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Table 2 Proportion of patients shown by treatment group who lost response after Week 8*.

From: Maintenance of response with atypical antipsychotics in the treatment of schizophrenia: a post-hoc analysis of 5 double-blind, randomized clinical trials

Study Treatment Patients who Lost
Response, % (n/N)
p valuea NNT
(95% CI)b
Tran [13] Olanzapine 11.4% (12/105) .002  
  Risperidone 28.7% (27/94)   6 (4, 16)
Kinon [14] Olanzapine 9.6% (5/52) .01  
  Quetiapine 31.1% (14/45)   5 (3, 18)
Breier [17] Olanzapine 16.9% (28/166) .02  
  Ziprasidone 29.3% (36/123)   9 (5, 40)
Kinon [16] Olanzapine 4.9% (3/61) .02  
  Ziprasidone 20.4% (10/49)   7 (4, 34)
Kane [15] Olanzapine 13.1% (20/153) .999  
  Aripiprazole 12.5% (17/136)   -175 (-13, 15)
  1. Abbreviations: PANSS = Positive and Negative Syndrome Scale; CGI-S = Clinical Global Impression Severity Index; n = number of patients who lost response after Week 8; N = number of patients who had response at Week 8; NNT = number needed to treat; CI = confidence interval.
  2. a Fisher's exact test.
  3. b NNT = 1/Absolute Risk Reduction, with 95% CI calculated as previously described [22].
  4. * Proportion of patients who lost response (≥ 20% worsening of PANSS Total score and CGI-S score ≥ 3 occurring any time after Week 8) after having achieved response (≥ 20% improvement over baseline PANSS Total score at Week 8) for 5 randomized, double-blind studies of olanzapine versus another atypical comparator. Also shown are the numbers needed to treat (NNT) with olanzapine rather than comparator to avoid loss of one additional responder.