Objectives:
Aspergillus related diseases burden millions of people in both high and low-income countries. Their diagnosis rely on various criteria, including serology. Numerous tests are available for the detection of IgG directed against Aspergillus, but none comply with the WHO ASSURED (Affordable, Sensitive, Specific, User-friendly, Rapid, Robust, Equipment-free, Delivered) criteria, being either too expensive or requiring sophisticated automates incompatible with resource-poor laboratory settings. Here, we present the preliminary results of a new immunochromatographic test (ICT) that detects anti-Aspergillus antibodies in sera in less than 30 minutes and requires minimal laboratory equipment.

Methods:
Two studies were conducted:
A 4 months single-center prospective study;
A multicenter retrospective study where five French expert hospital laboratories provided sera of patient diagnosed with an Aspergillus. 
In both study, WB (LDBIO, France) was run in addition to routine technique (except for 2 centers where it was already part of the routine techniques) without interfering in the patient’s classification. WB was performed according to manufacturer’s instruction.
In both studies the gold standard was the final multi-criteria diagnosis of Aspergillus diseases, categorized as: chronic colonization by Aspergillus in cystic fibrosis (CF) patients, allergic broncho-pulmonary aspergillosis (ABPA), CPA (including aspergilloma, fibrosing CPA and cavitary CPA), sub-acute invasive aspergillosis (SAIA) and rarer forms such as Aspergillus sinusitis, severe asthma with fungal sensitivity or Aspergillus abscess.

Results:
Prospective study: From July to October 2017, of 263 adult patients tested for anti-Aspergillus antibodies, 44 were diagnosed as Aspergillus disease cases and 219 had no-Aspergillus disease. In this prospective study the ICT showed 90.9% (40/44) sensitivity (Se) and 96.3% (211/219) specificity (Sp). Its positive and negative predictive values were 83.3% [69.2 to 92.0% CI] and 98.1% [94.9 to 99.4% CI], respectively. 
WB was not run in 7 samples (2 cases, 5 controls) due to insufficient volume. WB had 85.7% Se (36/42) and 89.7% Sp (192/214). Its positive and negative predictive values were 62.1% [48.3 to 74.2% CI] and 96.9% [93.1 to 98.8% CI], respectively.
Retrospective study: 262 cases and 188 controls had been included. ICT had 88.5% Se (232/262) and 96.3% Sp (181/188). Wb had 94.3% Se and 99.5% Sp.
Combined analysis: 306 Aspergillus diseases cases were included. ICT was positive 272 times (Se = 88.9% [84.3 to 93.5]). ICT Se was 93%, 92%, 89%, and 79% for the diagnosis of ABPA, CPA, colonization, and all others forms pooled together, respectively. The lowest Se (67%, n=24) was for the diagnosis of SAIA. ICT was negative in 392/407 controls (Sp = 96.3% [93.8 to 97.9]). WB had a Se of 93.1% (283/304 [89.5 to 95.6% CI]) and a Sp of 94.3% (379/402 [91.3 to 96.3% CI]. WB Se was 99%, 99%, 88%, and 87% for the diagnosis of ABPA, CPA, colonization, and all others forms pooled together, respectively. The lowest Se (79%, n=24) was for the diagnosis of SAIA.
Agreement between ICT and WB was excellent (Cohen’s Kappa : 0.858).

Conclusion:
This new ICT is showing promising preliminary results with adequate sensitivity and specificity for the diagnosis of Aspergillus diseases. It also comply with the ASSURED criteria, which indicates that this test could be used in middle- and low-income countries.

4 / Preliminary evaluation of a new immunochromatographic test for anti-Aspergillus antibodies detection.