Pill swallowing in Parkinson's disease: A prospective study based on flexible endoscopic evaluation of swallowing

Background: This study evaluates the prevalence, characteristics, and predictors of the difficulty of swallowing medication in Parkinson's disease (PD). Methods: In this prospective controlled, cross-sectional cohort study, the ability to swallow four different placebos was assessed using flexible endoscopic evaluation of swallowing (FEES) in 118 PD patients and 32 controls. The association between a patient's swallowing ability for each pill and water, patient characteristics and dopaminergic response was examined. The value of two swallowing screening questions was also evaluated. Results: Substantially impaired ability to swallow pills was found in 28% (n = 33/118) of patients and 16% (n = 5/32) of controls (p = 0.18). Higher disease severity was associated with more problems with swallowing pills (p = 0.03), but PD patients with short disease duration (< 2 years), low H&Y stage (1-2), and younger age (< 70 years) were also affected (each at least in 20%). Capsules were the easiest to swallow while oval tablets were the most difficult (p < 0.01, r = 0.21). Most patients (73%, n = 24/33) presented with swallowing problems only for a single formulation. Aspiration of water was found in 48% of patients, suggesting a possible increased risk of aspiration when taking dissolved tablets. Standardized questionnaires showed insufficient sensitivity (52% both) but fairly good specificity (69-74%) for dysphagia of pills. Dysphagia for medication was not associated with a lack of dopaminergic response. Conclusions: Dysphagia of medication occurs preferentially in advanced disease stages. An assessment of pill swallowing using FEES is suggested at least in patients reporting swallowing problems. Capsules might be preferentially used when dysphagia is suspected.