Abstract: SA-PO872
Baclofen and the Risk of Encephalopathy in Older Adults with CKD: A Population-Based Cohort Study
Session Information
- CKD: Pharmacoepidemiology
November 09, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: CKD (Non-Dialysis)
- 2101 CKD (Non-Dialysis): Epidemiology, Risk Factors, and Prevention
Authors
- Muanda, Flory Tsobo, Western University/ICES KDT, London, Ontario, Canada
- Garg, Amit X., London Health Sciences Centre, London, Ontario, Canada
Group or Team Name
- ICES-KDT
Background
Importance: Baclofen, a popular muscle relaxant, undergoes renal clearance and can accumulate in patients with low kidney function. Over 30 case reports link baclofen use to encephalopathy in patients with chronic kidney disease (CKD).
Objectives: The primary objective was to compare the 30-day risk of encephalopathy in patients with CKD newly prescribed a high vs low dose of baclofen (≥20 vs <20 mg/day). The secondary objective was to compare the risk in baclofen users vs non-users.
Methods
Design: Population-based cohort study using linked healthcare data.
Setting: Ontario, Canada (2007–2018).
Participants: Older adults with CKD (defined as an estimated glomerular filtration rate [eGFR] <60 mL/min/1.73 m2 but not on dialysis). The primary cohort was restricted to new baclofen users; the secondary cohort included both new users and non-users.
Exposure: Oral baclofen (≥20 mg/day vs <20 mg/day).
Main Outcome and Measure: Hospital admission with encephalopathy, defined as a main diagnosis of delirium, disorientation, transient cerebral ischemic attack, alteration of awareness, or dementia. Inverse probability of treatment weighting on the propensity score was used to balance comparison groups on indicators of baseline health. Weighted risk ratios (wRR) were obtained using modified Poisson regression and weighted risk differences (wRD) using binomial regression.
Results
The primary cohort included 15,942 patients with CKD (61% women; median age 77); 9707 (61%) patients started baclofen at ≥20 mg/day and 6235 (39%) at <20 mg/day. The primary outcome, hospital admission with encephalopathy, occurred in 108 (1.11%) patients in the high-dose group and in 26 (0.42%) patients in the low-dose group. The wRR was 3.54 (95% CI, 2.24–5.59) and the wRD was 0.80% (95% CI, 0.55%–1.04%). In subgroup analysis, the absolute risk increased progressively as eGFR declined. In patients with eGFR<30 mL/min/1.73 m2, the wRR was 4.26 (95% CI, 1.77–10.25) and the wRD was 2.90% (95% CI, 1.30%–4.49%). In the secondary comparison with 284,263 non-users, both low-dose and high-dose users had a higher risk of encephalopathy: wRR, 5.90 (95% CI, 3.59–9.70) and 19.8 (95% CI, 14.0–28.0), respectively.
Conclusion
Baclofen should be used cautiously or avoided in patients with CKD.
Funding
- Government Support - Non-U.S.