Abstract
Geoffrey Schrader, Senior Lecturer; Rima Al Atrash-Najar, Research Assistant, Department of Psychiatry, Adelaide University, Adelaide, Australia; Rohan Dhillon, Consultant Psychiatrist; Tarun Bastiampillai, Psychiatric Registrar North-West Adelaide Mental Health Service, Adelaide, Australia:
Therapeutic drug monitoring has been widely cited as a method to evaluate the adequacy and ensure the safety of treatment with mood stabilizing drugs. However, a number of reports have described less than adequate monitoring of these drugs [1, 2]. We set out to determine rates of monitoring of mood stabilizing drugs in patients with bipolar disorder in two community mental health clinics in metropolitan Adelaide and to determine whether severity of symptoms or presence of substance abuse, affected monitoring.
After obtaining informed consent, patients with bipolar disorder at the clinics were interviewed by a research assistant to determine symptom severity using the Brief Psychiatric Rating Scale [3] (BPRS), substance abuse using the substance abuse section of the Composite International Diagnostic Interview [4] and how frequently they visited the clinic. After approximately six months, adherence to established guidelines for the monitoring of mood stabilizing drugs was ascertained by checking case notes and by reviewing records of tests ordered at the two laboratories servicing the clinics.
Seventy-seven patients with a diagnosis of bipolar disorder were interviewed for the study. During a 12- month period, of patients prescribed lithium, 62% had no serum levels performed, only 11% had a thyroid function test performed and 17% had a creatinine level performed. Of patients prescribed sodium valproate, 38% had no serum levels performed, only 27% had a complete blood examination, and 17% had liver function tests performed. Of patients taking carbamazepine, 87% had no serum levels performed, only 38% had a complete blood examination, and 63% had liver function tests performed.
More younger than older patients were monitored, although this did not reach significance (χ 2 = 3.25, df = 1, p = 0.06). Mean BPRS scores (t = 0.09, df = 75, p = 0.9) did not differ significantly between those who had some form of monitoring and those who had none. Frequency of visits to the clinic did not differ significantly between those who were and who were not monitored (t = −0.17, df = 75, p = 0.8). There was no significant difference in rates of monitoring between patients who were or who were not dependent or abusing either alcohol or cannabis (χ 2 = 0.052, df = 1, p = 0.52).
We found even fewer patients received some sort of monitoring than previously reported in the US and UK. We similarly found that comorbid substance abuse or dependence and frequency of clinic visits, presumably markers of higher risk patients, were not associated with more frequent monitoring. An examination of the practice style, routine and custom at the two clinics may provide some insight into the low rates of monitoring we discovered. Both clinics had taken on substantially greater case loads following the closing of a mental hospital and the opening of a new mainstreamed psychiatric unit at a local general hospital some years prior to the study [5]. Services were provided on a generic basis, in the main by registrars rotating from the local hospital, with neither clinic having a mood disorders clinic. There were no specific case note forms to facilitate review of monitoring of drugs and neither clinic had access to computer software to aid monitoring. Interaction with local general practitioners was in the form of occasional written letters and there was little use of case conferencing or shared care plans. A survey of local general practitioners’ understanding of the need for monitoring of mood stabilizing drugs [6] indicated that a substantial number were unaware as to whether they or the mental health team should monitoring patients’ levels. In view of these findings, the clinics are considering the establishment of a mood disorders’ clinic, the introduction of alerting software and greater use of shared care arrangements with local general practitioners.
The study was supported by a grant from the Quality Use of Medicines Program, grant SG512.