Table 1.
Distribution of characteristics of women with breast cancer at baseline pooled across databases according to treatment with selective serotonin reuptake inhibitors (SSRIs) that do and do not inhibit cytochrome-P450 2D6 enzyme (CYP2D6). Cohort 1 comprised women exposed to tamoxifen before initiating SSRI treatment. Cohort 2 comprised women exposed to SSRI before initiating tamoxifen treatment. Figures are numbers (percentage) of women unless stated otherwise
| Characteristics | Cohort 1 | Cohort 2 | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Unmatched | Matched (1:10)* | Unmatched | Matched (1:10)* | ||||||||
| CYP2D6 inhibiting SSRIs (n=2268) | Other SSRIs (n=3799) |
CYP2D6 inhibiting SSRIs (n=2026) | Other SSRIs (n=2026/3774) | CYP2D6 inhibiting SSRIs (n=3531) | Other SSRIs (n=4934) |
CYP2D6 inhibiting SSRIs (n=3025) | Other SSRIs (n=3025/4823) | ||||
| Database | |||||||||||
| MAX | 1080 (47.6) | 1253 (33.0) | 911 (45.0) | 911 (45.0) | 1804 (51.1) | 1825 (37.0) | 1444 (47.7) | 1444 (47.7) | |||
| PAAD | 117 (5.2) | 125 (3.3) | 79 (3.9) | 79 (3.9) | 135 (3.8) | 136 (2.8) | 93 (3.1) | 93 (3.1) | |||
| PACE | 267 (11.8) | 381 (10.0) | 249 (12.3) | 249 (12.3) | 241 (6.8) | 238 (4.8) | 174 (5.8) | 174 (5.8) | |||
| Optum | 745 (32.8) | 1899 (50.0) | 740 (36.5) | 740 (36.5) | 1224 (34.7) | 2529 (51.3) | 1209 (40.0) | 1209 (40.0) | |||
| Caremark | 59 (2.6) | 141 (3.7) | 47 (2.3) | 47 (2.3) | 127 (3.6) | 206 (4.2) | 105 (3.5) | 105 (3.5) | |||
| Demographics | |||||||||||
| Mean (SD) age (years) | 57 (14) | 55 (14) | 57 (14) | 56 (14) | 55 (13) | 54 (13) | 55 (13) | 54 (13) | |||
| Index year: | |||||||||||
| 1995-99 | 250 (11.0) | 292 (7.7) | 214 (10.6) | 210 (10.4) | 207 (5.9) | 189 (3.8) | 148 (4.9) | 151 (5.0) | |||
| 2000-04 | 1402 (61.8) | 1717 (45.2) | 1227 (60.6) | 1202 (59.3) | 2239 (63.4) | 2226 (45.1) | 1847 (60.6) | 1831 (60.0) | |||
| 2005-09 | 504 (22.2) | 1224 (32.2) | 473 (23.3) | 504 (24.9) | 857 (24.3) | 1713 (34.7) | 822 (27.0) | 820 (26.9) | |||
| 2010-13 | 112 (4.9) | 566 (14.9) | 112 (5.5) | 110 (5.4) | 228 (6.5) | 806 (16.3) | 233 (7.6) | 248 (8.1) | |||
| Breast cancer characteristics | |||||||||||
| Breast cancer | 1152 (50.8) | 2172 (57.2) | 1034 (51.0) | 1027 (50.7) | 1783 (50.5) | 2727 (55.3) | 1559 (51.1) | 1561 (51.2) | |||
| Stage any time before SSRI†: | |||||||||||
| 0 | 632 (27.9) | 1370 (36.1) | 574 (28.3) | 605 (29.9) | 938 (26.6) | 1585 (32.1) | 826 (27.1) | 839 (27.5) | |||
| I | 614 (27.1) | 1335 (35.1) | 557 (27.5) | 589 (29.1) | 884 (25.0) | 1498 (30.4) | 783 (25.7) | 794 (26.0) | |||
| II | 122 (5.4) | 253 (6.7) | 105 (5.2) | 110 (5.4) | 157 (4.4) | 320 (6.5) | 139 (4.6) | 146 (4.8) | |||
| Screening and treatments | |||||||||||
| Chemotherapy | 322 (14.2) | 678 (17.8) | 294 (14.5) | 296 (14.6) | 522 (14.8) | 895 (18.1) | 455 (14.9) | 458 (15.0) | |||
| Mammography | 792 (34.9) | 1734 (45.6) | 715 (35.3) | 740 (36.5) | 1266 (35.9) | 2278 (46.2) | 1129 (37.0) | 1114 (36.5) | |||
| Mastectomy | 937 (41.3) | 1930 (50.8) | 841 (41.5) | 844 (41.7) | 1154 (32.7) | 1828 (37.0) | 997 (32.7) | 997 (32.7) | |||
| Radiation | 666 (29.4) | 1268 (33.4) | 586 (28.9) | 601 (29.7) | 725 (20.5) | 1233 (25.0) | 641 (21.0) | 642 (21.0) | |||
| Medication utilization | |||||||||||
| Mean (SD) total days supply of tamoxifen before SSRI | 150 (220) | 168 (245) | 150 (217) | 152 (223) | — | — | — | — | |||
| Mean (SD) days supply of SSRI before tamoxifen | — | — | — | — | 8 (7) | 8 (6) | 2 (2) | 2 (2) | |||
| CYP2D6 enzyme inductors | 265 (11.7) | 531 (14.0) | 245 (12.1) | 234 (11.5) | 378 (10.7) | 690 (14.0) | 345 (11.3) | 351 (11.5) | |||
| CYP2D6 enzyme inhibitors | 816 (36.0) | 1015 (26.7) | 676 (33.4) | 673 (33.2) | 400 (11.3) | 674 (13.7) | 356 (11.7) | 341 (11.2) | |||
| Estrogens/hormone therapy | 261 (11.5) | 390 (10.3) | 215 (10.6) | 214 (10.6) | 338 (9.6) | 460 (9.3) | 274 (9.0) | 271 (8.9) | |||
| Healthcare utilization | |||||||||||
| Hospital admission | 688 (30.3) | 1158 (30.5) | 605 (29.9) | 600 (29.6) | 755 (21.4) | 1083 (21.9) | 640 (21.0) | 637 (20.9) | |||
| Mean (SD) combined comorbidity score | 2 (3) | 2 (3) | 2 (3) | 2 (3) | 2 (2) | 2 (2) | 2 (2) | 2 (2) | |||
Caremark=Medicare data linked to pharmacy claims data from CVS Caremark (2005-08); MAX=Medicaid Analytic Extract (2001-06); PAAD=New Jersey Pharmaceutical Assistance to the Aged and Disabled (1995-05); PACE=Pennsylvania Pharmaceutical Assistance Contract for the Elderly (1995-2005); Optum Research Database (2004-13) comprises data on about 40 million UnitedHealth enrollees.
*Women taking CYP2D6 inhibiting SSRI matched on propensity score to at least 1 and at most 10 women taking another SSRI. Random patient in other SSRI group was draw from each matched set to show covariate balance resulting from matching process.
†Data for stages III and IV breast cancer suppressed in accordance with CMS’s current cell size suppression policy, which stipulates that no cell (such as admissions, discharges, patients, services) ≤10 can be displayed.