Table 3

Use of procedures in placebo groups of clinical and experimental studies

Procedure% of studies that used each procedure
Experimental (n=58)Clinical (n=111)
Patient’s beliefs and characteristics
1.Select intervention based on patient’s treatment history5575
2.Create positive expectancy765
3.Reduce negative expectancy30
4.Convey a positive therapeutic message through informed consent procedures431
5.Harness sociocultural context00
Practitioner’s beliefs and characteristics
6.Practitioner expectancy01
7.Practitioner’s personal characteristics90
Healthcare setting
8.Active recruitment1416
9.Active retention32
11.Follow a standardised protocol8563
12.Ethical oversight7869
13.Participating in research8684
14.Symptom monitoring9589
15.Enhanced environment50
Treatment characteristics
16.Sham intervention—medication7155
17.Sham interventions—physical3341
18.Sham interventions—attention only25
19.Ineffective substances01
20.Use side effects01
21.Matched treatments4082
22.Maximised treatment procedures223
Patient–practitioner interaction
24.The process of informed consent8877
25.Detailed history1933
28.Patient-centred communication00
29.Extra attention263
30.Continuity of care714