Relationship Between Lithium Dose, Serum Concentration and Duration of Lithium Therapy with Cutaneous Side-effects in Bipolar Affective Disorder Patients

Abstract

Introduction: Lithium has been used in the treatment of mood disorders for more than five decades. Despite a few studies focusing on the relationship between the dose of lithium, serum lithium levels, duration of therapy, and cutaneous side-effects, results remain inconclusive. Lithium is known to cause multiple cutaneous side-effects like acneiform eruptions, psoriasiform eruption, seborrheic dermatitis, and follicular keratitis. Aim: To evaluate the relationship between cutaneous side-effects of lithium with the serum lithium levels, dosage and duration of lithium therapy in bipolar affective disorder patients. Materials and Methods: An ambispective observational study conducted among 52 bipolar affective disorder patients on lithium therapy recruited by convenient sampling methods from both Inpatients and Outpatient Psychiatry Units of PSG Institute of medical sciences and research, Coimbatore, Tamil Nadu, India, June 2014 to August 2014. The patients with bipolar affective disorder who are either newly started on lithium or already on lithium therapy were included in the study. They were followedup to assess the effect of lithium dosage, duration of lithium and serum lithium level with skin lesions, once a month for six months and once in two months for one year. Kaplan-Meier survival analysis was done with varying lithium dosages and serum lithium levels. Association between the lithium dose and serum lithium levels with the cutaneous side-effects were calculated using the survival analysis with the p-value of <0.01. Results: Out of the total, 59.6 % of the participants were in the age group less than 40 years and 34.6 % were in the age group 40-60 years. There was almost equal distribution of males and females, 51.9% and 48.1%, respectively. Overall, 38.46% participants had cutaneous lesions. Various lithium dosage and serum lithium levels did not correlate statistically with skin reactions upto one year. Survival analysis at the end of 10 years revealed that participants with higher dosage and serum levels had higher prevalence of skin lesions (40% vs 4%: 47.1% vs 6.6% respectively, p-value <0.001). The cumulative proportion of skin lesions at the end of three, five, seven and 10 years for higher dose (>800 mg/day) was 38%, 46.9%, 52.2%, 59% and for higher lithium levels (>0.8 mEq/L) was 41%, 58.2%, 65.2%, 73.9%. Conclusion: The patients who were treated with lower dosage and who had lower serum lithium level had reduced risk for cutaneous lesions. Lithium continued to exert its mood stabilisation property even when the serum level was maintained less than 0.8 mEq/L. This resulted in better compliance