Association between gout, hyperuricaemia and Parkinson's disease risk: a cohort study in western Sweden (2001-2017).

Objectives: Neurodegenerative diseases including Parkinson's disease (PD) have been found to be associated with gout and hyperuricaemia in multiple studies but with conflicting results. We set out to determine the incidence and relative risk of PD in all gout individuals in western Sweden from 2001 to 2016 compared with controls. Blood urate levels in gout patients with and without incident PD were compared.

Methods: All individuals with a gout diagnosis between 2001 and 2016 were identified and matched to population non-gout controls; individuals with prevalent PD were excluded. PD incidence rates were compared between cases and controls. The effect of gout on the risk of PD was calculated using Cox regression. The plasma urate level was identified for all gout cases.

Results: In the 42 260 gout cases (67% male) and 174 747 controls (65% male) the incidence rate for PD was 1.38 per 1000 person-years in gout cases compared with 1.73 in controls, producing a significant decreased incidence rate ratio of 0.80 (95% CI 0.72, 0.90; P < 0.0001). Cox regression also showed a significant decreased risk for PD in the gout patients [hazard ratio 0.77 (95% CI 0.69, 0.86), P < 0.0001]. Gout patients with incident PD had significantly lower plasma levels of urate compared with gout patients without incident PD.

Conclusion: The findings in this study show that gout is inversely associated with PD and in gout patients urate levels were inversely associated with the risk of PD. If future research proves this association to be causal it would have clinical implications in lowering urate in gout subjects at high risk of PD.