OR of receiving research payments and comparison of the received payment value according to physician characteristics
| No (%) | Median (IQR) annual payment value for physicians receiving payments | Adjusted OR (95% CI) | P value | |
| Sex | ||||
| Female | 1866 (1.1) | $501 (127 to 2409) | Ref | – |
| Male | 7590 (2.1) | $928 (167 to 4000) | 1.73 (1.64 to 1.83) | <0.001 |
| Years in practice | ||||
| ≤10 | 423 (0.4) | $376 (100 to 1186) | Ref | – |
| 11–20 | 2724 (1.7) | $651 (200 to 2890) | 3.51 (3.16 to 3.89) | <0.001 |
| 21–30 | 3017 (2.2) | $868 (250 to 3980) | 4.16 (3.74 to 4.62) | <0.001 |
| >30 | 3292 (2.2) | $1110 (283 to 4425) | 3.46 (3.11 to 3.85) | <0.001 |
| Medical school attended* | ||||
| Top-20 school in USA | 1793 (3.0) | $1005 (299 to 4237) | Ref | – |
| US schools ranked 21–50 | 1838 (1.9) | $892 (217 to 3686) | 0.73 (0.68 to 0.78) | <0.001 |
| Other schools | 5825 (1.5) | $751 (219 to 3438) | 0.61 (0.57 to 0.64) | <0.001 |
| Specialty | ||||
| Primary care | ||||
| Internal Medicine | 1217 (1.2) | $760 (197 to 3333) | Ref | – |
| Family Medicine | 439 (0.5) | $646 (94 to 2823) | 0.46 (0.40 to 0.52) | <0.001 |
| Paediatrics | 91 (1.4) | $602 (271 to 1994) | 1.29 (1.02 to 1.63) | 0.35 |
| Hospitalist | 17 (0.3) | $1245 (400 to 2674) | 0.24 (0.15 to 0.38) | <0.001 |
| Surgery | ||||
| Orthopaedic | 465 (2.2) | $2240 (536 to 6650) | 1.42 (1.25 to 1.62) | 0.65 |
| Neurosurgery | 209 (4.6) | $1400 (333 to 4933) | 3.01 (2.52 to 3.59) | <0.001 |
| Thoracic/Vascular | 100 (3.6) | $350 (137 to 1096) | 2.19 (1.77 to 2.72) | <0.001 |
| Urology | 192 (2.4) | $717 (238 to 2703) | 1.56 (1.32 to 1.86) | <0.001 |
| Colorectal | 33 (3.5) | $466 (158 to 1900) | 2.36 (1.58 to 3.52) | <0.001 |
| General | 467 (1.8) | $437 (200 to 1330) | 1.31 (1.15 to 1.49) | <0.001 |
| Plastic | 46 (1.8) | $1197 (197 to 4483) | 1.12 (0.83 to 1.52) | 0.47 |
| Otolaryngology | 150 (1.8) | $446 (197 to 3771) | 1.25 (1.03 to 1.52) | 0.03 |
| Obstetrics/Gynaecology | 505 (1.8) | $331 (17 to 1839) | 1.54 (1.36 to 1.74) | <0.001 |
| Specialists | ||||
| Endocrinology | 216 (4.9) | $948 (147 to 5094) | 4.02 (3.45 to 4.69) | <0.001 |
| Rheumatology | 244 (6.9) | $688 (171 to 3615) | 5.62 (4.77 to 6.62) | <0.001 |
| Haematology/Oncology | 1040 (11.1) | $804 (183 to 2673) | 8.90 (8.00 to 9.90) | <0.001 |
| Neurology | 564 (4.9) | $653 (215 to 3608) | 3.93 (3.47 to 4.44) | <0.001 |
| Dermatology | 360 (3.5) | $2208 (363 to 10 648) | 2.89 (2.52 to 3.31) | <0.001 |
| Cardiology | 567 (3.0) | $754 (183 to 3159) | 1.95 (1.73 to 2.20) | <0.001 |
| Allergy/Immunology | 155 (5.4) | $3356 (550 to 21 467) | 4.12 (3.39 to 5.00) | <0.001 |
| Ophthalmology | 476 (3.0) | $1311 (418 to 5745) | 2.09 (1.83 to 2.38) | <0.001 |
| Gastroenterology | 361 (3.5) | $1667 (386 to 4330) | 2.33 (2.01 to 2.69) | <0.001 |
| Infectious Diseases | 94 (2.0) | $1102 (290 to 3770) | 1.50 (1.21 to 1.85) | <0.001 |
| Pulmonology | 122 (2.2) | $795 (280 to 3902) | 1.51 (1.23 to 1.85) | <0.001 |
| Paediatric Specialty | 138 (3.9) | $479 (180 to 1130) | 3.00 (2.49 to 3.61) | <0.001 |
| Psychiatry | 240 (1.1) | $1344 (459 to 7083) | 0.87 (0.74 to 1.01) | 0.07 |
| Radiology | 241 (1.0) | $2206 (525 to 7206) | 0.68 (0.57 to 0.82) | <0.001 |
| Nephrology | 141 (2.0) | $604 (263 to 3550) | 1.46 (1.21 to 1.76) | <0.001 |
| Rehabilitation | 34 (0.5) | $909 (188 to 3812) | 0.37 (0.26 to 0.53) | <0.001 |
| Emergency Medicine | 122 (0.7) | $567 (228 to 2000) | 0.50 (0.41 to 0.61) | <0.001 |
| Anaesthesiology | 124 (0.3) | $1343 (399 to 4042) | 0.25 (0.21 to 0.31) | <0.001 |
| Others† | 286 (1.0) | $728 (233 to 2493) | 0.76 (0.66 to 0.87) | <0.001 |
*Defined based on the U.S. News & World Report ranking (research ranking) in 2017.
†Others include surgical oncology, oral surgery, radio oncology, pathology, nuclear medicine and so on.