Letter

In Reply: We appreciate Dr. Babbar's letter, which brings much needed attention to a serious safety concern—hospitalization for adverse drug reactions, which could result from treatment with multiple antipsychotic medications. We share his concern about this and other potential adverse consequences of a treatment strategy that lacks solid evidence for its efficacy and safety.

Dr. Babbar correctly notes that patients prescribed antipsychotic polypharmacy in our study were more likely to receive several other psychiatric medications, which could further increase their risks of adverse effects and subsequent hospitalizations. In addition, patients receiving polypharmacy were prescribed antipsychotic dosages that were the same as or higher than for those receiving monotherapy and had greater use of anti-Parkinson agents, which suggests that they were at risk of or were already experiencing side effects related to excess antipsychotic exposure. These findings lend further support to Dr. Babbar's hypothesis that rather than reflecting the severity of patients' psychotic symptoms (a potential indication for the use of polypharmacy), the higher rate of past-year psychiatric hospitalization was a result of the adverse effects of multiple medications.

The overall goal of our study was to describe patient characteristics and treatment patterns associated with long-term antipsychotic polypharmacy. Although the safety and effectiveness of antipsychotic polypharmacy are important and unresolved issues, evaluating the outcomes of this treatment strategy was beyond the scope of our cross-sectional investigation. Further, we were not able to determine the reasons for the hospitalizations in question, although we do know that they reflected admissions to psychiatric or addiction treatment units. It is also important to note that the psychiatric hospitalizations occurred in the year before the period during which we documented patients' antipsychotic and other psychotropic treatments. We have no information regarding the medications prescribed before these admissions. This led us to infer that the previous hospitalizations were indicators of the severity of psychiatric illness of patients receiving antipsychotic polypharmacy, a conclusion reached by others who have reported a similar association between polypharmacy and previous hospitalization ( 1 , 2 , 3 ).

Patients with refractory and disabling psychiatric symptoms (that may be reflected in increased use of inpatient psychiatric services) may be more likely to receive complicated psychotropic regimens that in turn induce adverse effects severe enough to result in hospitalization. We agree with Dr. Babbar that more research is needed to determine the extent to which this may be happening in routine clinical practice.