Can we check serum lithium levels less often without compromising patient safety?

Heald, Adrian H.; Holland, David; Stedman, Michael; Davies, Mark; Duff, Chris J.; Parfitt, Ceri; Green, Lewis; Scargill, Jonathan; Taylor, David; Fryer, Anthony A.

Abstract

BACKGROUND: Lithium is viewed as the first-line long-term treatment for prevention of relapse in people with bipolar disorder.

AIMS: This study examined factors associated with the likelihood of maintaining serum lithium levels within the recommended range and explored whether the monitoring interval could be extended in some cases.

METHOD: We included 46 555 lithium rest requests in 3371 individuals over 7 years from three UK centres. Using lithium results in four categories (<0.4 mmol/L; 0.40-0.79 mmol/L; 0.80-0.99 mmol/L; =1.0 mmol/L), we determined the proportion of instances where lithium results remained stable or switched category on subsequent testing, considering the effects of age, duration of lithium therapy and testing history.

RESULTS: For tests within the recommended range (0.40-0.99 mmol/L categories), 84.5% of subsequent tests remained within this range. Overall, 3 monthly testing was associated with 90% of lithium results remaining within range, compared with 85% at 6 monthly intervals. In cases where the lithium level in the previous 12 months was on target (0.40-0.79 mmol/L; British National Formulary/National Institute for Health and Care Excellence criteria), 90% remained within the target range at 6 months. Neither age nor duration of lithium therapy had any significant effect on lithium level stability. Levels within the 0.80-0.99 mmol/L category were linked to a higher probability of moving to the =1.0 mmol/L category (10%) compared with those in the 0.4-0.79 mmol/L group (2%), irrespective of testing frequency.

CONCLUSION: We propose that for those who achieve 12 months of lithium tests within the 0.40-0.79 mmol/L range, the interval between tests could increase to 6 months, irrespective of age. Where lithium levels are 0.80-0.99 mmol/L, the test interval should remain at 3 months. This could reduce lithium test numbers by 15% and costs by ~$0.4 m p.a.

Citation

Heald, A. H., Holland, D., Stedman, M., Davies, M., Duff, C. J., Parfitt, C., Green, L., Scargill, J., Taylor, D., & Fryer, A. A. (2021). Can we check serum lithium levels less often without compromising patient safety?. BJPsych Open, e18 - ?. https://doi.org/10.1192/bjo.2021.1027

• Journal Article Type: Article
• Acceptance Date: Sep 13, 2021
• Publication Date: Dec 17, 2021
• Journal: BJPsych Open
• Print ISSN: 2056-4724
• Electronic ISSN: 2056-4724
• Publisher: Cambridge University Press
• Peer Reviewed: Peer Reviewed
• Pages: e18 - ?
• DOI: https://doi.org/10.1192/bjo.2021.1027
• Keywords: Lithium; level; testing; interval; safety
• Public URL: https://keele-repository.worktribe.com/output/422209
• Publisher URL: https://www.cambridge.org/core/journals/bjpsych-open/article/can-we-check-serum-lithium-levels-less-often-without-compromising-patient-safety/531E24974966619C8EBDD746831D85D8