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Table 2 Power calculations for continuous outcome measures

From: TAILOR – tapered discontinuation versus maintenance therapy of antipsychotic medication in patients with newly diagnosed schizophrenia or persistent delusional disorder in remission of psychotic symptoms: study protocol for a randomized clinical trial

Outcome

Lowest clinically relevant difference

Expected standard deviation

Calculated power

Reference

Antipsychotic haloperidol equivalents

1.5

3

98%

Own unpublished data

Negative symptoms (negative dimension, based on mean of four global SANS scores)

0.4

1.2

75%

Petersen [45]

Cognition, overall score (BACS total)

15

42

80%

Melau [46]

Client satisfaction (CSQ)

2

5

88%

Petersen [45]

Social function (GSDS)

1.6

4.5

80%

Standard deviation based on [22]. Lowest clinically relevant difference is not known, but is set to Cohen’s d = 0.356, i.e.,low-to-moderate effect size

  1. CSQ Patient Satisfaction Questionnaire, BACS Brief Assessment of Cognition in Schizophrenia, GSDS, Groningen Social Disabilities Schedule, SANS Schedule for Assessment of Negative Symptoms