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Table 1 Summary of trial characteristics

From: Placebo response and effect in randomized clinical trials: meta-research with focus on contextual effects

Characteristic

Trials (k = 186)

Number of patients

16,655

Proportion of women (SD)

58.6 (28.6)

Mean age, years (SD)

39.9 (17.1)

Condition

 Abortion, n (%)

3 (1.6)

 Anxiety, n (%)

3 (1.6)

 Asthma, n (%)

3 (1.6)

 Cancer, n (%)

5 (2.9)

 Dementia, n (%)

3 (1.6)

 Depression, n (%)

9 (4.8)

 Fibromyalgia, n (%)

3 (1.6)

 Headache, n (%)

8 (4.3)

 Hypertension, n (%)

7 (3.8)

 Insomnia, n (%)

5 (2.9)

 Low back pain, n (%)

3 (1.6)

 Obesity, n (%)

8 (4.3)

 Osteoarthritis, n (%)

5 (2.9)

 Phobia, n (%)

3 (1.6)

 Schizophrenia, n (%)

3 (1.6)

 Smoking, n (%)

9 (4.8)

 Surgery/procedure, n (%)

45 (24.2)

 Othera, n (%)

61 (32.8)

No. center

 Single, n (%)

97 (52.1)

 Unclear, n (%)

56 (30.1)

 Multi, n (%)

33 (17.7)

Type of intervention

 Psychological, n (%)

62 (33.3)

 Pharmacological, n (%)

56 (30.1)

 Physical, n (%)

68 (36.6)

Study duration

 < 4 weeks, n (%)

83 (44.6)

 4 to 8 weeks, n (%)

44 (23.7)

 8 to 12 weeks, n (%)

27 (14.5)

 > 12 weeks, n (%)

32 (17.2)

Outcome domain

 Anxiety, n (%)

9 (4.8)

 Depression, n (%)

10 (5.4)

 Diastolic blood pressure, n (%)

7 (3.8)

 Medication use, n (%)

9 (4.8)

 Nausea, n (%)

9 (4.8)

 Pain, n (%)

53 (28.5)

 Sleep disturbance, n (%)

6 (3.2)

 Smoking cessation, n (%)

9 (4.8)

 Weight, n (%)

8 (4.3)

 Otherb, n (%)

66 (35.5)

High risk, n (%)

170 (91.4)

  1. aConditions investigated in less than three trials, bOutcomes reported in less than three trials