Ó
2000 Martin Dunitz Ltd
International Journal of Psychiatry in Clinical Practice 2000 Volume 4 Pages 135 ± 138
135
A survey of lithium monitoring and prescribing patterns JANET A BUTLER AND DAVID TAYLOR
Int J Psych Clin Pract Downloaded from informahealthcare.com by CDL-UC Santa Cruz on 12/04/14 For personal use only.
Maudsley Hospital, London, UK
Correspondence Address Dr Janet Butler, University Mental Health Group, Royal South Hants Hospital, Brintons Terrace, Southampton SO14 0YG, UK Tel: +44 (0) 2380 825544 Fax: +44 (0) 2380 234243 E-mail: [email protected]
Received 7 April 1999; revised 1 September 1999; accepted for publication 22 September 1999
In the United Kingdom, guidelines for the monitoring of lithium are published in the British National Formulary. METHOD: Lithium monitoring and prescribing were retrospectively reviewed over a 6-year period in current patients of one General Adult Psychiatry team in Greater London. There were no instances of adherence to BNF guidelines at the start of treatment. RESULTS: In outpatients, 44% of subsequent monitoring intervals were longer than recommende d and 10% of serum levels were above the recommende d range of serum concentrations. Analysis of prescribing patterns by a senior pharmacist estimated 34% of the dose changes to have been inappropriat e according to the trend of serum lithium levels. CONCLUSION : These results imply poor monitoring of patients on lithium, especially at the start of treatment. Training needs should be addressed. During lithium therapy, dose changes should be made with reference to previous serum levels. (Int J Psych Clin Pract 2000; 4: 135 ± 138) INTRODUCTION:
Keywords lithium
INTRODUCTION
L
ithium is a drug used widely in psychiatry. Careful monitoring is needed because of its narrow therapeutic index, with toxicity manifesting as renal and neurologica l complications and leading to a risk of death. Guidelines for its use have varied over the years but in the United Kingdom the current British National Formulary (BNF)1 recommends monitoring serum lithium concentrations weekly until the dosage has been constant for 4 weeks, and every 3 months thereafter, aiming for plasma concentrations between 0.4 mmol/l and 1.0 mmol/l. Evidence suggests that during treatment these guidelines are not adhered to,2 ,3 and responses to measured serum concentrations may be inappropriat e.2 ,4 Some studies indicated a risk of rebound mania upon cessation of lithium therapy, which led Goodwin to advocate treatment for a minimum of 3 years for lithium’s prophylactic benefit to outweigh a possible increase d risk of relapse when lithium is stopped.5 In contrast to previous studies, this study aimed to determine monitoring patterns for serum lithium concentrations at the start of therapy and after a break in treatment, as well as at stable dosage, in one clinical team. Attention was paid to difference s between grades of staff and between inpatients and outpatients.
drug monitoring
METHOD The study population was the current caseload of one General Adult Psychiatry team based in a suburban area of London serving a population of 47 000. The medical notes of the study population were requested, for hand-searc hing of filed results, drug charts, corresponden ce and clinical notes, to find all serum lithium concentrations and correspondi ng lithium doses during the period January 1990 to December 1996. No values were excluded. The biochemistry laboratory record for the team was checked from January 1995 to December 1996 to estimate missing data. A record was made if the sample had been requested whilst the patient was hospitalized . If the sample was taken in the outpatient clinic, the grade of doctor who saw the patient on that visit was recorded. Patients usually saw a doctor of the same grade of seniority on each visit. In the few instances where a change in the grade of doctor occurred, the measured lithium levels for that patient were split, and recorded with the grade of doctor seen when the level was taken. For values recorded in the outpatient clinic, the time between measurement s was calculated separately for standard outpatient requests and for the first request taken after an admission. The time of the first request after initiation of therapy was recorded, and
Int J Psych Clin Pract Downloaded from informahealthcare.com by CDL-UC Santa Cruz on 12/04/14 For personal use only.
