Chronic Pain in Autosomal Dominant Polycystic Kidney Disease and the Long-Term Effects of Increasing Water Intake.

Abstract

Background: Chronic pain is a debilitating consequence of ADPKD, and the longitudinal progression of pain has not been well-defined. Previous studies suggested that increased water intake may reduce ADPKD-related pain.

Methods: This was a post-hoc analysis of the PREVENT-ADPKD trial, where pain characteristics were assessed biannually using the HALT-PKD pain questionnaire. This 3-year trial allocated 184 participants to either increased water intake to reduce urine osmolality to ≤270 mosmol/kg (n=92) or to continue usual water intake (n=92).

Results: At baseline, two-thirds (66%) and one-third (33-38%) of participants experienced back and abdominal pain respectively. By multivariable analyses, baseline back and abdominal pain were associated with a higher eGFR (75-90ml/min/1.73m2). Participants allocated to the usual water intake group experienced no progression in back or abdominal pain over three years. In the increased water intake group, back pain was transiently reduced by 33% between 12-18 months (p=0.04), but this improvement was not sustained over three years (p=0.21). Increased water intake had no impact on the progression of abdominal pain. By multivariable analyses (age, sex, Mayo class, eGFR) of pain progression, participants with lower eGFR (30-45ml/min/1.73m2) were more likely to experience an increase in abdominal pain over three years (p=0.03). Participants allocated to the increased water intake group had reduced analgesia use (16% vs 31%, p<0.001).

Conclusions: Chronic back and abdominal pain were common and associated with higher eGFR at baseline, while abdominal pain progression was more frequent among participants with lower eGFR. Increased water intake was associated with reduced analgesic use, however, as pain outcomes were not the primary endpoint of the parent trial, these findings should be considered exploratory.