ABSTRACT
BACKGROUND: Exit site infections are a risk factor for the development of peritonitis in patients on long-term peritoneal dialysis. Visual assessments of an exit site utilising currently available tools (Twardowski and Mid-European Pediatric Peritoneal Dialysis Study Group (MEPPS)) are necessary to objectively characterise the appearance of an exit site. The aim of this study was to assess the interobserver agreement of exit site evaluations utilising both exit site scoring tools. METHODS: Exit site evaluations were independently performed by two evaluators during outpatient visits at 13 sites within the Standardizing Care to Improve Outcomes in Pediatric End Stage Kidney Disease collaborative. The frequency and percentage of evaluations where both reviewers agreed were calculated. A sub-analysis was performed looking at evaluations where disagreement occurred. RESULTS: A total of 371 paired exit site evaluations were collected over 6 months. For the majority of evaluations (range: 78%-97% Twardowski, 78%-97% MEPPS), both reviewers agreed that no abnormality was present across all domains. When the analysis was restricted to evaluations where at least one reviewer noted an abnormality, interobserver agreement fell across all domains (range: 31%-61% Twardowski, 56%-66% MEPPS). Disagreements more commonly occurred regarding the presence versus absence of an abnormality, rather than a difference in the severity of an abnormality. CONCLUSIONS: Whereas interobserver agreement is high when the appearance of a peritoneal dialysis catheter exit site is characterised as 'normal', interobserver disagreement is common when the appearance of the exit site is 'abnormal'. Further work is warranted to improve interobserver agreement of exit site assessments and to identify domains conferring an increased risk of infection.
ABSTRACT
PURPOSE: Indirect immunofluorescence (IIF) on the human epithelial cell-line HEp-2 (or derivatives) serves as the gold standard in antinuclear antibody (ANA) screening. IIF, and its evaluation, is a labor-intensive method, making ANA testing a major challenge for present clinical laboratories. Nowadays, several automated ANA pattern recognition systems are on the market. In the current study, the EUROPattern Suite is evaluated for its use in daily practice in a routine setting. METHODS: A total of 1033 consecutive routine samples was used to screen for ANA. Results (positive/negative ANA screening, pattern identification and titer) were compared between software-generated results (EUROPattern) and visual interpretation (observer) of automatically acquired digital images. RESULTS: Considering the visual interpretation as reference, a relative sensitivity of 99.3% and a relative specificity of 88.9% were obtained for negative and positive discrimination by the software (EPa). A good agreement between visual and software-based interpretation was observed with respect to pattern recognition (mean kappa: for 7 patterns: 0.7). Interestingly, EPa software distinguished more patterns per positive sample than the observer (on average 1.5 and 1.2, respectively). Finally, a concordance of 99.3% was observed within the range of 1 titer step difference between EPa and observer. CONCLUSIONS: The ANA IIF results reported by the EPa software are in very good agreement with the results reported by the observer with respect to being negative/positive, pattern recognition and titer, making automated ANA IIF evaluation an objective and time-efficient tool for routine testing.
ABSTRACT
The ANCA consensus prescribes screening by indirect immunofluorescence on neutrophils. We evaluated the first automated ANCA-pattern recognition system. C-ANCA (n = 39) and P-ANCA (n = 40) samples were selected from patients with ANCA-associated vasculitis (AAV). Non-AAV controls included sera from healthy controls (n = 40), sera with possible interfering antibodies (n = 46), or miscellaneous ANCA reactivity (n = 31). ANCA slides were analysed by AKLIDES and routine fluorescence microscopy. The C-ANCA pattern was recognized by routine microscopy in 92% and 97% on ethanol- and formalin-fixed slides, respectively. AKLIDES reported C-ANCA in 74% and 95%, respectively. P-ANCA was recognized by routine microscopy on ethanol-fixed neutrophils in 90%, while AKLIDES reported P-ANCA in 80%. Typically, only 65% and 33% of these samples showed the expected C-ANCA on formalin-fixed neutrophils by routine microscopy and AKLIDES, respectively. A C- or P-ANCA pattern was observed on ethanol-fixed neutrophils in 28% and 23% of the controls by routine microscopy and AKLIDES, respectively. Only 5% of the controls revealed C-ANCA on formalin-fixed neutrophils by routine microscopy and AKLIDES. Altogether, automated ANCA-pattern recognition by AKLIDES is promising. Distinction of C- and P-ANCA is good, but sensitivity on ethanol-fixed neutrophils needs improvement. When optimized, pattern recognition software may play an important role in AAV diagnostics.