136
JA Butler and D Taylor
thereafter the time between the recorded levels was calculated, to judge the frequency of requests. Dosing regimes for each patient were reviewed by an experience d clinical pharmacist (DT) to establish their appropriaten ess according to the serum lithium values in the notes. Inappropriat e dose changes included situations where the dose appeared to be changed because of a single measured level that did not fit the pattern of previous results (where a repeat level was indicated before a dosage change), or where the new dose appeared too large or small for the desired change in concentration. Neither the pathology request forms nor the results sheets in the hospital concerned provide a record of the timing of the sample in relation to the last dose of lithium, and therefore all levels were assumed to have been taken 12 h after the dose.
RESULTS SUBJECTS There were 226 patients on the current caseload. Thirteen sets of casenotes could not be located, leaving 213 available for the study. Lithium was given to 55 patients during the study period. The most common diagnoses were bipolar affective disorder (21) and recurrent depression (28), but others included schizoaffect ive disorder (4), drug-induce d psychosis (1) and cyclothymia (1). There were records of 345 serum concentrations from outpatients and 105 from inpatients. The separate search of biochemistry records located nine extra values to include in the 2-year period where 135 had already been found in the notes. This would suggest 18 missing values for the remaining 4 years of the study.
INITIATION OF LITHIUM THERAPY There were no records of serial concentrations to ensure a stable value upon commencement of lithium therapy or after any dosage change. The mean time to the first lithium level recorded was 10 days for inpatients and 2.3
months (range 5 days to 12 months; median 1 month) for outpatients. For outpatients, this rose to 5.5 months after recommencement of therapy following a break in treatment (range 7 days to 18 months; median 6 months).
MONITORING OF LITHIUM IN OUTPATIENTS The overall mean time between standard records of outpatient lithium levels was 4.2 months, but this varied from 2.1 to 6.8 months for different grades of doctor (Table 1). The overall median time between standard outpatient levels was 3 months. For the whole sample, monitoring intervals ranged from 1 week to 48 months; 44% of the monitoring intervals unrelated to admission (121/273) were over 3 months and 7% (9/121) of these were 1 year or longer. Apart from one level mentioned in a letter referring the patient back to the psychiatric team, there was no mention in either the clinical notes or corresponden ce of levels taken by General Practitioners , and therefore it was assumed that the psychiatrist s were unaware of levels not taken by themselves.
DURATION OF TREATMENT Four patients commenced lithium within 6 months of the end of the study. Eleven patients had less than 6 months’ therapy for other reasons (eight due to recognized noncompliance and three because the doctor had stopped therapy after the patient had complained about sideeffects).
EPISODES OF TREATMENT Fifteen episodes of treatment (involvin g 11 patients) lasted less than 6 months (Table 2), either due to non-adheren ce (11 episodes), or to intoleranc e of side-effect s leading the doctor to stop treatment (four episodes). Eighteen episodes of treatment (involvin g 12 patients) were the second or third attempt at treatment with lithium after nonadherence.
Table 1 Outpatient monitoring of stable lithium treatment Grade of doctor seen in outpatients clinic
No. of monitoring intervals unrelated to admissions
Mean time between levels unrelated to admissions (months)
Mean time to first level recorded following inpatient discharge (months)
Consultant Clinical assistant Senior registrar Senior house officer
64 87 23 99
6.8 3.7 2.1 3.5
3.3 1.0 1.8 2.3
All staff
273
4.2
2.4
Lithium monitoring and prescribing
137
Table 2 Levels outside the recommended range
Int J Psych Clin Pract Downloaded from informahealthcare.com by CDL-UC Santa Cruz on 12/04/14 For personal use only.
