Risk of Treatment Failure: Response to Czobor and Volavka

To the Editor: We thank Drs. Czobor and Volavka for their comments on our study. Their first comment states that the absolute risk of treatment failure decreases with longer prior antipsychotic exposures. Table 1 in our article presents the incidence rate for each discontinuation group. The highest incidence rate, 25.3 per 100 person-years, is seen for those patients with the longest (more than 5 years) prior antipsychotic exposure.

The second comment concerns relative risk, stating that the relative risk increases with time were not due to the increase in relapse rates among discontinuers but were mostly driven by the progressively lower risks of relapse in the continuers group. We have already stated this in the first paragraph of the Discussion section: “While the incidence rate of treatment failure and rehospitalization decreased as function of duration of the preceding antipsychotic use among patients who continued to use antipsychotics, this was not the case among those who discontinued treatment.” The aim of our study was to compare the relative risk of treatment failure for discontinuation versus continuation. In other words, the important question for the patient and the doctor is: to continue or not to continue antipsychotic treatment.

We agree with the third comment that further analyses may be useful. However, we would like to emphasize the excess mortality among the non-rehospitalized patients not using antipsychotics.