Table 2 Univariable and multivariable GEE logistic regression derived Odds Ratios (OR) and 95% confidence intervals (CI) for the effect of speciality journal, continent of corresponding author, study type, ethical approval, involvement of statistician, study registration, conflict of interest and impact factor on the likelihood of reporting a significant result

Speciality journal

General oral health journals

Reference

Orthodontics

0.09 (0.03,0.36)

0.001

0.13 (0.04, 0.46)

0.001

Periodontology

0.15 (0.04, 0.55)

0.004

0.23 (0.07, 0.78)

0.018

Endodontics

0.24 (0.06, 0.98)

0.05

0.19 (0.05, 0.73)

0.015

Oral and Maxillofacial surgery

0.43 (0.04, 0.48)

0.002

0.15 (0.04, 0.49)

0.002

Pedatrics

0.13 (0.03,0.56)

0.006

0.15 (0.04, 0.60)

0.008

Prosthodontics

0.19 (0.05, 0.74)

0.016

0.14 (0.04, 0.49)

0.002

Continent of corresponding author

Europe

Reference

Americas

1.26 (0.87, 1.81)

0.215

1.05 (0.72, 1.54)

0.793

Asia or other

1.60 (1.12, 2.30)

0.01

1.49 (1.02,2.19)

0.037

Study type

In-vitro

Reference

Reference

Interventional

0.22 (0.15, 0.34)

<0.001

0.35 (0.22,0.58)

<0.001

Observational

0.53 (0.35, 0.80)

0.003

0.56 (0.36, 0.89)

0.013

Ethical approval

Not reported

Reference

Approval obtained

0.69 (0.48, 1.02)

0.06

Involvement of statistician

No

Reference

Yes

0.73 (0.45, 1.19)

0.206

Study registration

No

Reference

Reference

Yes

0.22(0.14, 0.32)

<0.001

0.32 (0.19,0.53)

<0.001

Conflict of interest

No

Reference

Yes

1.05 (0.49, 2.21)

0.897

Impact factor

Per unit

1.32 (0.96,1.81)

0.08