Lithium level measured by
Levels under 0.4 mmol/l No. %
Levels over 1.0 mmol/l No. %
Levels over 1.2 mmol/l No. %
Mean time before last level taken, for levels over 1.2 mmol/l (months)
Consultant Clinical assistant Senior registrar Senior house officer
11 10 2 8
12 10 7 6
6 8 4 13
7 8 14 10
2 3 0 6
3 3 0 5
4 0.3 N/A 2.8
All outpatient levels
31
9
31
9
11
4
2.1
Inpatient sample
5
5
13
12
6
6
3
All inpatient levels
36
8
44
10
17
4
1.5
LEVELS OUTSIDE THE RECOMMENDED RANGE Eighteen percent (62/345) of outpatient measurement s and 17% (18/105) of inpatient measurement s fell outside the recommended range of 0.4 mmol/l to 1.0 mmol/l (Table 2). Three inpatient levels over 1.2 mmol/l were found on admission, and for two of these, their level had not been measured in the preceding 6 months. One serum concentration was over 1.5 mmol/l; the preceding measurement had been taken 1 month earlier.
DOSE CHANGES There were 73 dose changes, of which 25 (34%) were judged to be inappropriat e according to serum values. There were several occasions when variation in levels suggested non-complian ce, but prescribin g continued. There were several instances of failure to notice a pattern of rising levels before clinical toxicity developed. In one case, a level of 1.43 mmol/l in an inpatient resulted in cessation of therapy for 3 days and then resumption of the previous dose, leading to another episode of toxicity before the lithium dose was reduced.
DISCUSSION We found that standards of lithium monitoring fell below that recommended in BNF guidelines . This was most marked at the commencement of therapy, where there was no instance of adherence to guidelines . Initial lithium levels should be measured, since there is considerabl e interpersonal variabilit y in lithium metabolism: 4 ± 7 days is needed to achieve a steady state, so first levels need to be taken at this time. However, despite non-complian ce with BNF guidelines, we found no documented instances of clinical toxicity when patients started lithium. If this finding were to be
replicated in future studies, taking lithium levels 12 hours after the last dose, it may suggest a need to re-evaluat e the BNF guidelines . It is not known whether the infrequent initial monitoring led to levels which produced increased side-effect s despite lack of biochemica l toxicity. Careful monitoring of lithium is needed even when a stable dose is achieved. Within the same person, lithium levels can change due to drug interactions, changes in sodium balance, dehydration and renal impairment . It is possible that long-term effects of lithium on the kidney and thyroid are dose-related. In this study many outpatient monitoring intervals were longer than recommende d, with a substantial minority being more than four times as long. The longest monitoring intervals before finding a level over 1.2 mmol/l occurred for two samples taken on admission, which suggests that poor monitoring may have contributed to toxicity necessitating admission. A recent survey noted that many general practitioners would appreciate reminders that blood tests for lithium levels were due.6 Our present study suggests that such a system may also be beneficial to psychiatrist s. The high proportion of inappropriat e dose changes according to serum lithium values is worrying, particularl y where failure to adjust the dose appropriately led to clinical toxicity. These findings indicate that further education of doctors in clinical pharmacolo gy may reduce patient morbidity and hospital admissions . A `results sheet’ recording a series of previous results for that patient may be helpful. Some of the dose changes in this study may have been inappropriat e because the doctors assumed, or knew, that the sample had been taken more or less than 12 hours from the preceding dose. Ideally this information would be included on the request and results forms. Nevertheless , interpretatio n of samples taken at different times following a dose is extremely complex. Long monitoring intervals and high lithium levels were not always related. The consultants’ records showed the
Int J Psych Clin Pract Downloaded from informahealthcare.com by CDL-UC Santa Cruz on 12/04/14 For personal use only.
138
JA Butler and D Taylor
longest monitoring intervals but the fewest high levels. It may be that other factors, such as tremor or other sideeffects, were used to monitor lithium therapy in addition to serum lithium concentrations . There should be further work to determine the best parameters to monitor lithium in routine clinical practice. Short episodes of treatment may be clinically indicated (eg: for simple depression) but should be viewed with some caution, following Goodwin’s review of the risk : benefit ratio of short-term treatment.5 However this review was published during the period of our study, so could not have been seen by doctors prescribin g lithium earlier in the period. Perhaps more commonly, short-term treatment may indicate poor adherence to medication. The short treatment episodes and repeatedly low results in particular patients support this hypothesis. Doctors should be alert to nonadherence. They should raise the matter in a nonconfrontationa l way with all patients who display erratic levels or repeatedly low levels. Increasing the frequency of visits at the start of treatment may give the patient an opportunity to express their concerns regarding medication. If side-effect s are a particular problem then an alternative mood stabilizer more acceptable to these patients could be considered.
