Objective — Lithium is an effective treatment for mood disorders, but lithium level and renal monitoring every 3 months is recommended in older patients treated with lithium to prevent serious adverse events. This study examined lithium monitoring practices in a large geriatric cohort.
Methods — This population-based cohort study (N = 11,006) used linked health care administrative databases. Older lithium users (n = 5,503; mean age = 70.6 years) in Ontario, Canada, enrolled between April 1, 2002, and March 31, 2014, were propensity score matched 1:1 to valproate users (n = 5,503). The frequency with which serum lithium levels were monitored and renal and endocrine laboratory testing was done during a 1-year follow-up period was examined.
Results — The baseline characteristics of the 2 groups were similar. At least 1 serum lithium concentration recorded within 90, 180, and 365 days of follow-up was present in 24.1%, 42.4%, and 66.8% of lithium users, respectively. Corresponding numbers for serum creatinine were 29.6%, 50.4%, and 75.4%, respectively. While serum creatinine monitoring (hazard ratio [HR] = 1.19; 95% CI, 1.12–1.27; P < .001), thyroid-stimulating hormone monitoring (HR = 1.47; 95% CI, 1.37–1.58; P < .001), and calcium testing (HR = 1.15; 95% CI, 1.02–1.29; P = .018) were statistically higher in lithium compared to valproate users, absolute differences between groups were not clinically meaningful.
Conclusions — In a geriatric Canadian community sample, lithium monitoring was infrequent and inconsistent with international standards that call for screening of lithium levels and renal function every 3 months.