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Table 1 Characteristics of the 51 included trials

From: Treatment success in pragmatic randomised controlled trials: a review of trials funded by the UK Health Technology Assessment programme

Characteristic No. of trials (%)
Study design  
   Parallel 49 (96)
   Factorial 2 (4)
Number of arms  
   2 arms 38 (75)
   3 arms 8 (16)
   4 arms 2 (4)
   5 arms 3 (6)
No. of participants  
   Total number of participants in all trials 48,323
Mean number of participants per trial
(excluding outlier involving 14,802 participants)
670
   Median number of participants per trial (IQR) 457 (212 to 806)
Trials achieving sample size  
   Trials achieving at least required sample size 18 (35%)
   Trials recruiting 80% of original target 34 (67%)
Intervention evaluated  
   Service Delivery 11 (22)
   Surgery 8 (16)
   Psychological Therapy 5 (10)
   Physical Therapies 5 (10)
   Diagnostic 5 (10)
   Drug 4 (8)
   Devices 4 (8)
   Social Care 3 (6)
   Education and Training 2 (4)
   Complementary Therapies 2 (4)
   Vaccines and Biologicals 1 (2)
   Diet 1 (2)
Disease (ICD10 chapter)  
M00-M99 Diseases of the musculoskeletal system and
connective tissue
8 (16)
G00-G99 Diseases of the nervous system 8 (16)
I00-I99 Diseases of the circulatory system 8 (16)
Z00-Z99 Factors influencing health status and contact with
health services
6 (12)
F00-F99 Mental and behavioural disorders 6 (12)
O00-O99 Pregnancy, childbirth and the puerperium 4 (8)
K00-K93 Diseases of the digestive system 3 (6)
N00-N99 Diseases of the genitourinary system, 3 (6)
C00-D48 Neoplasms 2 (4)
LOO-L99 Diseases of the skin and subcutaneous tissue 1 (2)
P00-P96 Certain conditions originating in the perinatal
Period
1 (2)
S00-T98 Injury, poisoning and certain other consequences
of external causes
1 (2)
Primary outcome types in the 51 trials*  
   Symptom score or measurement of depression/pain 13 (25)
   Quality of life measure (including generic and disease specific) 10 (19)
   Positive event rate (e.g. improvement in symptoms) 10 (19)
   Adverse event rate (e.g. post operative nausea and vomiting) 9 (17)
   Survival/mortality 6 (11)
   Measurement of function 4 (8)
   Other 1 (2)
Intention to treat analysis  
   Yes 48 (94)
   No 0 (0)
   Unclear 3 (6)
Blinding / Masking  
   Participant blinded 2 (4)
   Outcome assessor blinded 13 (25)
   Person administering intervention blinded 1 (2)
   No blinding 38 (74)
Combination of blinding / masking  
   Participant and outcome assessor blinded only 2 (4)
   Administrator and outcome assessor blinded only 1 (2)
   Outcome assessor blinded only 10 (20)
   No blinding 38 (74)
  1. *This adds up to 53 because two trials included 2 different types of primary outcome