Dr. Edith Sciberras, Dr. Lara Rapa, Dr. Claire Vassallo
Lithium is widely used for the treatment of bipolar disorder. Owing to its narrow therapeutic index and side-effect profile, regular monitoring of serum levels, renal and thyroid function has been recommended by all major guidelines on lithium use.
The aim of this study was to determine whether routine lithium monitoring practice during maintenance phase treatment at the local mental hospital reaches the standard set by the most recent NICE guidelines for assessment and management of bipolar disorder (NICE, 2014a).
Approval was sought from the Clinical Chairman of Psychiatry and Data Protection officer. Retrospective data were extracted from patient’s clinical file and iSOFT clinical manager (iCM). All patients on lithium maintenance phase treatment for dipolar disorder at the local Mental Hospital were included in the study. Blood test monitoring within the last 1 year were collected for each patient.
A sample of 42 patients were collected. 25 were males and 17 were females. 24% were aged 65 and above, 36% had interacting medications (NSAID, COX II inhibitor, thiazide or loop diuretic, ACE inhibitor or angiotensin II receptor antagonist ), 64% had co-morbid disease (hypertension, diabetes and/or any thyroid disorder) and 21% had kidney impairment (EGFR less than 60).
When assessing the last lithium level, 35.7% were within 0.4-0.8 mmol/L, 35.7% were within 0.8-1.0 mmol/L, 19% were below 0.4 mmol/l and 9.5% were above 1.0 mmol/L. For those patients who had >1 test result in the database, the recommendation of at least one test every 6 months was met 76.1% of cases for lithium level, 88% of cases for EGFR and renal function and 71.4% of cases for thyroid function. However, only 38% had a serum calcium level within the last 6 months. BMI and weight is recommended at least yearly, but only 14.2% met this recommendation within the last year.
Amongst this sample population, 28 patients met the NICE 2014 criteria for increased risk of toxicity (i.e. elderly, chronic co-morbidity and/or were co-prescribed at least one medication with a BNF-specified interaction with lithium) and have a recommended testing frequency for lithium levels of every 3 months. However, only 1 patient was observed to meet this criteria. 12 (42.8%) patients were observed to be monitored on a period of between 5-7 months, whilst 15 (53.5%) patients were observed on a period of greater than 7 months.
Lithium monitoring remains sub-optimal especially in patients considered as high risk patients according to NICE guidelines. The high number of test results below the therapeutic minimum is concerning, as it can play a pivotal role in treatment non-adherence and relapse. Clinical practice should actively be updated to meet the most recent evidence-based guidelines.
Introducing lithium therapy record sheets may help improving monitoring in Mount Carmel Hospital. This can also be extended to all patients on lithium therapy in the community.