Constipation and risk of Parkinson's disease: A Danish population-based cohort study

To examine long-term associations between constipation and Parkinson's disease (PD) in men and women, we conducted a population-based cohort study using prospectively collected registry data on hospital contacts for constipation and PD, stratified by follow-up time and sex.

We linked Danish registries to construct a cohort of all patients in Denmark with an outpatient hospital diagnosis of constipation 1995-2012 and a matched general population comparison cohort. Using Cox regression, we computed hazard ratios (HRs) for PD and corresponding 95% confidence intervals (CIs), adjusting for potential confounders, stratified by sex and follow-up time.

The 31,905 patients with constipation had a higher risk of PD than 159,092 comparison cohort members (adjusted (a) HR = 3.03, 95% CI 2.50-3.66), which was sustained to 11-15 years follow-up (aHR = 3.65, 95% CI 1.67-7.95). Increased risk was apparent in both sexes but stronger in men [aHR = 3.52 (2.67-4.64] than women [aHR = 2.64 (95% CI 2.02-3.44].

In this large population-based cohort study, constipation was associated with sustained increased risk of a PD diagnosis, and the relative risk was higher for men than for women.