Photo Credit: Liubomyr Vorona

A component analysis defined two constructs of respiratory dysfunction in Parkinson’s disease—dyspnea and dystussia—and factors associated with the constructs.

About 44% of patients with Parkinson’s disease (PD) report symptoms of respiratory dysfunction, according to a study published online in the Journal of Neurology.

“Our analyses revealed two internally consistent subdomains that represent respiratory dysfunction, namely dyspnea and dystussia,” the researchers wrote.

Previous studies indicate a prevalence rate of respiratory dysfunction in PD ranging from 18% and 94%. The present study investigated the prevalence of respiratory dysfunction in a large cohort of patients with PD.

A total of 939 patients with PD completed a questionnaire about their experience with respiratory dysfunction, which researchers defined as at least one of the following symptoms: breathing difficulties, breathlessness/shortness of breath, tightening of the chest, frequent throat clearing, frequent coughing, and coughing difficulties. Participants also provided information on motor symptoms, swallowing, quality of life, COVID-19, and anxiety, as well as sociodemographic data.

More than half of the participants (60.8%) were men, and the mean age was 70 years.

Constructs of Respiratory Disease in PD

After researchers excluded participants with pulmonary disease or COVID-19 symptoms, the prevalence of respiratory dysfunction in patients with PD was 42.0%.

A principal component analysis conducted to define composite constructs of respiratory dysfunction resulted in two constructs: (1) dyspnea, which represented the symptoms of breathing difficulties, shortness of breath, and tightening in the chest; and (2) dystussia, which represented coughing and throat-clearing symptoms.

Multivariable logistic regression models identified several factors that were independently associated with dyspnea, including pre-existing pulmonary disease (odds ratio [OR], 7.12), longer disease duration (OR, 1.35), female sex (OR, 1.39), greater self-reported rigidity (OR, 1.16), higher BMI (OR, 1.04), and anxiety (OR, 1.04).

Factors with independent associations with dystussia included COVID-19 symptoms (OR, 2.20), pre-existing pulmonary disease (OR, 1.81), swallowing problems (OR, 1.48), and speech difficulties (OR, 1.02).

The identification of the dyspnea and dystussia subdomains and their determinants should enable clinicians to screen for and recognize respiratory dysfunction in patients with PD at an early stage and to address it accordingly, the authors advised.

“Both dopaminergic medication and non-pharmacological interventions (respiratory training) can improve respiratory function and have the potential to prevent late-stage complications,” the researchers wrote. “This presumably requires a multidisciplinary approach and, given that multiple factors are related to respiratory dysfunction, a personalized approach as well.”