Table 2

Characteristics of the trials associated with not reporting either informed consent from participants or REC approval. Separated logistic regression models for reporting of each ethical issue as the outcome. Adjusted odds ratios (OR) and 95 per cent confidence intervals (CI)

Not reporting informed consentNot reporting REC approval
Quality indicatorsAdjusted OR (95% CI)p†Adjusted OR* (95% CI)p†
*Adjusted for journal, country of authors, length of the report, number of participants and source of funding.
†Likelihood ratio test.
‡This was the reference category (ref: reference category).
Concealment of allocation<0.010.01
Yes‡1 (ref)1 (ref)
No1.95 (1.19–3.18)1.72 (1.13–2.60)
Justification of unblinded trials 0.72<0.01
Yes‡1 (ref)1 (ref)
No1.09 (0.69–1.72)1.75 (1.16–2.64)
Type of treatment for control group<0.010.35
Placebo‡1 (ref)1 (ref)
No treatment4.23 (2.15–8.31)1.66 (0.90–3.06)
Alternative active treatment1.96 (1.13–3.39)1.33 (0.82–2.13)
Not a proper control group2.59 (0.64–10.47)1.93 (0.58–6.42)
Reporting of statistical methods 0.090.01
Yes: some information reported‡1 (ref)1 (ref)
No information about statistical methods2.13 (0.88–5.14)2.96 (1.24–7.03)
Sample size estimation<0.010.046
Shown‡1 (ref)1 (ref)
Not shown1.94 (1.22–3.08)1.50 (1.01–2.23)
Rules to stop the trial 0.120.07
Reported‡1 (ref)1 (ref)
Not reported1.21 (0.95–1.54)1.24 (0.98–1.57)
Baseline comparison of groups 0.360.03
Presented‡1 (ref)1 (ref)
Not presented1.31 (0.74–2.32)1.85 (1.09–3.14)
Outcome<0.010.03
Survival‡1 (ref)1 (ref)
Other0.41 (0.24–0.72)0.59 (0.37–0.95)