The number needed to treat for all-cause medication discontinuation in the treatment of schizophrenia: consistency across world geographies and study designs.
BACKGROUND
The number needed to treat (NNT) for all-cause medication discontinuation in large, industry-sponsored, non-randomized, observational studies conducted across world geographies was compared with NNTs from CATIE, an 18-month, NIMH-sponsored, randomized study.


METHODS
NNTs (with 95% confidence intervals) were calculated using data from 3 large Lilly-sponsored, non-randomized, observational studies (EU-SOHO, IC-SOHO, and US-SCAP, n=20 957). Group differences at medication initiation were adjusted by Cox regression modeling. These NNTs were compared with published NNTs for CATIE (phase 1).


RESULTS
NNTs for olanzapine vs. risperidone and for olanzapine vs. quetiapine were similar across the observational studies and similar to those of CATIE. The NNTs for olanzapine vs. oral typical antipsychotics were similar across the observational studies but demonstrated a somewhat stronger effect size than the NNT reported for olanzapine vs. perphenazine in CATIE.


CONCLUSIONS
NNTs for all-cause treatment discontinuation (a proxy measure of a medication's effectiveness from patients' and clinicians' perspectives) appear to be consistent across study designs (non-interventional, observational vs. RCT), study sponsorship (industry vs. independent), and across world geographies, suggesting that antipsychotics differ in this measure.
Novick
D
D
European Outcomes Research, Eli Lilly and Co, Surrey, UK. Novick_diego@lilly.com
Ascher-Svanum
H
H
Zhu
B
B
Brnabic
A
A
Stauffer
V
V
Peng
X
X
Karagianis
J
J
Perrin
E
E
D014150:Antipsychotic Agents / Q000627:therapeutic use*; D001569:Benzodiazepines / Q000627:therapeutic use*; D015340:Epidemiologic Research Design; D005843:Geography; D006801:Humans; D009315:National Institute of Mental Health (U.S.); D000077152:Olanzapine; D010546:Perphenazine / Q000627:therapeutic use*; D016032:Randomized Controlled Trials as Topic; D012109:Research Support as Topic; D012559:Schizophrenia / Q000188:drug therapy / Q000453:epidemiology; D016896:Treatment Outcome; D014481:United States
D014150:Antipsychotic Agents; D001569:Benzodiazepines; D010546:Perphenazine; D000077152:Olanzapine