To the Editor: The article by Kreyenbuhl and colleagues (1) in the July issue illustrates an important topic in the treatment of patients with schizophrenia, because we know that 10% to 30% of our patients do not respond to standard treatment. The literature on the efficacy of clozapine for these patients is abundant. Therefore, the results of this study—that neither adding another antipsychotic nor switching to some other antipsychotic is an effective way of treating resistant schizophrenia—are hardly surprising. Moreover, Kreyenbuhl and colleagues did not follow the patients for whom the antipsychotic was stopped. Perhaps these patients did as well as those whose medication was switched. Moreover, it is shocking that only one patient for whom a medication was added (1%) and only 11 (8%) whose mediation was switched received clozapine.
Unfortunately, data on the adherence of the patients were also not reported. The Clinical Antipsychotic Trials in Intervention Effectiveness study (2) showed that approximately 25% to 30% of patients did not remain on their medication (2). Even for patients who persist in the use of medication, at least 20% do not take the medication as prescribed (3). Lack of adherence may reflect lack of efficacy (4).
In Kreyenbuhl and colleagues' study 14% of the patients for whom a medication was added and 10% of those patients whose medication was switched used a long-acting injection. It is our clinical impression that especially in this group, in which the adherence question does not arise, adding clozapine has a substantial beneficial effect. Currently, we ask all our patients whether they prefer oral medication or a long-acting injection (5).
Dr. Hovens is affiliated with Delta Psychiatric Teaching Center, Poortugaal, the Netherlands, and the Institute of Psychology, Erasmus University, Rotterdam. Dr. Loonen holds the Delta chair on pharmacotherapy in psychiatric patients, Department of Pharmacotherapy, University of Groningen, the Netherlands.
Kreyenbuhl J, Marcus SC, West JC, et al: Adding or switching antipsychotic medications in treatment-refractory schizophrenia. Psychiatric Services 58:983—990, 2007
Lieberman JA, Stroup TS, McEvoy JP, et al: Effectiveness of antipsychotic drugs in patients with chronic schizophrenia. New England Journal of Medicine 353:1209—1223, 2005
Cooper D, Moisan J, Gregoire JP: Adherence to atypical antipsychotic treatment among newly treated patients: a population-based study in schizophrenia. Journal of Clinical Psychiatry 68:815—825, 2007
Gilmer TP, Dolder CR, Lacro JP, et al: Adherence to treatment with antipsychotic medication and health care costs among Medicaid beneficiaries with schizophrenia. American Journal of Psychiatry 161:692—699, 2004
Hovens JE, Roman B, Van Dinther R: Patients with schizophrenia prefer long-acting injections. Schizophrenia Research 81:S84, 2006