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Table 3 Sensitivity and subgroup analysis for SSRI use and breast cancer mortality

From: Selective serotonin reuptake inhibitor use and breast cancer survival: a population-based cohort study

 

Non-usersa

Users

Unadjusted HR (95% CI)

Adjusted HRb (95% CI)

n

Person-years

Deathsc

n

Person-years

Deaths

Main analysis

18,885

105,433

2539

4784

20,722

514

1.17 (1.07, 1.29)

1.27 (1.16, 1.40)

Death definition

 All-cause

18,885

105,433

4358

4784

20,722

933

1.16 (1.08, 1.25)

1.33 (1.23, 1.43)

 Primary or secondary breast cancer cause

18,885

105,433

2965

4784

20,722

593

1.16 (1.06, 1.27)

1.28 (1.17, 1.40)

Exposure definition

 Year before diagnosis

21,768

138,969

2810

1901

10,855

243

1.09 (0.96, 1.24)

1.18 (1.03, 1.34)

 Year after diagnosis

20,999

113,219

2700

2670

12,935

353

1.11 (1.00, 1.25)

1.23 (1.10, 1.38)

Exposure lag

 6 months

18,541

114,762

2455

5128

23,195

598

1.25 (1.14, 1.36)

1.36 (1.24, 1.49)

 2 years

19,635

87,457

1912

4034

16,319

360

1.14 (1.02, 1.28)

1.22 (1.09, 1.37)

Prior antidepressant medicationd

1769

9316

258

2019

8861

241

1.11 (0.93, 1.33)

1.21 (1.00, 1.45)

SSRI vs other antidepressant medication

3791

17,390

435

4784

20,722

514

1.02 (0.89, 1.15)

1.06 (0.93, 1.20)

Tamoxifen use

 Non-user

11,110

52,864

1674

2790

10,678

341

1.16 (1.03, 1.30)

1.25 (1.11, 1.41)

 User

7775

52,569

865

1994

10,044

173

1.13 (0.96, 1.34)

1.36 (1.15, 1.61)

 Adherant usere

3612

26,159

489

882

4645

86

1.10 (0.87, 1.38)

1.30 (1.03, 1.65)

Adjustment

 Excluding ‘previous hot flush’ diagnosisf

18,885

105,433

2539

4784

20,722

514

1.17 (1.07, 1.29)

1.24 (1.12, 1.36)

 CC lifestyleg

12,568

70,673

1561

3290

14,116

327

1.18 (1.05, 1.33)

1.24 (1.10, 1.40)

 MI lifestyle

18,885

105,433

2539

4784

20,722

514

1.17 (1.07, 1.29)

1.26 (1.14, 1.38)

 CC diagnosish

7388

40,419

813

1863

7980

164

1.13 (0.95, 1.34)

1.14 (0.96, 1.35)

 MI diagnosis

18,885

105,433

2539

4784

20,722

514

1.17 (1.07, 1.29)

1.27 (1.14, 1.40)

  1. HR hazard ratio, CI confidence interval, SSRI selective serotonin reuptake inhibitor
  2. aExcept for ‘SSRI vs other anti-hypertensive medication’ where patients who received a different anti-hypertensive medication serve as the reference group
  3. bAdjusted for age, deprivation, year of diagnosis, cancer treatment within 6 months (radiotherapy, chemotherapy, surgery, tamoxifen, aromatase inhibitors), comorbidities (cerebrovascular disease, chronic pulmonary disease, congestive heart disease, diabetes, liver disease, myocardial infarction, peptic ulcer disease, peripheral vascular disease, renal disease), hot flushes and pre-diagnosis use of hormone replacement therapy or oral contraceptives
  4. cDeaths with a primary cause of breast cancer unless otherwise stated
  5. dSSRI users vs non-users, restricted to patients with an antidepressant prescription in the year prior to cancer diagnosis
  6. eDefined as having been prescribed at least 150 defined daily doses of tamoxifen in the first six months after cancer diagnosis
  7. fNot adjusting for a previous hot flush diagnosis
  8. gComplete case (CC), additionally adjusted for smoking, obesity and alcohol consumption
  9. hMultiply imputed (MI), additionally adjusted for stage and grade