Patients

The study retrospective cohort study using prospectively collected data was approved by the Institutional Research Board of Stanford University and was conducted at the Neuro-gastroenterology and Motility Center of Silicon Valley Gastroenterology, in Mountain View, California, USA. The protocol was considered exempt from the need for individual informed consent from participating patients.

We included consecutive patients with PD who were all evaluated because of constipation and defaecation difficulties and agreed to undergo HRAM with BET and WMC. All patients had recurrent symptoms persisting for >6 months, while those with faecal incontinence reported recurrent uncontrolled passage of faecal material, not related to a temporary diarrhoeal event.⁹ All patients fulfilled the Rome IV criteria for functional constipation defined as any two of the following features: straining, lumpy hard stools, sensation of incomplete evacuation, use of digital manoeuvres, sensation of anorectal obstruction or blockage with 25% of bowel movements, and decrease in stool frequency (<3 bowel movements per week).¹⁰

Patients <18 years old, those with known gastrointestinal pathology (ie, inflammatory bowel disease, stricture), other systemic illnesses affecting motility (ie, scleroderma) and those who had previously undergone respective gastrointestinal surgery were excluded.

The study patients were part of a total cohort of 95 patients with PD referred and evaluated at our centre during the study period for various gastrointestinal symptoms, predominantly constipation, dysphagia, nausea, early satiety, malnutrition and weight loss (figure 1). All study participants had previously undergone colonoscopy or sigmoidoscopy without revealing any structural explanation for their constipation. Symptoms were recorded on questioning and formal quantitative questionnaire-based assessment. Neurological assessment of the patients was made using the previously validated modified Hoehn and Yahr scale (score 0–5)¹¹ and the duration of PD was recorded in years since the time of diagnosis. Variable regimens of PD therapies were used and not discontinued for the conduct of any of the tests performed. Such therapies included carbidopa-levodopa, carbidopa-levodopa-entacapone, pramipexole, ropinirole, rotigotine, rasagiline, trihexyphenidyl, selegiline, tolcapone, rivastigmine and amantadine in various doses and schedules (table 1). Prospectively collected clinical, transit and manometric data from these patients were then analysed. Of note, the study, albeit community-based, was on a referral population to a gastrointestinal motility unit.

List of Parkinson's disease drugs used by the patients in the study (n=66) and the respective number of users

Many patients were using combination therapies.

Study flow diagram. Of the entire population of 95 patients with PD referred, 66 were studied with HRAM and 53 of those with WMC as well. CC, chronic constipation; HRAM, high-resolution anorectal manometry; PD, Parkinson's disease; WMC, wireless motility capsule.