Table 2. Temporal Trends in the Impact Factor of Common Medical Journals Between 2001 and 2008.
| Journal | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | 2007 | 2008 | P trend |
| Allergy | 2.852 | 3.666 | 3.161 | 3.496 | 4.120 | 5.334 | 5.014 | 6.204 | 0.0006↑ |
| Am J Resp Crit Care Med | 5.956 | 6.567 | 8.876 | 8.123 | 8.689 | 9.091 | 9.074 | 9.792 | 0.0083↑ |
| Ann Neurol | 8.481 | 8.603 | 7.717 | 8.097 | 7.571 | 8.051 | 8.813 | 9.935 | 0.2575 |
| Ann Rheum Dis | 3.188 | 3.593 | 3.827 | 3.916 | 6.956 | 5.767 | 6.411 | 7.188 | 0.0021↑ |
| Art Rheum/Ar C Res | 7.389 | 7.379 | 7.190 | 7.414 | 7.421 | 7.751 | 7.677 | 6.787 | 0.8108 |
| Brain | 7.407 | 7.122 | 7.967 | 8.201 | 7.535 | 7.617 | 8.568 | 9.603 | 0.0265↑ |
| Chest | 2.480 | 2.969 | 3.264 | 3.118 | 4.008 | 3.924 | 4.143 | 5.154 | 0.0008↑ |
| Circulation | 10.517 | 10.255 | 11.164 | 12.563 | 11.632 | 10.940 | 12.755 | 14.595 | 0.0174↑ |
| Clin Exp Allergy | 3.826 | 3.721 | 3.176 | 3.069 | 3.553 | 3.668 | 3.729 | 3.556 | 0.9845 |
| Clin Inf Dis | 3.545 | 4.750 | 5.393 | 5.594 | 6.510 | 6.186 | 6.750 | 8.266 | 0.0002↑ |
| Crit Care Med | 3.486 | 3.361 | 4.195 | 4.182 | 5.077 | 6.599 | 6.283 | 6.594 | 0.0003↑ |
| Critical Care | 0.701 | 0.876 | 1.911 | 3.214 | 2.932 | 3.116 | 3.834 | 4.553 | 0.0002↑ |
| Diabetes | 7.700 | 8.256 | 8.298 | 8.848 | 8.028 | 7.955 | 8.261 | 8.398 | 0.5307 |
| Diabetes Care | 5.404 | 5.477 | 7.501 | 7.071 | 7.844 | 7.912 | 7.851 | 7.349 | 0.0239↑ |
| Eur Heart J | 5.153 | 6.131 | 5.997 | 6.247 | 7.341 | 7.286 | 7.924 | 8.917 | <.0001↑ |
| Eur Resp J | 2.989 | 2.931 | 2.999 | 3.096 | 3.947 | 5.076 | 5.349 | 5.545 | 0.0006↑ |
| Gastroenterology | 13.020 | 13.440 | 12.718 | 13.092 | 12.386 | 12.457 | 11.673 | 12.591 | 0.0427↓ |
| Gut | 6.170 | 6.323 | 5.883 | 6.601 | 7.692 | 9.002 | 10.015 | 9.766 | 0.0008↑ |
| Hepatology | 8.096 | 9.825 | 9.503 | 10.416 | 9.792 | 10.446 | 10.734 | 11.355 | 0.0038↑ |
| Intens Care Med | 2.314 | 2.041 | 2.971 | 3.304 | 3.724 | 4.406 | 4.623 | 5.055 | <.0001↑ |
| J Allergy Clin Immunol | 5.506 | 6.282 | 6.831 | 7.205 | 7.667 | 8.829 | 8.115 | 9.773 | 0.0001↑ |
| J Am Coll Cardiol | 6.374 | 6.278 | 7.599 | 9.133 | 9.200 | 9.701 | 11.054 | 11.438 | <.0001↑ |
| J Bone Miner Res | 6.230 | 6.329 | 6.225 | 5.436 | 6.527 | 6.635 | 6.004 | 6.443 | 0.6879 |
| J Clin Endocr Metab | 5.160 | 5.199 | 5.873 | 5.778 | 6.020 | 5.799 | 5.493 | 6.325 | 0.0523 |
| J Clin Oncol | 8.530 | 9.868 | 10.864 | 9.835 | 11.810 | 13.598 | 15.484 | 17.157 | 0.0002↑ |
| J Infect Dis | 4.910 | 4.857 | 4.481 | 4.943 | 4.953 | 5.363 | 6.035 | 5.682 | 0.0158↑ |
| J Natl Cancer I | 14.240 | 14.500 | 13.844 | 13.856 | 15.171 | 15.271 | 15.678 | 14.933 | 0.0538 |
| J Neurosci | 8.178 | 8.045 | 8.306 | 7.907 | 7.506 | 7.453 | 7.490 | 7.452 | 0.0037↓ |
| JAMA | 17.569 | 16.586 | 21.455 | 24.831 | 23.494 | 23.175 | 25.547 | 31.718 | 0.0021↑ |
| Lancet | 13.251 | 15.397 | 18.316 | 21.713 | 23.878 | 25.800 | 28.638 | 28.409 | <.0001↑ |
| Lancet Infect Dis | n/a§ | n/a§ | n/a§ | 10.788 | 10.008 | 11.808 | 12.058 | 13.165 | 0.0002↑ |
| Lancet Oncol | n/a§ | n/a§ | 7.411 | 8.794 | 9.608 | 10.119 | 12.247 | 13.283 | 0.0003↑ |
| N Engl J Med | 29.065 | 31.736 | 34.833 | 38.570 | 44.016 | 51.296 | 52.589 | 50.017 | 0.0001↑ |
| Rheumatology | 3.062 | 3.251 | 3.760 | 4.102 | 4.226 | 4.052 | 4.045 | 4.136 | 0.0109↑ |
| Thorax | 4.090 | 4.078 | 4.188 | 5.040 | 6.150 | 6.064 | 6.226 | 7.069 | 0.0002↑ |
Significant increase over time denoted by (↑), while significant decrease is denoted (↓).
§
n/a = not available.