The main findings were that documented evidence that baseline tests of renal and thyroid function had been conducted was found for just over four-fifths of patients recently commenced on lithium therapy, and for those patients receiving lithium treatment for a year or more, the frequency of monitoring of serum lithium and renal and thyroid function met the standards set by NICE in less than a third to just over a half of patients, depending on the measure.
Previous published audits of the quality of lithium monitoring have tended to be relatively small and locality specific. They also pre-date the NICE bipolar guideline, and used older audit standards from the British National Formulary (see table 2). These factors render it difficult to directly compare our findings with those of the audits conducted earlier in this area, but there is little to suggest a trend for improvement over time.
Why is recommended monitoring not carried out?
Possible explanations for suboptimal monitoring may implicate procedural, patient and/or practitioner variables.
With respect to procedural factors, previous audits have reported incomplete local implementation of monitoring guidelines , poor communication of test results to clinical teams, lack of communication between primary and secondary care  and a lack of dedicated monitoring services and central registers that generate reminders that tests are due [10, 13]. Our study corroborates these findings by revealing variable adoption of monitoring guidelines and use of shared care protocols by mental health Trusts, with few clinicians having electronic access to test results. In addition, few Trusts operate designated lithium clinics and only one reported having a local database specifically for lithium that produced automatic prompts when biochemical tests were due.
Communication could be improved through the development of local registers of lithium-treated patients (with systems for review and recall), and local needs assessment (complemented by audit, training and the use of appropriate guidelines) [12–14]. Bringing primary and secondary care teams together to agree on a model of shared care suited to local needs may also be important .
Previous studies have identified a number of patient-related factors that may influence monitoring rates. These include variation in the willingness of patients to have blood tests [15, 16], and either receiving inadequate information about lithium treatment and the need for regular blood tests or not assimilating the information given [8, 17, 18]. Our findings provide support for the view that many patients are not provided with basic information about their lithium treatment.
Patient demographics may plausibly influence the quality of monitoring of psychotropic medication , but to what extent this would be driven by variable engagement with healthcare by patients and the behaviour of clinicians is uncertain. Our study did not identify any contribution from gender or ethnicity, but found that monitoring practice for patients cared for by older peoples services was generally better than that provided by general adult services. This may reflect that clinicians in elderly services have an increased awareness of lithium monitoring requirements for their patients, who are particularly vulnerable to renal side-effects, and in whom the background prevalence of thyroid problems is higher than in younger adults. Our audit also revealed slightly superior monitoring of body weight for patients with a diagnosis of a schizophrenia spectrum disorder, which may indicate increased clinician awareness of risk factors for weight gain in such patients [20, 21].
With respect to practitioner-related factors, several studies report superior standards of lithium monitoring for patients under the care of a psychiatrist [9, 11, 22] while others report no difference from the quality of monitoring undertaken by general practitioners [23, 24]. Some audits also report superior monitoring for those patients in nurse-led, designated lithium clinics  or under pharmacist supervision . It has been suggested that the large variation in the degree of knowledge about lithium and its monitoring requirements amongst individual professionals may account for these inconsistent findings . There may also be variation between clinicians in the acceptance of the need for monitoring at the frequency recommended by NICE.
The use of incentivised care in improving monitoring practice
Mental health Trusts within the UK are required to implement NICE guidelines and progress with this is monitored by the Care Quality Commission (CQC). In contrast, there are no sanctions for General Practitioners who fail to meet QOF targets, rather a positive benefit in the form of payment when these targets are met.
In our sample, the primary care QOF targets with respect to monitoring of serum lithium was met in over two-thirds of cases, and the target with respect to renal and thyroid function in just over four fifths. The NHS Information Centre (QOF statistics for England, 2008/9) lists these targets as having been met for 91% and 97.4% of patients respectively within primary care in 2008/9 . As it is likely that the care of the majority of patients who are prescribed lithium is shared between primary and secondary care, less apparent monitoring in our secondary care sample may partly reflect communication issues between these sectors.
Proponents of a system like QOF argue that it can improve the implementation of evidence-based interventions  in primary care and constitutes an important quality improvement tool. However, critics have expressed concerns that QOF targets are too low with poor discriminatory value , and that incentivised care will never be an adequate substitute for professional judgment . Our finding that the proportion of patients monitored in line with QOF targets was higher in primary than secondary care supports the view that the QOF system is a viable quality improvement tool. There is however, a need for more objective and transparent setting of QOF targets and increasing convergence between these and NICE standards.
Study strengths and limitations
A possible limitation of our study is a bias in the selection of patient samples for audit by each participating Trust. Such bias is unlikely to be unidirectional in that clinical teams that consider they are performing well in relation to meeting the relevant practice standards may choose to participate, whereas Trusts may choose to submit data for teams that they suspect are performing less well. The net result of competing sources of bias is unknown. Poor documentation standards or quality of case note review in this audit could also account for observed failures in monitoring practice.
A strength of the work is that our audit sample is larger than those of all previously published studies combined and is drawn from across the UK. Trusts that participated in the audit are representative of all NHS mental health Trusts  and so it is likely that our findings are generalisable to practice in other Trusts and representative of current clinical practice in the UK.