Overall, we found lithium monitoring to be poor. The complete lack of records of lithium levels 1 week after starting treatment, both in inpatients and outpatients, is particularly worrying. During treatment there was more regular monitoring, although great variation was found, with 7% of levels being more than a year apart. Noncompliance contributed to most of the episodes of treatment under 6 months’ duration. According to serum lithium levels, 34% of dose changes appeared inappropriate.
KEY POINTS
· · ·
Patients need checks of serum lithium levels when starting treatment Dose changes should be made with referenc e to a series of preceding serum lithium values Further research should clarify whether nonbiochemical indicators are useful in preventing lithium toxicity
REFERENCES 1. British Medical Association & Royal Pharmaceutical Society (1997) British National Formulary 33: 170 ± 1. 2. Kehoe RF, Mandler AJ (1992) Lithium treatment: prescribing and monitoring habits in hospital and general practice. Br Med J 304: 552 ± 4. 3. Ryman A (1997) Lithium monitoring in hospital and general practice. Psychiatr Bull 21: 570 ± 2. 4. Myers DH, Hallworth MJ (1996) An investigation into lithium monitoring. Psychiatr Bull 20: 333 ± 4.
5. Goodwin GM (1994) Recurrence of mania after lithium withdrawal. Implications for the use of lithium in the treatment of bipolar affective disorder. Br J Psychiatry 164: 149 ± 52. 6. Kotak A, Arnold AE, Frost P (1999) Monitoring lithium treatment: evaluation of current management. Psychiatr Bull 23: 83 ± 6.
2000 Martin Dunitz Ltd
International Journal of Psychiatry in Clinical Practice 2000 Volume 4 Pages 135 ± 138
135
A survey of lithium monitoring and prescribing patterns JANET A BUTLER AND DAVID TAYLOR
Int J Psych Clin Pract Downloaded from informahealthcare.com by CDL-UC Santa Cruz on 12/04/14 For personal use only.
Maudsley Hospital, London, UK
Correspondence Address Dr Janet Butler, University Mental Health Group, Royal South Hants Hospital, Brintons Terrace, Southampton SO14 0YG, UK Tel: +44 (0) 2380 825544 Fax: +44 (0) 2380 234243 E-mail: [email protected]
Received 7 April 1999; revised 1 September 1999; accepted for publication 22 September 1999
In the United Kingdom, guidelines for the monitoring of lithium are published in the British National Formulary. METHOD: Lithium monitoring and prescribing were retrospectively reviewed over a 6-year period in current patients of one General Adult Psychiatry team in Greater London. There were no instances of adherence to BNF guidelines at the start of treatment. RESULTS: In outpatients, 44% of subsequent monitoring intervals were longer than recommende d and 10% of serum levels were above the recommende d range of serum concentrations. Analysis of prescribing patterns by a senior pharmacist estimated 34% of the dose changes to have been inappropriat e according to the trend of serum lithium levels. CONCLUSION : These results imply poor monitoring of patients on lithium, especially at the start of treatment. Training needs should be addressed. During lithium therapy, dose changes should be made with reference to previous serum levels. (Int J Psych Clin Pract 2000; 4: 135 ± 138) INTRODUCTION:
Keywords lithium
INTRODUCTION
L
ithium is a drug used widely in psychiatry. Careful monitoring is needed because of its narrow therapeutic index, with toxicity manifesting as renal and neurologica l complications and leading to a risk of death. Guidelines for its use have varied over the years but in the United Kingdom the current British National Formulary (BNF)1 recommends monitoring serum lithium concentrations weekly until the dosage has been constant for 4 weeks, and every 3 months thereafter, aiming for plasma concentrations between 0.4 mmol/l and 1.0 mmol/l. Evidence suggests that during treatment these guidelines are not adhered to,2 ,3 and responses to measured serum concentrations may be inappropriat e.2 ,4 Some studies indicated a risk of rebound mania upon cessation of lithium therapy, which led Goodwin to advocate treatment for a minimum of 3 years for lithium’s prophylactic benefit to outweigh a possible increase d risk of relapse when lithium is stopped.5 In contrast to previous studies, this study aimed to determine monitoring patterns for serum lithium concentrations at the start of therapy and after a break in treatment, as well as at stable dosage, in one clinical team. Attention was paid to difference s between grades of staff and between inpatients and outpatients.
