Table 1.
Adherence behavior to tamoxifen treatment (20 mg daily) of Brazilian patients with breast cancer in relation to their demographic and clinical characteristics
| Characteristic | Overall distribution (n = 192) | Adherence at 3 months (n = 163) | OR | P value | Adherence at 6 months (n = 173) | OR | P value | Adherence at 12 months (n = 170) | OR | P value | |||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| High, n (%) | Medium/low, n (%) | 95% CI | High, n (%) | Medium/low, n (%) | 95% CI | High, n (%) | Medium/low, n (%) | 95% CI | |||||
| Ethnicity,a n (%) | |||||||||||||
| White | 139 (72.4) | 89 (74.8) | 30 (25.2) | 0.804 (0.37–1.73) | 0.689 | 98 (79.7) | 25 (20.3) | 2.019 (0.97–4.20) | 0.078 | 78 (62.9) | 46 (37.1) | 0.904 (0.45–1.84) | 0.859 |
| Black | 11 (5.7) | 31 (70.5) | 13 (29.5) | 33 (66.0) | 17 (34.0) | 30 (65.2) | 16 (34.8) | ||||||
| Pardo | 37 (19.3) | ||||||||||||
| Asian/Indian | 5 (2.6) | ||||||||||||
| Educational level,b n (%) | |||||||||||||
| None or incomplete basic | 68 (35.4) | 46 (76.7) | 14 (23.3) | 0.777 (0.37–1.62) | 0.582 | 48 (77.4) | 14 (22.6) | 1.157 (0.56–2.41) | 0.853 | 40 (67.8) | 19 (32.2) | 1.331 (0.68–2.59) | 0.503 |
| Basic | 50 (26.0) | 74 (71.8) | 29 (28.2) | 83 (74.8) | 28 (25.2) | 68 (61.3) | 43 (38.7) | ||||||
| Upper secondary | 53 (27.6) | ||||||||||||
| University (Bachelor/Master/Doctoral) | 21 (10.9) | ||||||||||||
| Age at diagnosis, median (range), years | 51.5 (24–82) | 54 (33–82) | 47 (28–76) | < 0.001 | 54 (24–82) | 49 (32–77) | 0.007 | 56 (24–82) | 48 (28–79) | < 0.001 | |||
| < 65 | 145 (75.5) | 87 (69.0) | 39 (31.0) | 0.270 (0.09–0.82) | 0.018 | 94 (71.8) | 37 (28.2) | 2.913 (1.03–7.98) | 0.038 | 71 (55.9) | 56 (44.1) | 4.86 (1.92–12.34) | < 0.001 |
| 65 | 47 (24.5) | 33 (89.2) | 4 (10.8) | 37 (88.1) | 5 (11.9) | 37 (86.0) | 6 (14.0) | ||||||
| Menopausal status, n (%) | |||||||||||||
| Premenopausal | 127 (66.1) | 74 (66.7) | 37 (33.3) | 0.261 (0.10–0.67) | 0.004 | 81 (70.4) | 34 (29.6) | 2.623 (1.13–6.12) | 0.025 | 60 (53.6) | 52 (46.4) | 4.160 (1.92–9.04) | < 0.001 |
| Postmenopausal | 65 (33.9) | 46 (88.5) | 6 (11.5) | 50 (86.2) | 8 (13.8) | 48 (82.8) | 10 (17.2) | ||||||
| ECOG performance status, n (%) | |||||||||||||
| 0–1 | 187 (97.4) | 116 (73.0) | 43 (27.0) | 1.371 (1.25–1.51) | 0.574 | 126 (75.0) | 42 (25.0) | 1.333 (1.22–1.46) | 0.337 | 103 (62.4) | 62 (37.6) | 1.602 (1.42–1.80) | 0.160 |
| 2–4 | 5 (2.6) | 4 (100.0) | 0 (0.0) | 5 (100.0) | 0 (0.0) | 5 (100.0) | 0 (0.0) | ||||||
| Clinical stage at diagnosis,c n (%) | |||||||||||||
| 0 (in situ) | 2 (1.0) | 93 (72.1) | 36 (27.9) | 0.670 (0.27–1.67) | 0.513 | 104 (75.4) | 34 (24.6) | 1.103 (0.46–2.66) | 1.000 | 85 (61.6) | 53 (38.4) | 1.593 (0.69–3.70) | 0.314 |
| IA/IB | 56 (29.2) | ||||||||||||
| IIA/IIB | 92 (47.9) | ||||||||||||
| IIIA/IIIB/IIIC | 33 (17.2) | 27 (79.4) | 7 (20.6) | 27 (77.1) | 8 (22.9) | 23 (71.9) | 9 (28.1) | ||||||
| IV | 9 (4.7) | ||||||||||||
| Concomitant medications,d n (%) | |||||||||||||
| < 3 medications | 122 (63.6) | 92 (71.3) | 37 (28.7) | 1.877 (0.72–4.91) | 0.274 | 107 (77.0) | 32 (23.0) | 1.393 (0.60–3.22) | 0.504 | 92 (62.2) | 56 (37.8) | 0.616 (0.23–1.67) | 0.477 |
| 3 or more medication | 70 (36.5) | 28 (82.4) | 6 (17.6) | 24 (70.6) | 10 (29.4) | 16 (72.7) | 6 (27.3) | ||||||
| Self‐reported adverse events | |||||||||||||
| Yes | 155 (80.7) | 60 (69.8) | 26 (30.2) | 0.654 (0.32–1.33) | 0.287 | 66 (70.2) | 28 (29.8) | 1.970 (0.95–4.08) | 0.076 | 63 (55.8) | 50 (44.2) | 2.976 (1.42–6.22) | 0.004 |
| No | 37 (19.3) | 60 (77.9) | 17 (22.1) | 65 (82.3) | 14 (17.7) | 45 (78.9) | 12 (21.1) | ||||||
CI, confidence interval; ECOG, Eastern Cooperative Oncology Group; OR, odds ratio.
P: significance value for Fisher's exact test for qualitative variables and Mann–Whitney test for quantitative variable (age).
Black, Pardo, and Asian/Indian were grouped to be tested against white. In Brazil, Pardo is an ethnic/skin color category used by the Brazilian Institute of Geography and Statistics (IBGE) in the Brazilian censuses. The term “pardo” is commonly used to refer to Brazilians of mixed ethnic ancestries. Pardo Brazilians represent a wide range of skin colors and backgrounds. They are typically a mixture of white Brazilian, Afro‐Brazilian, and Native Brazilian. Indian refers to Native Brazilian.
Basic, upper secondary and university levels were grouped to be tested against no instruction.
0 (in situ), IA/IB and IIA/IIB were grouped to be tested against IIIA/IIIB/IIIC and IV.
Concomitant medication in this analysis was assessed to evaluate the impact of polypharmacy in adherence behavior. The main prescribed pharmacologic classes were antihypertensive drugs (29.2%, 29.4%, and 26.3% for 3, 6, and 12 months, respectively) and nonopioid analgesics and nonsteroidal anti‐inflammatory drugs (13.2%, 16.0%, and 22.0% for 3, 6, and 12 months, respectively). Strong cytochrome P450 2D6 (CYP2D6) inhibitors were near 1.0% of all concomitant medications for all time points (0.5%, 0.9%, and 1.2% for 3, 6, and 12 months, respectively).