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Table 2 Simple logistic regression to compare aspects of trial design, conduct and analysis by types of intervention, time before and after CONSORT (2001) and impact of journal

From: High prevalence of potential biases threatens the interpretation of trials in patients with chronic disease

  Drug, % (n) Non-drug, % (n) Odds ratio (95% CI)(P-value) From 2001, % (n) Before 2001,% (n) Odds ratio (95% CI) (Pvalue) Odds ratio (95% CI) (Pvalue) per increase of 1 unit in impact factor
Number of trials 70 91 - 72 67 - 161
Reporting of between- group comparisons 90% (63) 90% (82) 0.98 (0.35 to 2.80) (0.98) 96% (69) 91% (61) 2.26 (0.54 to 9.44) (0.26) 1.03 (0.97 to 1.11) (0.32)
Primary outcome reported 47% (33) 20% (18) 4.06 (2.02 to 8.14) (< 0.001) 53% (38) 21% (14) 4.23 (2.00 to 8.95) (< 0.001) 1.05 (1.02 to 1.09) (0.001)
Primary outcome is only one measure 31% (22) 13% (12) 3.02 (1.37 to 6.65) (0.006) 36% (26) 12% (8) 4.17 (1.73 to 10.06) (0.001) 1.05 (1.02 to 1.08) (0.002)
No statistical comparison of baseline characteristics 79% (55) 60% (55) 2.40 (1.18 to 4.88) (0.015) 68% (49) 70% (47) 0.91 (0.44 to 1.86) (0.79) 1.03 (1.00 to 1.08) (0.089)
Reporting of handling of missing data 21% (15) 14% (13) 1.63 (0.72 to 3.71) (0.24) 26% (19) 13% (9) 2.31 (0.96 to 5.55) (0.06) 1.04 (1.01 to 1.07) (0.021)
Intention-to-treat analysis reported 53% (37) 33% (30) 2.28 (1.20 to 4.33) (0.01) 53% (38) 39% (26) 1.76 (0.90 to 3.46) (0.10) 1.03 (1.00 to 1.06) (0.047)
Reporting of P values and 9% CI 30% (21) 19% (17) 1.87 (0.89 to 3.89) (0.10) 32% (23) 22% (15) 1.63 (0.76 to 3.47) (0.21) 1.07 (1.04 to 1.11) (< 0.001)