drug monitoring
METHOD The study population was the current caseload of one General Adult Psychiatry team based in a suburban area of London serving a population of 47 000. The medical notes of the study population were requested, for hand-searc hing of filed results, drug charts, corresponden ce and clinical notes, to find all serum lithium concentrations and correspondi ng lithium doses during the period January 1990 to December 1996. No values were excluded. The biochemistry laboratory record for the team was checked from January 1995 to December 1996 to estimate missing data. A record was made if the sample had been requested whilst the patient was hospitalized . If the sample was taken in the outpatient clinic, the grade of doctor who saw the patient on that visit was recorded. Patients usually saw a doctor of the same grade of seniority on each visit. In the few instances where a change in the grade of doctor occurred, the measured lithium levels for that patient were split, and recorded with the grade of doctor seen when the level was taken. For values recorded in the outpatient clinic, the time between measurement s was calculated separately for standard outpatient requests and for the first request taken after an admission. The time of the first request after initiation of therapy was recorded, and
Int J Psych Clin Pract Downloaded from informahealthcare.com by CDL-UC Santa Cruz on 12/04/14 For personal use only.
136
JA Butler and D Taylor
thereafter the time between the recorded levels was calculated, to judge the frequency of requests. Dosing regimes for each patient were reviewed by an experience d clinical pharmacist (DT) to establish their appropriaten ess according to the serum lithium values in the notes. Inappropriat e dose changes included situations where the dose appeared to be changed because of a single measured level that did not fit the pattern of previous results (where a repeat level was indicated before a dosage change), or where the new dose appeared too large or small for the desired change in concentration. Neither the pathology request forms nor the results sheets in the hospital concerned provide a record of the timing of the sample in relation to the last dose of lithium, and therefore all levels were assumed to have been taken 12 h after the dose.
RESULTS SUBJECTS There were 226 patients on the current caseload. Thirteen sets of casenotes could not be located, leaving 213 available for the study. Lithium was given to 55 patients during the study period. The most common diagnoses were bipolar affective disorder (21) and recurrent depression (28), but others included schizoaffect ive disorder (4), drug-induce d psychosis (1) and cyclothymia (1). There were records of 345 serum concentrations from outpatients and 105 from inpatients. The separate search of biochemistry records located nine extra values to include in the 2-year period where 135 had already been found in the notes. This would suggest 18 missing values for the remaining 4 years of the study.
INITIATION OF LITHIUM THERAPY There were no records of serial concentrations to ensure a stable value upon commencement of lithium therapy or after any dosage change. The mean time to the first lithium level recorded was 10 days for inpatients and 2.3
months (range 5 days to 12 months; median 1 month) for outpatients. For outpatients, this rose to 5.5 months after recommencement of therapy following a break in treatment (range 7 days to 18 months; median 6 months).
MONITORING OF LITHIUM IN OUTPATIENTS The overall mean time between standard records of outpatient lithium levels was 4.2 months, but this varied from 2.1 to 6.8 months for different grades of doctor (Table 1). The overall median time between standard outpatient levels was 3 months. For the whole sample, monitoring intervals ranged from 1 week to 48 months; 44% of the monitoring intervals unrelated to admission (121/273) were over 3 months and 7% (9/121) of these were 1 year or longer. Apart from one level mentioned in a letter referring the patient back to the psychiatric team, there was no mention in either the clinical notes or corresponden ce of levels taken by General Practitioners , and therefore it was assumed that the psychiatrist s were unaware of levels not taken by themselves.
