Supplementary data


Conceptually trials also can be subdivided into observational and interventional.

Looking separately on enrollment for different intervention types, for device related trials edu and com classes have in average higher enrollment into observational trials than into interventional, for other three classes the tendency is opposite, maximal enrollment for all classes higher for interventional trials. For drug related trials gov and com classes showed higher maximal enrollment for observational trials, all except edu have higher enrollment for observational trials in average. For procedure related trials col, com and hos have more in average observational trial enrollment, while gov and edu have more interventional. Maximum in this case for all except edu classes is higher for interventional trials. Overall, maximal average number of participants has been observed for drugs' observational trials, especially for com and gov classes, minimal average number corresponds to drugs' interventional trials. com class has biggest average number of enrolled participants, while hos has the smallest among investigated five classes. Device related trials contrary to ones related to drugs or procedure, have higher average enrollment for interventional than observational trials. Detail are given in Table 10.

As mentioned before companies are very focused on drugs trials, moreover, they conduct a significant number (comparatively to other classes) not only interventional studies but observational as well .

Table 10: Clinical trials enrollment for different classes and intervention types overall vs interventional vs observational study type; only trials with overall status 'Completed' or 'Active, not recruiting' were considered.



class

trials

max

average

total

trials

max

average

total

trials

max

average

total

interventional

observational

all

Device

col

145

81597

870

126215

19

8314

643.79

12232

164

81597

844.19

138447

com

1003

100000

469

470285

164

8053

490.22

80396

1167

100000

471.88

550681

gov

131

45000

599

78527

18

750

144.11

2594

149

45000

544.44

81121

hos

293

9346

193

56441

55

1297

143.71

7904

348

9346

184.9

64345

edu

539

20000

213

114864

80

13000

336.03

26882

619

20000

228.99

141746


Drug

col

957

75000

298

284779

16

4200

483.63

7738

973

75000

300.63

292517

com

8059

30000

232

1868762

507

2323608

6887.3

3491862

8566

2323608

625.8

5360624

gov

1863

16000

149

276767

44

30000

1101.05

48446

1907

30000

170.54

325213

hos

1341

4657

102

136263

40

1497

164.43

6577

1381

4657

103.43

142840

edu

2675

46000

198

530297

95

1500

137.28

13042

2770

46000

196.15

543339


Procedure

col

177

6000

207

36662

43

44587

1210.84

52066

220

44587

403.31

88728

com

154

2500

216

33235

31

1944

449.81

13944

185

2500

255.02

47179

gov

343

100000

705

241881

35

10800

543.57

19025

378

100000

690.23

260906

hos

533

21000

274

146116

127

9000

322.41

40946

660

21000

283.43

187062

edu

798

99999

439

350001

161

10224

297.31

47867

959

99999

414.88

397868