Do doctors agree on doses of antipsychotic medications?

BACKGROUND

The objective of this study was to investigate the concordance in attitudes of psychiatrists towards the doses of antipsychotics given to stable outpatients with schizophrenia and to examine the psychiatrists' estimates of equally potent doses of haloperidol and olanzapine.

METHODS

We asked all 22 doctors serving at the psychiatry department of Jönköping County Hospital if they considered the combined dose of antipsychotics for 20 individual patients to be 'low', 'medium' or 'high'. We also asked each doctor to state the dose of haloperidol that they considered to be clinically equivalent to 20 mg/day of olanzapine.

RESULTS

The inter-rater reliability (Krippendorff's alpha (α)) was 0.50, and the mean estimated dose haloperidol considered clinically equivalent to 20 mg/day of olanzapine was 4.45 mg/day.

CONCLUSIONS

The inter-rater reliability (Krippendorff's α) was low, suggesting lack of agreement. The dose of antipsychotics given to a patient might thus be more influenced by which doctor they meet than the severity of the disease. The respondents in this study considered a mean dose of 4.45 mg/day of haloperidol to be clinically equivalent to 20 mg/day of olanzapine. This is a considerably lower dose than was determined by an international consensus study of antipsychotic dosing, and more in line with the available PET studies measuring central dopamine receptor blockage of optimal clinical doses.