DURATION OF TREATMENT Four patients commenced lithium within 6 months of the end of the study. Eleven patients had less than 6 months’ therapy for other reasons (eight due to recognized noncompliance and three because the doctor had stopped therapy after the patient had complained about sideeffects).
EPISODES OF TREATMENT Fifteen episodes of treatment (involvin g 11 patients) lasted less than 6 months (Table 2), either due to non-adheren ce (11 episodes), or to intoleranc e of side-effect s leading the doctor to stop treatment (four episodes). Eighteen episodes of treatment (involvin g 12 patients) were the second or third attempt at treatment with lithium after nonadherence.
Table 1 Outpatient monitoring of stable lithium treatment Grade of doctor seen in outpatients clinic
No. of monitoring intervals unrelated to admissions
Mean time between levels unrelated to admissions (months)
Mean time to first level recorded following inpatient discharge (months)
Consultant Clinical assistant Senior registrar Senior house officer
64 87 23 99
6.8 3.7 2.1 3.5
3.3 1.0 1.8 2.3
All staff
273
4.2
2.4
Lithium monitoring and prescribing
137
Table 2 Levels outside the recommended range
Int J Psych Clin Pract Downloaded from informahealthcare.com by CDL-UC Santa Cruz on 12/04/14 For personal use only.
Lithium level measured by
Levels under 0.4 mmol/l No. %
Levels over 1.0 mmol/l No. %
Levels over 1.2 mmol/l No. %
Mean time before last level taken, for levels over 1.2 mmol/l (months)
Consultant Clinical assistant Senior registrar Senior house officer
11 10 2 8
12 10 7 6
6 8 4 13
7 8 14 10
2 3 0 6
3 3 0 5
4 0.3 N/A 2.8
All outpatient levels
31
9
31
9
11
4
2.1
Inpatient sample
5
5
13
12
6
6
3
All inpatient levels
36
8
44
10
17
4
1.5
LEVELS OUTSIDE THE RECOMMENDED RANGE Eighteen percent (62/345) of outpatient measurement s and 17% (18/105) of inpatient measurement s fell outside the recommended range of 0.4 mmol/l to 1.0 mmol/l (Table 2). Three inpatient levels over 1.2 mmol/l were found on admission, and for two of these, their level had not been measured in the preceding 6 months. One serum concentration was over 1.5 mmol/l; the preceding measurement had been taken 1 month earlier.
DOSE CHANGES There were 73 dose changes, of which 25 (34%) were judged to be inappropriat e according to serum values. There were several occasions when variation in levels suggested non-complian ce, but prescribin g continued. There were several instances of failure to notice a pattern of rising levels before clinical toxicity developed. In one case, a level of 1.43 mmol/l in an inpatient resulted in cessation of therapy for 3 days and then resumption of the previous dose, leading to another episode of toxicity before the lithium dose was reduced.
