Inter-rater reliability and validity of automated impedance manometry analysis and fluoroscopy in dysphagic patients after head and neck cancer radiotherapy
Szczesniak, Michal Marcin
Maclean, Julia C F
Cook, Ian James
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Introduction: Automated Impedance manometry (AIM) pressure-flow analysis is novel non-radiological method to analyse swallowing function based on impedance-pressure recordings of pharyngeal swallows. In a population of dysphagic head and neck cancer patients, we evaluated the reliability and validity of the AIM-derived swallow risk index (SRI) and a novel measure of post-swallow residue (iZn/Z) by comparing it against videofluoroscopy as the gold standard for assessing aspiration and post-swallow residue risk. Materials and Methods: Three blinded experts classified 88 videofluoroscopic swallows from 16 patients for aspiration and the degree of post-swallow residue using validated videofluroscopy scales. Pressure-impedance recordings of the swallows were also analysed using automated analysis software by one expert and two novice observers who derived the SRI and iZn/Z. Inter-observer concordance for videofluoroscopic and AIM measures was assessed using intraclass correlation coefficients (ICC). Patient SRI and iZn/Z measurements were compared with videofluoroscopy scores and control subjects to determine validity for detecting clinically relevant swallowing dysfunction. . Results: Among individual swallows, agreement among observers assessing presence of penetration and aspiration on videofluoroscopy was modest (ICC 0.57). Agreement among observers for AIM-derived swallow risk index (SRI) and the iZn/Z was good (ICC of 0.71 and ICC of 0.82 respectively). When compared with age-matched controls the SRI was higher in patients with aspiration (mean diff. 28.6, 95% CI [55.85 1.355], p<0.05). The iZn/Z was increased, suggesting greater post-swallow residues, in both patients with aspiration (Δ244 [419.7, 69.52, p<0.05]) and penetration (Δ240 [394.3, 85.77, p<0.05]) compared to controls. Discussion: AIM based measures of swallowing function have better inter-rater reliability than comparable fluoroscopically-derived measures. These measures can be easily determined and are objective markers of clinically relevant features of disordered swallowing following head and neck cancer therapy.
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