Lithium and the risk of chronic kidney disease: A population‐based case–control study

The association between lithium use and chronic kidney disease (CKD) needs further evaluation. We aimed to investigate this association using Danish nationwide healthcare registers and routinely collected plasma creatinine measurements from the Funen Laboratory Cohort. We conducted a case–control study nested within the population of Funen, 2001–2015. Incident cases of CKD (estimated glomerular filtration rate <60 ml/min/1.73m(2); n = 21 432) were matched with four CKD‐free controls on age, sex and calendar time (n = 85 532). We estimated odds ratios (OR) for the association between lithium exposure and CKD using conditional logistic regression models, adjusted for known risk factors for CKD. Ever‐use of lithium was associated with an increased risk of CKD (adjusted OR [aOR]: 1.57; 95% confidence interval [CI]: 1.33–1.85). A stronger association was seen with current use of lithium (aOR: 1.92; 95%CI: 1.58–2.33) and long‐term use of lithium (>10 years: aOR: 3.02; 95%CI: 2.00–4.56). Furthermore, we found evidence of a dose–response relationship between cumulative dose of lithium and the risk of CKD. In conclusion, the use of lithium, especially long‐term, is associated with an increased risk of CKD, although the extent to which detection bias and confounding by indication contribute to the association is unclear. Monitoring of kidney function in lithium users remains mandatory to identify individuals in which switching to alternative medications should be considered.