Contents lists available at ScienceDirect Psychiatry Research journal homepage: www.elsevier.com/locate/psychres Risperidone versus olanzapine in the acute treatment of Persistent Delusional Disorder: A retrospective analysis Karishma Kulkarni a , Rashmi Arasappa a , Krishna Prasad M a , Amit Zutshi b , Prabhat K. Chand a , Pratima Murthy a , Mariamma Philip c , Kesavan Muralidharan a, ⁎ a Department of Psychiatry, National Institute of Mental Health and Neuro Sciences (INI), Bangalore-560029, Karnataka, India b Consultant Psychiatrist, Epworth Hospital, Camberwell, Victoria – 3124 & Honorary Consultant, Department of Psychiatry, Faculty of Medicine, Dentistry, and Health Sciences, The University of Melbourne, Australia c Department of Biostatistics, National Institute of Mental Health and Neuro Sciences (INI), Bangalore-560029, Karnataka, India ARTICLE INFO Keywords: Second generation antipsychotics Treatment response Logistic regression Predictors of response Chlorpromazine equivalents ABSTRACT There is a dearth of prospective trials studying treatment response in Persistent Delusional Disorder (PDD) to guide clinical practice. Available retrospective data indicate good response to second-generation antipsychotics (SGAs). We selected the data of patients prescribed either olanzapine or risperidone from a retrospective chart review of PDD (n=455) at our centre. We compared the two groups olanzapine (n =86) versus risperidone (n =280) on dose, drug adherence, response and adverse effects. The two groups were comparable on socio- demographic and clinical characteristics of PDD. There was no statistically significant difference between the two groups on adherence (> 80%) and response to treatment (> 52% good response). Olanzapine was effective at lower mean chlorpromazine equivalents than risperidone. Logistic regression analysis identified shorter mean duration of illness, good adherence and absence of substance dependence as predictors of good response to both drugs. Our study indicates that acute PDD responds well to treatment with both risperidone and olanzapine, provided adherence can be ensured. In the absence of specific treatment guidelines and randomized controlled trials for PDD, our analysis reaffirms the efficacy of SGAs. 1. Introduction Persistent delusional disorder (PDD) has a prevalence of 60/ 1,00,000 of the population according to most recent studies.(Kendler, 1982), (de Portugal et al., 2008) The low prevalence of the illness and its infrequent contact with mental health services has made it difficult to conduct double-blind, randomized controlled pharmacological trials for the acute treatment of PDD. Available evidence is in the form of single case studies, case series and retrospective reviews. In the absence of specific treatment guidelines for PDD, most clinicians extrapolate guidelines for the treatment of schizophrenia to the management of PDD (Smith and Buckley, 2006). It is reported that PDD has a good prognosis if treated adequately; and that all subtypes respond equally well to treatment. (Munro and Mok, 1995) Understandably, adherence to the treatment regimen determined outcomes. A review of newer antipsychotics reported a positive response to treatment in nearly 50% of the cases. A reduced reliance on pimozide, the erstwhile drug of choice for PDD (Munro and Mok, 1995), in favour of second-generation antipsychotics (SGAs) is also documented (Manschreck and Khan, 2006). A previous retrospective study from India reported that risperidone and pimozide produced the best response to treatment in that order and that only one-fourth of patients reported adverse effects (Grover et al., 2007). Freudenmann and Lepping (2008) found that among the SGAs, risperidone and olanzapine were the most commonly prescribed, with full or partial remission occurring in nearly 70% of patients and at doses lower than that for schizophrenia. (Freudenmann and Lepping, 2008) These findings were reflected in another case series which reported 67% response to risperidone/olanzapine with good compliance. This study also recorded the use of antidepressants in PDD with depressive symptoms. (Mews and Quante, 2013) With the availability of newer SGAs like quetiapine, aripiprazole and amisulpiride, whose efficacy has been field tested in schizophrenia and bipolar disorder, the options available to treat PDD have also increased. However, the absence of clinical data on the efficacy of these drugs in PDD has probably limited their use in favour of the older SGAs. There are case reports of PDD responding well to aripiprazole (infidelity) and quetiapine (erotomanic delusion) (Fear, 2013). http://dx.doi.org/10.1016/j.psychres.2017.02.066 Received 18 September 2016; Received in revised form 1 January 2017; Accepted 3 February 2017 ⁎ Correspondence to: Additional Professor of Psychiatry, National Institute of Mental Health and Neuro Sciences, Bangalore-560029, India. E-mail address: drmuralidk@gmail.com (K. Muralidharan). Psychiatry Research 253 (2017) 270–273 Available online 09 April 2017 0165-1781/ © 2017 Published by Elsevier Ireland Ltd. MARK