DISCUSSION We found that standards of lithium monitoring fell below that recommended in BNF guidelines . This was most marked at the commencement of therapy, where there was no instance of adherence to guidelines . Initial lithium levels should be measured, since there is considerabl e interpersonal variabilit y in lithium metabolism: 4 ± 7 days is needed to achieve a steady state, so first levels need to be taken at this time. However, despite non-complian ce with BNF guidelines, we found no documented instances of clinical toxicity when patients started lithium. If this finding were to be
replicated in future studies, taking lithium levels 12 hours after the last dose, it may suggest a need to re-evaluat e the BNF guidelines . It is not known whether the infrequent initial monitoring led to levels which produced increased side-effect s despite lack of biochemica l toxicity. Careful monitoring of lithium is needed even when a stable dose is achieved. Within the same person, lithium levels can change due to drug interactions, changes in sodium balance, dehydration and renal impairment . It is possible that long-term effects of lithium on the kidney and thyroid are dose-related. In this study many outpatient monitoring intervals were longer than recommende d, with a substantial minority being more than four times as long. The longest monitoring intervals before finding a level over 1.2 mmol/l occurred for two samples taken on admission, which suggests that poor monitoring may have contributed to toxicity necessitating admission. A recent survey noted that many general practitioners would appreciate reminders that blood tests for lithium levels were due.6 Our present study suggests that such a system may also be beneficial to psychiatrist s. The high proportion of inappropriat e dose changes according to serum lithium values is worrying, particularl y where failure to adjust the dose appropriately led to clinical toxicity. These findings indicate that further education of doctors in clinical pharmacolo gy may reduce patient morbidity and hospital admissions . A `results sheet’ recording a series of previous results for that patient may be helpful. Some of the dose changes in this study may have been inappropriat e because the doctors assumed, or knew, that the sample had been taken more or less than 12 hours from the preceding dose. Ideally this information would be included on the request and results forms. Nevertheless , interpretatio n of samples taken at different times following a dose is extremely complex. Long monitoring intervals and high lithium levels were not always related. The consultants’ records showed the
Int J Psych Clin Pract Downloaded from informahealthcare.com by CDL-UC Santa Cruz on 12/04/14 For personal use only.
138
JA Butler and D Taylor
longest monitoring intervals but the fewest high levels. It may be that other factors, such as tremor or other sideeffects, were used to monitor lithium therapy in addition to serum lithium concentrations . There should be further work to determine the best parameters to monitor lithium in routine clinical practice. Short episodes of treatment may be clinically indicated (eg: for simple depression) but should be viewed with some caution, following Goodwin’s review of the risk : benefit ratio of short-term treatment.5 However this review was published during the period of our study, so could not have been seen by doctors prescribin g lithium earlier in the period. Perhaps more commonly, short-term treatment may indicate poor adherence to medication. The short treatment episodes and repeatedly low results in particular patients support this hypothesis. Doctors should be alert to nonadherence. They should raise the matter in a nonconfrontationa l way with all patients who display erratic levels or repeatedly low levels. Increasing the frequency of visits at the start of treatment may give the patient an opportunity to express their concerns regarding medication. If side-effect s are a particular problem then an alternative mood stabilizer more acceptable to these patients could be considered.
Overall, we found lithium monitoring to be poor. The complete lack of records of lithium levels 1 week after starting treatment, both in inpatients and outpatients, is particularly worrying. During treatment there was more regular monitoring, although great variation was found, with 7% of levels being more than a year apart. Noncompliance contributed to most of the episodes of treatment under 6 months’ duration. According to serum lithium levels, 34% of dose changes appeared inappropriate.
KEY POINTS
· · ·
Patients need checks of serum lithium levels when starting treatment Dose changes should be made with referenc e to a series of preceding serum lithium values Further research should clarify whether nonbiochemical indicators are useful in preventing lithium toxicity
REFERENCES 1. British Medical Association & Royal Pharmaceutical Society (1997) British National Formulary 33: 170 ± 1. 2. Kehoe RF, Mandler AJ (1992) Lithium treatment: prescribing and monitoring habits in hospital and general practice. Br Med J 304: 552 ± 4. 3. Ryman A (1997) Lithium monitoring in hospital and general practice. Psychiatr Bull 21: 570 ± 2. 4. Myers DH, Hallworth MJ (1996) An investigation into lithium monitoring. Psychiatr Bull 20: 333 ± 4.
5. Goodwin GM (1994) Recurrence of mania after lithium withdrawal. Implications for the use of lithium in the treatment of bipolar affective disorder. Br J Psychiatry 164: 149 ± 52. 6. Kotak A, Arnold AE, Frost P (1999) Monitoring lithium treatment: evaluation of current management. Psychiatr Bull 23: 83 ± 6.
