Page 22 - ITPS-5-2

16 INNOSC Theranostics and Pharmacological Sciences, 2022, Vol. 5, No. 2 Govender and Hodkinson

Table 1. 1999 international consensus statement Laboratory Services (NHLS) at a state-sector
guidelines of indications for ANCA testing* [1] tertiary hospital over 12 months. Case records

i. Glomerulonephritis, especially rapidly progressive GN were reviewed, and clinical and demographic
features (including self-reported ethnic group), the
ii. Pulmonary hemorrhage, especially pulmonary renal
syndrome department requesting the test, and comorbidities
iii. Cutaneous vasculitis with systemic features were collated. The indication for each ANCA test
was assessed against the International Consensus
iv. Multiple lung nodules Statement of 1999.
v. Chronic destructive disease of the upper airways The revised 2017 international consensus on
vi. Long-standing sinusitis or otitis ANCA testing recommends the use of high-quality
vii. Subglottic tracheal stenosis immunoassays as the preferred first screening
viii. Mononeuritis multiplex or other peripheral method for granulomatosis with polyangiitis (GPA)
neuropathies and microscopic polyangiitis [2], which remains
ix. Retro-orbital mass unchanged in the 2020 consensus statement [6].
x. Scleritis The recommendations were based on a multi-
Note: *when there is no other obvious cause. center European Vasculitis Study Group evaluation
which demonstrated that these assays had a higher
62% [3]. Encouragingly, studies show that AAV diagnostic performance in comparison to manual
is seldom missed when testing is restricted to and automated indirect immunofluorescence [7].
indications listed in the 1999 clinical guidelines [3]. While the consensus statement does not specify
AAV seems to be rare in African populations. Only a particular type of immunoassay to be used, a
a limited number of studies on ANCA antibodies or recent review from the Netherlands has indicated
AAV in Africa have been reported, most likely due to that, for routine screening, diagnosis, and follow-
a combination of a low index of suspicion of AAV and up, quantitative assays measuring ANCA levels
a lack of appropriate laboratory facilities [4]. Among are associated with higher likelihood ratios and
a group of 60 West Africans, 6.7% of patients with a more definitive diagnosis [8]. On the other
chronic infections (tuberculosis [TB] and malaria) hand, qualitative immunoassays can be used
tested positive for anti-myeloperoxidase (MPO). In for confirmation and rapid testing [8], generally
contrast, no ANCA antibodies were detected among interpreted using a single cut-off value.
healthy Africans [5]. The NHLS utilized a fluorescence enzyme-linked
The rising cost of laboratory investigations and immunosorbent assay sandwich immunoassay for
equitable distribution of healthcare resources has ANCA testing. The specific method employed
become important issues worldwide, with both was the EliA IgG assay, performed on the Phadia
social and political implications. In South Africa, 250 (Thermofisher). This in vitro qualitative
cost-effectiveness is a major criterion in developing measurement detects IgG antibodies directed against
clinical policies. We audited all ANCA tests ordered proteinase 3 (PR3) and MPO in human sera. Before
in a tertiary academic hospital to assess adherence analysis, the sample preparation includes allowing
to indications for testing, evaluate the diagnostic the serum to clot at room temperature, followed by
accuracy of the test, and review the positive ANCA centrifugation at 2200× g for 15 min. The serum
test results, aiming to decrease hospital costs and is then drawn off, and aliquots are transferred into
avoid inappropriate specialist referrals. The Human appropriately labeled tubes. The aliquot samples
Research Ethics Committee of the Faculty of Health are immediately analyzed. The cutoff values (as per
kit manufacturer) for anti-PR3 and anti-MPO are
Sciences, University of Cape Town, approved the 1.9 U/ml and 3.4 U/ml, respectively.
study (HREC reference number 443/2018).
Descriptive statistics and normally distributed
2. Methods variables are presented as means with standard
deviations, and sensitivity, specificity, PPV, and
A retrospective record review was performed on all NPV were calculated. Analysis was conducted
ANCA tests ordered through the National Health using IBM SPSS Statistics V26.

©2022 AccScience Publishing