Clinical implications of ANCA positivity in a hospital setting: a tertiary center experience
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Clinical implications of ANCA positivity in a hospital setting: a tertiary center experience Bashar Fteiha1 · Alon Bnaya1,2 · Marwan Abu Sneineh1 · Gideon Nesher1,3,4 · Gabriel Simon Breuer1,3,4 Received: 22 July 2020 / Accepted: 25 September 2020 © Società Italiana di Medicina Interna (SIMI) 2020
Abstract ANCA testing plays an established critical role in the diagnosis of ANCA Associated vasculitis (AAV). The spectrum of diseases associated with positive ANCA has recently broadened, thus calling into question the diagnostic implications of ANCA positivity in a hospital setting. We retrospectively studied all adult patients who had a positive ANCA test (by Indirect Immunofluorescence (IIF), ELISA or both) performed over the span of 19 years. Subjects were then divided into discordant (positive on one assay) and concordant ANCA (positive on both assays) groups based on their ANCA positivity status. The two groups were then compared with regards to their demographic, clinical and laboratory characteristics, the indication for ANCA testing in both groups and their final diagnoses. Of the 9189 ANCA tests ordered during the 19-year span of the study, 389 (4.2%) were positive. Two hundred and forty subjects met the exclusion criteria (patients aged less than 18 years or the lack of clinical and laboratory data in the medical file) thus resulting in a final cohort of 149 subjects. Of them, 122 subjects had discrepant ANCA results and 27 had matching ANCA results. Most cases in the discrepancy group were IIF positive and ELISA negative (86.8%). The diagnosis of AAV was highly unlikely in cases with discrepant IIF and ELISA serologies compared to cases with matching IIF and ELISA serologies (4.1% versus 44.4%, p value 15 IU/ml)
122 65.35 ± 19.868 n (%) 54 (44.3%) n (%) 107 (87.7%) 12 (9.8%) 3 (2.5%) n (%) 11 (9%) 65 (53.3%) 28 (23%) 29 (23.8%) 14 (11.5%) 16 (13.1%) 18 (14.9%) Mean ± SD 11.31 ± 2.26 1.85 ± 2.81 7.15 ± 7.28 120 (96.5–147) 28 (23–36) 54.14 ± 38 6 (10.2%)
27 61.07 ± 19.810 n (%) 13 (48.1%) n (%) 21 (77.8%) 6 (22.2%) 0 (0%) n (%) 2 (7.4%) 11 (40.7%) 2 (7.4%) 5 (18.5%) 3 (11.1%) 6 (22.2%) 2 (7.4%) Mean ± SD 10.1 ± 2.16 2.14 ± 3.36 12.65 ± 6.54 108 (96–148) 32 (24.5–41.5) 82.4 ± 36.3 5 (31.3%)
NA 0.556 † 0.713 § 0.155 §
1.000 Ƒ 0.238 § 0.108 Ƒ 0.556§ 1.000 Ƒ 0.227 § 0.532 Ƒ 0.019 † 0.56 † 0.002 † 0.691 ‡ 0.242 ‡ 0.012 † 0.05 ƒ
C complement, CRP C-reactive protein, ESR erythrocyte sedimentation rate, HB hemoglobin, AAV ANCAAssociated vasculitis, RF rheumatoid factor
a
Autoimmune disease— established autoimmune diseases including SLE, IBD, vasculitis other than AAV
† ‡
Independent samples t test Mann–Whitney U test
ƑFisher’s exact test
§
Chi-square test
13
Internal and Emergency Medicine
Fig. 1 ANCA positive tests assessed by concordance. *No cases of IIF negative anti PR3positive cases were found
149 ANCA posive tests
27 Concordant tests
122 Discordant tests 106 IF posive
16 ELISA posive
ELISA negave
21 an-PR3 posive**
IF negave 14 CANCA posive
28 P-ANCA pos
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