of lower cut‐offs for galactomannan detection in adult neutropenic cancer patients and haematological stem cell transplant recipients
Author(s) -
Maertens Johan,
Theunissen Koen,
Verbeken Eric,
Lagrou Katrien,
Verhaegen Jan,
Boogaerts Marc,
Eldere Johan Van
Publication year - 2004
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1111/j.1365-2141.2004.05140.x
Subject(s) - galactomannan , aspergillosis , medicine , hematology , neutropenia , cut off , aspergillus , oncology , immunology , surgery , gastroenterology , chemotherapy , biology , power (physics) , physics , botany , quantum mechanics
Summary The recent advent of an improved commercial serum enzyme‐linked immunosorbent assay (ELISA) for the detection of circulating galactomannan (GM), a major constituent of Aspergillus cell walls, has contributed to the diagnosis of invasive aspergillosis (IA) in many haematology and transplant centres. However, the optimal threshold for positivity remains a matter of debate. We prospectively evaluated the impact of lowering the cut‐off in 124 neutropenic episodes with a high pretest probability for IA. Two new cut‐off points, lower than previously accepted, are proposed: (a) a ‘static’ cut‐off at 0·8 and (b) a ‘dynamic’ cut‐off at 0·5. A single assay with an optical density (OD) index ≥0·8 warrants the initiation of anti‐ Aspergillus therapy. A further lowering of the ‘static’ threshold seems not clinically feasible given the drop in positive predictive value (PPV). However, the demonstration of at least two sequential sera with an OD ≥0·5 (‘dynamic’ threshold) increased the specificity and the PPV to 98·6% and the efficiency to 98%. Applying both cut‐offs to a subgroup of 21 ‘possible’ fungal infections further identified and upgraded six cases of IA. However, the clinical benefit of lower cut‐offs (particularly for earlier diagnosis) depends upon the kinetics of antigenaemia and the intensity of serum sampling.