Page 21 - ITPS-5-2

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INNOSC Theranostics and Pharmacological Sciences 2022 Vol. 5 (No. 2) pp: 15-21

INNOSC Theranostics and Pharmacological Sciences

Journal homepage: https://accscience.com/journal/ITPS

RESEARCH ARTICLE
Poor Adherence to Indications for Anti-neutrophil Cytoplasmic

Antibody Testing in a South African Tertiary Hospital

Ramona Govender, Bridget Hodkinson*

Division of Rheumatology, Groote Schuur Hospital, University of Cape Town, Cape Town, South Africa
*Corresponding author: Bridget Hodkinson, Email: drbridget@gmail.com
Received: January 26, 2023; Accepted: June 26, 2023; Published: July 12, 2023 DOI: https://doi.org/10.36922/itps.v5i2.338
Copyright: Author(s). This is an open-access article distributed under the terms of the Attribution Non-Commercial 4.0 International
4.0 (CC BY-NC 4.0), which permits all non-commercial use, distribution, and reproduction in any medium, which provided that
the original work is properly cited.

Abstract:
Appropriate use of laboratory investigations is increasingly important in resource-constrained environments. In this study, we
reviewed the anti-neutrophil cytoplasmic antibody (ANCA) testing practices in a tertiary hospital in South Africa. A retrospective
file review was conducted, encompassing all ANCA tests ordered over 12 months, including both inpatients and outpatients.
Sociodemographic and clinical details were extracted from the patient records. All requests were assessed against the International
Consensus Statement of 1999, which provides clinical guidelines for the indications for ANCA testing. Of the 945 ANCA tests
requested, 790 patient records were reviewed, while 155 records were found to be missing, and 62 patients had multiple tests. Only
193 patients (24.4%) had indications for ANCA testing that met the guidelines. The most common tests done outside guideline
indications were critical limb ischemia (9.6%), stroke (7.3%), uveitis (5.7%), renal impairment (4.9%), and interstitial lung disease
(4.4%). Among the patients, ten (1.3%) were diagnosed with ANCA-associated vasculitis (AAV), of whom nine had renal-limited
vasculitis. Twenty-six patients tested positive for ANCA without any evidence of AAV. Of these false positives, 10 (38.4%) were
human immunodeficiency virus (HIV) positive, 3 (11.5%) had tuberculosis (TB), and 3 (11.5%) had other autoimmune diseases.
The annual cost of ANCA tests amounted to ZAR274,046, with ZAR17,490 spent on duplicate testing and ZAR208,275 on non-
indicated clinical conditions. The study revealed that ANCA testing was performed outside standard guidelines in three-quarters
of requests, and duplicate testing was common, resulting in large cost implications. Chronic infections, such as HIV and TB, and
autoimmune conditions accounted for half of the false-positive tests. The findings suggest that training of clinicians is likely to
reduce unnecessary tests.
Keywords: Anti-neutrophil cytoplasmic antibody, ANCA-associated vasculitis, Gated testing

1. Introduction 2017 provided clinical guidelines of indications
for ANCA testing (Table 1) [1,2]. The aim of these
Anti-neutrophil cytoplasmic antibodies (ANCAs) guidelines is to increase the positive predictive
are important diagnostic tools for ANCA- value (PPV) of ANCA testing by limiting the test
associated vasculitis (AAV), a group of necrotizing to patients with clinical features suggestive of
small vessel vasculitis characterized by few AAV. It has been shown that ANCA tests have a
or no immune deposits. Due to the high false- PPV of 54% and a negative predictive value (NPV)
positive rate for indiscriminate ANCA testing, the of 99% in conventional clinical settings, but with
International Consensus Statements of 1999 and the application of guidelines, PPV is increased to

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