There is a lack of pharmacological trials studying drug response in Persistent Delusional Disorder (PDD) to guide clinical practice. Available reviews of retrospective data indicate good response to second-generation antipsychotics, but even such data from India is sparse.

We aimed to compare the response of acute PDD to risperidone and olanzapine in our retrospective review.

We conducted a retrospective chart review of patients diagnosed with PDD (ICD-10) from 2000 to 2014 (n = 455) at our Center. We selected the data of patients prescribed either olanzapine or risperidone for the purpose of this analysis. We extracted data about dose, drug compliance and response, adverse effects, number of follow-up visits and hospitalizations. The study was approved by the Institute Ethics Committee.

A total of 280/455 (61%) were prescribed risperidone and 86/455 (19%) olanzapine. The remaining (n = 89; 20%) had received other antipsychotics. The two groups were comparable in socio-demographic and clinical characteristics of PDD. Compliance was good and comparable in both groups (> 80%, P = 0.2). Response to treatment was comparable in both groups (85% partial response and > 52% good response, all P > 0.3). Olanzapine was effective at lower mean chlorpromazine equivalents than risperidone (240 vs. 391, P < 0.05).

Our study indicates a good response to both risperidone and olanzapine, if compliance to treatment can be ensured. In the absence of specific treatment guidelines for PDD, second-generation antipsychotics like risperidone and olanzapine offer good treatment options for this infrequently encountered and difficult to treat psychiatric disorder.

The authors have not supplied their declaration of competing interest.