Lithium usage and renal function testing in a large UK community population; a case-control study.

Objective: This study investigates the prevalence of lithium use, monitoring practice and associated effects on renal function in a large UK community sample.

Method: A large population-based renal function database was cross-referenced with a general practitioner database of 404,673 patients. The renal function of patients prescribed lithium during the 2-year period was compared with that of matched controls. The renal monitoring patterns of these cases were investigated in a naturalistic observational study. Data underwent parametric testing - continuous variables by analysis of variance, with appropriate adjustment, and categorical outcomes by χ(2) testing. Block analysis of variance was undertaken on case-control data.

Results: A total of 422 patients in the database were prescribed lithium. Renal function monitoring in accordance with published guidelines occurred in 69% of patients. Patients taking lithium had a significantly higher serum creatinine (5.8 μmol/L, P<.001) and lower glomerular filtration rate (5.9 ml/min, P<.001) when compared to matched controls.

Conclusions: This is the first study carried out in a large community sample. Lithium remains widely prescribed in the community setting. The study confirms that lithium has a statistically and clinically significant negative effect on renal function. Despite published guidelines and recognition of the importance of serial measurements, monitoring of renal function is inconsistent.