Usefulness of citric cough test for screening of silent aspiration in subacute stroke patients: a prospective study

Abstract

Objective: To detect silent aspiration in a homogeneous sample of stroke patients using the citric acid cough test.

Design: Prospective study.

Setting: Public university tertiary hospital.

Participants: Consecutive subacute stroke patients (N=134; 74 men, 60 women; mean age ± SD, 62.2±11.9y; 11.7±9.9d after stroke) who had complained of dysphagic symptoms, referred for rehabilitation from December 2010 to October 2012.

Intervention: All patients were administered a citric acid cough test and underwent a videofluoroscopic swallowing study (VFSS). A reduced or an absent response on the citric acid cough test was considered when cough peaks were ≤4. A control group of healthy volunteers was also screened.

Main outcome measures: The citric acid cough test results were compared with the VFSS results, which were used as a criterion standard.

Results: There were 36 patients with a positive citric acid cough test, of which the VFSS revealed penetration in 14 cases (38.9%), aspiration in 5 (13.9%), silent aspiration in 5 (13.9%), and normality in 12 patients (33.3%). The sensitivity and specificity indexes for the reliability of citric acid cough test as a screening method for silent aspiration in comparison with the VFSS were .19 and .71, respectively. Other comparisons were made between silent aspirators (Penetration Aspiration Scale=8) and different subgroups of patients, but values remained poor.

Conclusions: The citric acid cough test using 1.0 (weight by volume)% for 1 minute does not seem to be a useful standalone tool to screen for silent aspiration in subacute stroke patients with suspected dysphagia.

Keywords: Cough; Deglutition disorders; Diagnosis; Rehabilitation; Respiratory aspiration.