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Table 1 Study design overview of included publications

From: A literature review on the representativeness of randomized controlled trial samples and implications for the external validity of trial results

  Number (%)  
Cardiology Mental health Oncology Total
Total number of studies 20 (38.5) 17 (32.7) 15 (28.8) 52 (100)
Geography
 USA 8a (40.0) 10 (58.8) 5 (33.3) 23 (44.2)
 The Netherlands 1 (5.0) 3 (17.6) 2 (13.3) 6 (11.5)
 Germany 1 (5.0) 2 (11.8) 2 (13.3) 5 (9.6)
 Canada 3 (15.0) 1 (5.9) 1 (6.7) 5 (9.6)
 Other 7 (35.0) 1 (5.9) 5 (33.3) 13 (25.0)
Methodb
 A only 9 (45.0) 2 (11.8) 7 (46.7) 18 (34.6)
 B only 9 (45.0) 12 (70.6) 6 (40.0) 27 (51.9)
 A and B 2 (10.0) 3 (17.6) 2 (13.3) 7 (13.5)
Comparisons made, Method Ac,d
 Demographics 10 (90.9) 5 (100) 8 (88.9) 23 (92.0)
 Clinical characteristics 8 (72.7) 5 (100) 7 (77.8) 20 (80.0)
 Treatments and procedures 4 (36.4) 2 (40.0) 3 (33.3) 9 (36.0)
 Othere 1 (9.1) 1 (20.0) 0 (0.0) 2 (8.0)
Additional analyses undertaken, Method Bd
 Comparison of baseline characteristics, eligible vs ineligible patients 6 (54.5) 6 (40.0) 1 (12.5) 13 (38.2)
 Common reasons for trial ineligibility 7 (63.6) 14 (93.3) 8 (100) 29 (85.3)
  1. aIncludes one study conducted in the USA and Canada. bMethod A, formal statistical comparison of baseline characteristics between a real-world patient population and patients enrolled in a randomized controlled trial (RCT) in the same disease area; Method B, determination of the proportion of real-world patients who would have been trial eligible or ineligible by review of individual patient medical records followed by application of RCT eligibility criteria. cEach study made multiple comparisons. dPercentages calculated based on total number of studies employing method (for example, Method A studies plus Method A/B studies). eOther comparisons included physical activity relative to “others the same age” (n = 1 cardiology study) and personality traits (n = 1 mental health study)