Table 1. Study Features Associated with Annual Citation Rate.
| Variable | Number of articles | Univariable Analysis (unstandardized regression coefficients (95% CI)) | p-value | Multivariable Analysis (unstandardized regression coefficients (95% CI)) | p-value |
| Industry funding | <0.001 | 0.002 | |||
| -no | 246 | reference category | See interaction term * | ||
| -yes | 82 | 19.9 (12.2 to 27.5) | |||
| Industry favoring result | <0.001 | 0.004 | |||
| -no | 252 | reference category | See interaction term * | ||
| -yes | 76 | 19.4 (11.6 to 27.3) | |||
| Industry funding & Industry favoring result (interaction term) * | n/a† | 0.02 | |||
| -no industry funding and no industry favoring result | 212 | n/a† | reference category | ||
| -industry funding, but no industry favoring result | 40 | n/a† | 3.9 (−6.1 to 14.0) | ||
| -no industry funding, but industry favoring result | 34 | n/a† | 2.5 (−8.2 to 13.2) | ||
| -industry funding and industry favoring result | 42 | n/a† | 25.7 (8.5 to 42.9) | ||
| Clinical category | 0.001 | 0.004 | |||
| -other | 125 | reference category | reference category | ||
| -cardiovascular | 57 | 17.8 (8.1 to 27.5) | 13.31 (3.9to 22.3) | ||
| -general medicine | 29 | 8.4 (−4.1 to 20.9) | 9.1 (−3.2 to 21.5) | ||
| -oncology | 30 | 13.5 (1.2 to 25.8) | 12.6 (1.2 to 24.0) | ||
| -infectious disease | 62 | −0.7 (−10.1 to 8.7) | −2.9 (−11.7 to 5.8) | ||
| -obstetrics & gynaecology | 25 | −7.7 (−21.0 to 5.6) | −6.5 (−19.0 to 5.9) | ||
| Group authorship | <0.001 | 0.01 | |||
| -no | 260 | reference category | reference category | ||
| -yes | 68 | 20.3 (12.2 to 28.5) | 11.1 (2.7 to 19.5) | ||
| Journal of publication | <0.001 | 0.002 | |||
| -NEJM | 102 | reference category | reference category | ||
| -JAMA | 100 | −8.6 (−17.2 to 0.0) | −9.7 (−18.0 to −1.5) | ||
| -Lancet | 126 | −16.3 (−24.4 to −8.2) | −13.1 (−20.1 to −5.6) | ||
| Sample size (log10 transformed) | 3.1 (0.2 to 6.0) | 0.04 | 2.8 (0.1 to 5.7) | 0.04 | |
| News media coverage of article | <0.001 | n/a† | |||
| -no | 231 | reference category | n/a† | ||
| -yes | 97 | 13.5 (6.1 to 20.9) | n/a† | ||
| Location of study | 0.001 | n/a† | |||
| -not in United States | 151 | reference category | n/a† | ||
| -partly/exclusive in United States | 177 | 11.9 (5.2 to 18.7) | n/a† | ||
| Study design | 0.01 | n/a† | |||
| -randomized | 92 | 13.4 (−2.1 to 28.8) | n/a† | ||
| -prospective | 108 | 1.2 (−14.1 to 16.4) | n/a† | ||
| -retrospective | 92 | −2.4 (−17.8 to 13.0) | n/a† | ||
| -meta-analysis | 15 | 2.8 (−18.4 to 23.9) | n/a† | ||
| -survey | 19 | reference category | n/a† | ||
| Month of publication (from 1 = October 1999 to 6 = March 2000) | 0.7 (−1.3 to 2.7) | 0.50 | n/a† |
95% CI = 95% confidence interval
†
n/a = not applicable (variable was not included in the model)
*
Since a significant interaction term between these two variables was included in the final multivariable model, their effects are dependent on each other and are presented together.