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Table 4 Odds ratios (95% CI) of mixed/dense mammographic density by screening age, period, and birth cohort

From: Mammographic density in birth cohorts of Danish women: a longitudinal study

Copenhagen N F/MD* Crude odds ratio Adjusted odds ratio Funen N F/MD* Crude odds ratio Adjusted odds ratio
Age 2     Age 2    
50-51 2169|5649 Ref. Ref. 50-51 5125|17997 Ref Ref
52-53 5300|11508 0.87 (0.84-0.90) 0.92 (0.89-0.95) 52-53 6232|16045 0.82 (0.80-0.83) 0.89 (0.86-0.91)
54-55 5548|9414 0.78 (0.76-0.81) 0.89 (0.85-0.92) 54-55 6620|13886 0.74 (0.72-0.76) 0.87 (0.85-0.90)
56-57 5763|7783 0.71 (0.69-0.74) 0.86 (0.82-0.90) 56-57 6749|11790 0.68 (0.66-0.70) 0.88 (0.85-0.91)
58-59 5783|6672 0.67 (0.64-0.69) 0.86 (0.82-0.90) 58-59 6513|10263 0.64 (0.62-0.66) 0.92 (0.89-0.95)
60-61 6015|5992 0.62 (0.60-0.65) 0.85 (0.81-0.90) 60-61 6501|9163 0.60 (0.58-0.62) 0.97 (0.93-1.02)
62-63 6225|5533 0.59 (0.57-0.62) 0.86 (0.82-0.90) 62-63 6519|8215 0.58 (0.56-0.60) 1.05 (1.00-1.10)
64-65 6408|5219 0.55 (0.53-0.58) 0.85 (0.80-0.89) 64-65 6514|7306 0.56 (0.54-0.58) 1.12 (1.07-1.17)
66-67 6685|5201 0.54 (0.52-0.56) 0.86 (0.81-0.91) 66-67 6360|6705 0.56 (0.54-0.58) 1.22 (1.16-1.29)
68-69 6798|5211 0.53 (0.51-0.55) 0.88 (0.83-0.93) 68-69 6183|5979 0.54 (0.52-0.56) 1.30 (1.23-1.37)
70-71 3532|2662 0.50 (0.48-0.53) 0.87 (0.81-0.92) - - - -
Period 2     Period 2    
1991-1993 15814|14177 Ref. Ref. 1994-1995 16100|22959 Ref Ref
1993-1995 13092|12827 0.98 (0.96-1.00) 0.95 (0.93-0.96) 1996-1997 18031|24736 0.84 (0.83-0.86) 0.81 (0.80-0.82)
1995-1997 11668|13313 1.00 (0.98-1.02) 0.94 (0.92-0.96) 1998-1999 15733|27831 0.97 (0.96-0.99) 0.91 (0.90-0.93)
1997-1999 10669|14600 1.01 (0.99-1.04) 0.92 (0.90-0.94) 2000-2001 13452|31823 1.15 (1.13-1.18) 1.05 (1.03-1.07)
1999-2001 8983|15927 1.11 (1.08-1.13) 0.97 (0.95-1.00) - - - -
Birthcohort 1     Birthcohort 1    
1921-1922 1599|1117 Ref. Ref. 1924-1925 1620|1401 Ref. Ref.
1923-1924 3276|2334 1.02 (0.93-1.13) 1.02 (0.93-1.13) 1926-1927 3359|3008 1.01 (0.93-1.11) 1.04 (0.96-1.14)
1925-1926 4508|3258 1.04 (0.94-1.15) 1.05 (0.95-1.16) 1928-1929 4972|4721 1.10 (1.01-1.20) 1.19 (1.09-1.30)
1927-1928 5285|4026 1.11 (1.00-1.22) 1.12 (1.01-1.24) 1930-1931 6579|6518 1.21 (1.11-1.32) 1.35 (1.24-1.48)
1929-1930 6047|4746 1.13 (1.03-1.25) 1.15 (1.04-1.28) 1932-1933 6323|7672 1.42 (1.30-1.54) 1.70 (1.55-1.86)
1931-1932 6166|5315 1.26 (1.14-1.39) 1.28 (1.15-1.42) 1934-1935 6415|8665 1.54 (1.42-1.68) 1.98 (1.81-2.17)
1933-1934 5880|5270 1.32 (1.20-1.46) 1.35 (1.21-1.50) 1936-1937 6573|9729 1.77 (1.63-1.92) 2.40 (2.19-2.63)
1935-1936 5705|5888 1.51 (1.36-1.66) 1.53 (1.37-1.70) 1938-1939 6529|10507 1.99 (1.83-2.17) 2.83 (2.58-3.11)
1937-1938 5547|6556 1.71 (1.55-1.89) 1.71 (1.53-1.90) 1940-1941 6588|12407 2.20 (2.03-2.39) 3.18 (2.90-3.50)
1939-1940 5716|7490 1.91 (1.73-2.10) 1.86 (1.67-2.07) 1942-1943 6638|14842 2.76 (2.55-3.00) 3.90 (3.54-4.28)
1941-1942 4300|7531 2.56 (2.32-2.82) 2.48 (2.22-2.76) 1944-1945 4686|13950 3.27 (3.01-3.55) 4.63 (4.21-5.10)
1943-1944 3270|7371 3.27 (2.97-3.61) 3.12 (2.80-3.48) 1946-1947 2429|9351 4.23 (3.88-4.61) 5.89 (5.32-6.51)
1945-1946 2032|6151 4.40 (3.98-4.87) 4.15 (3.71-4.64) 1948-1949 875|4578 5.93 (5.37-6.55) 7.68 (6.86-8.61)
1947-1948 805|3400 6.21 (5.55-6.95) 5.72 (5.05-6.47) - - - -
1949-1950 90|391 6.22 (4.88-7.92) 5.41 (4.22-6.94) - - - -
  1. Mammography screening program of Copenhagen (1991–2001) and Funen (1994–2001), Denmark.
  2. *F/MD: F=fatty mammographic density; MD=mixed/dense mammographic density.
  3. 1Adjusted for screening age.
  4. 2Adjusted for birth cohort.