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Table 2 Characteristics of the study sample

From: Digoxin treatment is associated with an increased incidence of breast cancer: a population-based case-control study

Variable Cases (n = 5,565) Controls (n = 55,650)
Age on index date (years):   
   55 to 64 2,116 (38) 21,160 (38)
   65 to 74 1,800 (32) 18,000 (32)
   75 to 84 1,356 (24) 13,560 (24)
   ≥ 85 293 (5.3) 2,930 (5.3)
Medical history, n (%):   
   Congestive heart failure 160 (2.9) 1,337 (2.4)
   Atrial fibrillation/flutter 224 (4.0) 1,819 (3.3)
   Prediagnosis mammographya   
< 1 year: 417 (81) 84 (1.6)
1 to < 2 years: 3 (0.6) 84 (1.6)
2 to < 3 years: 9 (1.7) 84 (1.6)
≥ 3 years: 17 (3.3) 130 (2.5)
   Myocardial infarction 123 (2.2) 1,492 (2.7)
   Chronic pulmonary disease 334 (6.0) 3,125 (5.6)
   Peripheral vascular disease 167 (3.0) 1,563 (2.8)
   Cerebrovascular disease 275 (4.9) 2,842 (5.1)
   Lymphoma 12 (0.2) 155 (0.3)
   Other solid tumor 0 0
   Liver disease 44 (0.8) 403 (0.7)
   Diabetes (type I or II) 215 (3.9) 1,706 (3.1)
   Diabetes with end-organ complication 85 (1.5) 591 (1.1)
   Renal disease 35 (0.6) 446 (0.8)
Other drug exposures, n (%):   
   Hormone replacement therapy 2,062 (37) 17,582 (32)
   Anticoagulants 231 (4.2) 2,109 (3.8)
   NSAIDs 3,106 (56) 29,964 (54)
   Aspirin, low-dose (< 150 mg) 205 (3.7) 2,004 (3.6)
   Aspirin, high-dose (≥ 150 mg) 505 (9.1) 4,878 (8.8)
  1. aScreening mammography data were only available from 2001 onwards. We restricted the mammography analysis to cases and controls with index dates after 1 January 2006, when screening mammography would have been most common in Denmark. Categories reflect time elapsed between most recent mammogram and index date; proportion denominators are the total number of cases (n = 516) or controls (n = 5,160) in the restricted data set.
  2. NSAID, non-steroidal anti-inflammatory drug.