Table.
Reporting of intention to treat analysis in published clinical trials (1993-5)
| Total No | No (%) reporting intention to treat | Crude odds ratio for not reporting the use of intention to treat (95% CI) | Logistic regression multivariable model adjusted odds ratio (95% CI) | Odds ratio (95% CI) adjusted for descriptive characteristics | |
|---|---|---|---|---|---|
| All sample | 608 | 290 (47.7) | |||
| Descriptive characteristics of the trials | |||||
| Journal: | |||||
| N Engl J Med | 219 | 122 (55.7) | 1 | 1 | |
| JAMA | 81 | 37 (45.7) | 1.50 (0.90 to 2.50) | 1.64 (0.92 to 2.92) | |
| BMJ | 105 | 44 (41.9) | 1.74 (1.09 to 2.79) | 1.80 (0.96 to 3.39) | |
| Lancet | 203 | 87 (42.9) | 1.68 (1.14 to 2.46) | 1.54 (0.95 to 2.50) | |
| Year of publication: | |||||
| 1995 | 211 | 108 (51.2) | 1 | 1 | |
| 1994 | 195 | 92 (47.2) | 1.17 (0.79 to 1.73) | 1.20 (0.78 to 1.86) | |
| 1993 | 202 | 90 (44.6) | 1.30 (0.89 to 1.92) | 1.14 (0.73 to 1.77) | |
| Country of authors: | |||||
| Europe (except United Kingdom) | 164 | 86 (52.4) | 1 | 1 | |
| United Kingdom | 127 | 61 (48.0) | 1.19 (0.75 to 1.90) | 0.90 (0.52 to 1.55) | |
| United States | 240 | 120 (50.0) | 1.10 (0.74 to 1.64) | 1.24 (0.75 to 2.07) | |
| Other | 77 | 23 (29.9) | 2.59 (1.45 to 4.60) | 2.59 (1.38 to 4.85) | |
| Main specialty of authors: | |||||
| Medical specialties | 432 | 213 (49.3) | 1 | 1 | |
| Surgery or medical-surgical | 106 | 45 (42.5) | 1.32 (0.86 to 2.02) | 1.23 (0.76 to 1.99) | |
| Intensive or emergency care | 37 | 18 (48.6) | 1.03 (0.52 to 2.01) | 1.08 (0.51 to 2.29) | |
| Public health | 16 | 7 (43.8) | 1.25 (0.46 to 3.42) | 1.60 (0.54 to 4.74) | |
| Other | 17 | 7 (41.2) | 1.39 (0.52 to 3.72) | 1.29 (0.44 to 3.82) | |
| Number of participating subjects: | |||||
| >500 | 171 | 109 (63.7) | 1 | 1 | |
| 51 to 500 | 322 | 167 (51.9) | 1.63 (1.11 to 2.39) | 1.68 (1.12 to 2.53) | |
| ⩽50 | 115 | 14 (12.2) | 12.66 (6.68 to 24.10) | 12.43 (6.24 to 24.36) | |
| Source of funding: | |||||
| Pharmaceutical industry | 206 | 129 (62.6) | 1 | 1 | |
| Public agency | 165 | 73 (44.2) | 2.11 (1.39 to 3.20) | 2.11 (1.34 to 3.34) | |
| Other | 126 | 52 (41.3) | 2.38 (1.52 to 3.75) | 2.01 (1.22 to 3.30) | |
| Not reported | 111 | 36 (32.4) | 3.49 (2.14 to 5.68) | 2.35 (1.34 to 4.10) | |
| Methodological characteristics of the trials | |||||
| Outcome: | |||||
| Survival | 142 | 104 (73.2) | 1 | 1 | |
| Other | 466 | 186 (39.9) | 4.12 (2.72 to 6.24) | 2.86 (1.77 to 4.60) | |
| Sample size estimation: | |||||
| Shown | 281 | 167 (59.4) | 1 | 1 | |
| Not shown | 327 | 123 (37.6) | 2.43 (1.75 to 3.37) | 2.28 (1.55 to 3.37) | |
| Compliance with treatment: | |||||
| Stated | 532 | 261 (49.1) | 1 | 1 | |
| Not stated | 76 | 29 (38.2) | 1.56 (0.95 to 2.56) | 1.71 (0.98 to 2.99) | |
| Reporting follow up or withdrawals: | |||||
| Reporting the number of patients withdrawn or lost to follow up | 194 | 100 (51.5) | 1 | 1 | |
| Not giving information about number of patients lost to follow up | 414 | 190 (45.9) | 1.25 (0.89 to 1.76) | 1.45 (0.98 to 2.14) | |
A higher odds ratio means a higher probability of not reporting the use of the intention to treat principle.