Supplementary Material for: Association between constipation and the risk of Parkinson’s disease among participants in the UK Biobank

Introduction: Constipation is common in patients with Parkinson’s disease (PD), but its impact on incident PD remains uncertain. We aimed to prospectively investigate constipation symptoms and the risk of PD.
Methods: Participants without PD at baseline from the UK Biobank were included in the study. Information on the regular use of laxatives, bowel movement frequency, and the frequency of hard or lumpy stools was collected. Incident PD was defined by the ICD-10 code. Cox proportional hazards models were used to assess the association between constipation symptoms and incident PD.
Results: In the analysis of regular laxative use and PD, 490,797 participants were included and 2,735 incident PD were detected. The multivariable adjusted HR of PD in participants who regularly used laxatives was 1.99 (95% confidence interval [CI], 1.70–2.33) compared with those not. In the analysis of bowel movement frequency and hard or lumpy stools and PD, 170,017 participants were included and 519 incident PD were detected. The multivariable adjusted HRs were 2.16 (95% CI, 1.74–2.68) and 2.57 (95% CI, 2.00–3.31) for participants with a bowel movement frequency of 3–6 times/week and <3 times/week, respectively, compared with those with a bowel movement frequency of ≥7 times/week; compared with participants who never had hard or lumpy stools, multivariable adjusted HRs were 1.31 (95% CI, 1.07–1.60), 2.32 (95% CI, 1.77–3.05), and 2.94 (95% CI, 2.14–4.05) for those who sometimes had hard or lumpy stools, often had hard or lumpy stools, and most of time/always had hard or lumpy stools, respectively.
Conclusions: Constipation measured by the regular use of laxatives, bowel movement frequency, and the frequency of hard or lumpy stools was significantly associated with an increased risk of incident PD.