Table 4 Post-hoc analyses: multivariate regression

Adequate flow diagrams (n = 488)

Adjusted odds ratio (95% CI)

 Year published

1.20 (1.14 to 1.27)

p < 0.001

 Number of participants

1.01 (1.00 to 1.02)

p = 0.005

 Journal impact factor

1.70 (1.44 to 2.02)

p < 0.001

 Multicentre study

0.45 (0.18 to 0.11)

p = 0.083

 Prospective online trial registration

2.44 (1.26 to 4.72)

p = 0.008

Recruitment rate in percent (n = 256)

Coefficient (95% CI)

 Year published

0.03 (− 0.06 to 0.12)

p = 0.517

 Number of participants

0.03 (− 0.06 to 0.12)

p = 0.544

 Journal impact factor

− 4.29 (− 6.16 to − 2.43)

p < 0.001

 Multicentre study

− 3.66 (− 14.79 to 7.43)

p = 0.518

 Prospective online trial registration

− 8.01 (− 15.09 to − 0.93)

p = 0.027

Retention rate in percent (n = 363)

Coefficient (95% CI)

 Year published

− 0.01 (− 0.18 to 0.16)

p = 0.924

 Number of participants

− 0.03 (− 0.05 to 0.00)

p = 0.022

 Journal impact factor

0.25 (− 0.25 to 0.75)

p = 0.332

 Multicentre study

− 0.67 (− 3.32 to 1.98)

p = 0.620

 Prospective online trial registration

− 0.21 (− 2.21 to 1.78)

p = 0.834