Treatment Response in Schizophrenia

In clinical trials as well as in clinical practice, it is important to evaluate the degree to which a person responds to a particular medication.

Important descriptors of treatment response include:

• complete response
• partial response
• treatment-resistant (refractory)
• relapse

Two psychiatric rating scales that are commonly used to measure treatment response in clinical trials are the BPRS and the PANSS. A decrease of 20% or more in the total BPRS or PANSS score is often used to indicate a general response to treatment. At least 30% of patients with schizophrenia have an inadequate or poor response to typical anti-psychotics. These patients may be considered to be resistant (refractory) to antipsychotic therapy. When treatment-resistant patients are excluded from studies, the average response rate is 50%. Some researchers suggest that these treatment-resistant patients may be in the chronic phase of schizophrenia and are therefore less responsive to treatment compared with patients in an earlier phase of the illness.

Patients are often switched to a different antipsychotic after experiencing problems with the prescribed drug. For example, in any given year, one-third of patients are switched due to lack of efficacy or intolerability. Side effects associated with typical antipsychotics (particularly extrapyramidal symptoms) contribute to rates of nonadherence that approach 50%. Another important measure of treatment response among those who initially benefit from antipsychotic drugs is relapse. As many as 60% of patients treated with a typical antipsychotic experience a relapse after 1 year of therapy.