Diagnosis of Allergic Bronchopulmonary Aspergillosis: A Case-Based Approach

Sahajal Dhooria; Ritesh Agarwal

Disclosures

Future Microbiol. 2014;9(10):1195-1208. 

In This Article

What Should Be the Basis for Staging ABPA?

ABPA is staged both clinically and radiologically, the former has therapeutic and the latter prognostic implications.[45] Patterson et al. has classified ABPA into five clinical stages;[36] however, this staging was limited by the lack of precise definitions at each stage. The latest guidelines have recommended a new staging system (Table 1) to circumvent the ambiguities of the previous system. Certain points deserve special mention. ABPA is now classified into seven stages with stages 1 and 5 having substages. The stages do not represent sequential temporal regression and a patient may revert to a lower stage with treatment or time. Up to half of the patients may experience an exacerbation of the disease usually within 1–2 years.[36,37,39] It is important to note that IgE levels do not return to normal values even in patients with remission.[67] Thus, repeated evaluation of IgE should be performed to characterize the 'new baseline' value, which is then used for defining exacerbations. A prolonged remission does not imply a cure as exacerbations of the disease can occur several years after remission. Even in stage 6 (advanced ABPA), patients may require therapy as the disease can remain clinically and immunologically active.[74]

Patterson et al. have classified ABPA radiologically into two stages: ABPA-S and ABPA with central bronchiectasis (ABPA-CB), with ABPA-S representing patients without pulmonary damage.[37] Kumar et al. divided cases of ABPA into ABPA-S, ABPA-CB and ABPA with other radiologic findings (ABPA-CB-ORF) based on findings on CT chest scan.[75] In a large study, no difference was found among the radiologic stages of ABPA in terms of duration of illness, severity of asthma and serologic findings.[39] However, severity of bronchiectasis (based on the number of segments affected by bronchiectasis on HRCT) and the presence of HAM were predictors of relapse and failure to achieve complete remission.[13] These findings prompted Agarwal et al. to propose a new classification scheme based on HAM, thus creating three classes: ABPA-S, ABPA-CB and ABPA-CB-HAM.[9] In this study, the older classification schemes were compared with the one based on HAM and it was found that HAM most consistently predicted immunological severity in ABPA.[9] The long-term outcome of ABPA-S is good (despite frequent relapses), and in one study no patient developed bronchiectasis with appropriate management.[76] The radiologic classification proposed in the recent guidelines takes cognizance of all the classification schemes and divides ABPA radiologically into four stages (Table 2).

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