Psychiatrists' perspectives on antipsychotic dose and the role of plasma concentration therapeutic drug monitoring.

BACKGROUND

Why psychiatrists choose a particular dose of antipsychotic for an individual patient with schizophrenia is unknown. This study aimed to investigate consultant psychiatrists' perspectives on the dose titration and their attitudes towards therapeutic drug monitoring (TDM) for antipsychotics.

METHOD

A cross-sectional quantitative questionnaire study of consultant psychiatrists based in London was conducted. A new questionnaire was developed, in part, based on the findings from focus groups. Themes included dose choice, titration, switching, and the pros and cons of TDM use.

RESULTS

For 105 consultant psychiatrists, choice of antipsychotic was most influenced by perceived side-effects/tolerance (63.8%). When choosing an optimum dose, most based this on their past clinical experience of patients presenting in a similar way (80.0%), perspectives on the equivalent doses of 2 antipsychotics (69.5%), or the individual patient's stated dose preference (61.9%). Factors thought to warrant a lower dose (eg, first episode psychosis) were consistent with a former study, and 59.0% of the clinicians believed it acceptable to switch antipsychotics ≥4 per year. The majority of clinicians currently routinely use TDM for clozapine (82.9%), and previous use of TDM for clozapine was found to predict likely future use of TDM with antipsychotics (χ = 5.51, P = 0.019). Furthermore, clinicians agreed that TDM could assist in minimizing the risk of dose-related side effects (77.1%). However, 32.4% did not agree that TDM would improve clinical outcomes. Overall, there was a positive attitude towards TDM for antipsychotics, and almost all clinicians (84.8%, 95% confidence interval, 77.9-91.7) would use it if widely available.

CONCLUSIONS

Current prescribing decisions regarding antipsychotic dose are mainly influenced by clinician intuition, previous experience, and patient preference. Although some expressed concerns regarding the evidence base, most clinicians reported that they would use TDM for antipsychotics if readily available.