Table 1. Characteristics on the index date of cases of gastrointestinal bleeding and controls exposed to warfarin.
| Variables | Cases | Controls | |||||
| N = 13,026 | N = 653,209 | Matched | Lower | Upper | |||
| N | % | N | % | OR* | 95% CI | 95% CI | |
| Age | |||||||
| 18–50 | 849 | 6.52 | 85,456 | 13.08 | Reference | ||
| 51–60 | 1,208 | 9.27 | 79,866 | 12.23 | 1.53 | 1.40 | 1.67 |
| 60–70 | 2,336 | 17.93 | 123,848 | 18.96 | 1.91 | 1.76 | 2.06 |
| 70–80 | 3,901 | 29.95 | 179,088 | 27.42 | 2.21 | 2.05 | 2.38 |
| 81+ | 4,732 | 36.33 | 184,951 | 28.31 | 2.61 | 2.43 | 2.81 |
| Gender, male | 4,472 | 34.33 | 238,512 | 36.51 | 0.91 | 0.88 | 0.94 |
| Race | |||||||
| Caucasian | 7,423 | 56.99 | 388,804 | 59.52 | Reference | ||
| African American | 2,305 | 17.70 | 94,479 | 14.46 | 1.28 | 1.22 | 1.35 |
| Other/Unknown | 3,298 | 25.32 | 169,926 | 26.01 | 1.02 | 0.97 | 1.06 |
| Nursing home resident | 3,742 | 28.73 | 121,666 | 18.63 | 1.96 | 1.88 | 2.04 |
| Dementia† | 3,757 | 28.84 | 127,462 | 19.51 | 1.71 | 1.65 | 1.78 |
| Renal disease† | 3,893 | 29.89 | 94,605 | 14.48 | 2.55 | 2.46 | 2.65 |
| Liver disease† | 2,827 | 21.70 | 90,035 | 13.78 | 1.77 | 1.69 | 1.84 |
| Prior GI bleeding‡ | 4,641 | 35.63 | 110,158 | 16.86 | 2.82 | 2.72 | 2.93 |
| Use of acetaminophen§ | 3,189 | 24.48 | 113,315 | 17.35 | 1.55 | 1.49 | 1.61 |
| Use of NSAID§ | 721 | 5.54 | 22,101 | 3.38 | 1.68 | 1.55 | 1.81 |
| Use of levofloxacin§ | 818 | 6.28 | 18,097 | 2.77 | 2.36 | 2.20 | 2.54 |
| Use of PPI§ | 3,300 | 25.33 | 123,180 | 18.86 | 1.48 | 1.42 | 1.54 |
| Number of prior | |||||||
| warfarin prescriptions | |||||||
| 0 | 1,537 | 11.80 | 28,539 | 4.37 | 3.17 | 3.00 | 3.35 |
| 1 | 957 | 7.35 | 28,350 | 4.34 | 2.00 | 1.87 | 2.14 |
| 2 | 746 | 5.73 | 28,846 | 4.42 | 1.54 | 1.43 | 1.66 |
| 3+ | 9,786 | 75.13 | 567,474 | 86.87 | Reference | ||
| Citalopram§ | 162 | 1.24 | 7,314 | 1.12 | 1.11 | 0.95 | 1.30 |
| Escitalopram§ | 146 | 1.12 | 7,109 | 1.09 | 1.03 | 0.87 | 1.22 |
| Fluoxetine§ | 114 | 0.88 | 5,490 | 0.84 | 1.04 | 0.87 | 1.26 |
| Paroxetine§ | 258 | 1.98 | 11,932 | 1.83 | 1.09 | 0.96 | 1.23 |
| Sertraline§ | 316 | 2.43 | 13,850 | 2.12 | 1.15 | 1.03 | 1.29 |
| Venlafaxine§ | 77 | 0.59 | 4,133 | 0.63 | 0.94 | 0.75 | 1.17 |
| Mirtazapine§ | 152 | 1.17 | 6,538 | 1.00 | 1.17 | 1.00 | 1.38 |
| Amitriptyline§ | 122 | 0.94 | 5,001 | 0.77 | 1.22 | 1.02 | 1.47 |
| Doxepin§ | 22 | 0.17 | 531 | 0.08 | 2.10 | 1.37 | 3.21 |
| Nortriptyline§ | 20 | 0.15 | 1,147 | 0.18 | 0.88 | 0.56 | 1.36 |
CI = confidence interval; GI = gastrointestinal; OR = odds ratio; NSAID = non-steroidal anti-inflammatory drug; PPI = proton pump inhibitor.
*Adjusted for matching variables, i.e., index date and state.
†
Ever in the past.
‡
Either an outpatient diagnosis for GI bleeding during warfarin therapy or a hospital admission for GI bleeding before initiating warfarin therapy, excluding the day prior to and the index date.
§
Prescription dispensed 0–29 days prior to the index date.