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Table 1 Participation rates, age and ethnicity of women with breast cancer and controls, Marin County, California, 1997–99

From: Risk factors for breast cancer in a population with high incidence rates

  Controls Cases
Variable N % N %
Eligiblesa 328   401  
Study participantsb     
   Full interview 305 93 300 75
   Short interview 16 5 36 9
   Deceased 0 0 15 4
   Refusal/other 7 2 50 12
   Total 328   401  
Ethnicity     
   White   98   94
Full interview 300   285  
Short interview 16   30  
   Non-white   2   6
Full interview 5   15  
Short interview 0   6  
   Total 321   336  
Age Mean ± SEM Median Mean ± SEM Median
   Full interview 55.1 ± 0.36 55 55.4 ± 0.55 55
   Short interview 55.8 ± 2.83 55 56.7 ± 1.93 58
   All women 55.2 ± 0.54 55 55.6 ± 0.53 55
  1. aCases eligibility: less than 50 years old, newly diagnosed with primary breast cancer between 1 July 1997 and 30 June 1999 or at least 50 years old and diagnosed between 1 July 1997 and 22 March 1999. For controls, 3945 random digit numbers were called: 1640 (41%) either were not in service, were a business, fax or modem number, or were outside Marin County; 920 (23%) were reached but no resident was eligible; 289 (7%) yielded refusal with no additional information; 733 (19%) were in service but were either busy or did not answer (of which 394 were closed out after 10 call attempts and 339 had fewer than 10 call attempts made and were not closed out by the time that control recruitment ended); and 347 (9%) yielded an eligible subject. Of 347 women identified as eligible, 328 were contacted. bFive control women refused any participation and two could not be contacted. Thirty-six cases refused any participation, physicians refused contact for three cases, two cases could not be interviewed in English, we were unable to contact six cases, and three cases were mistakenly coded as ineligible.