1. Use logistic regression methods to assess whether there is an association between ovarian cancer risk and duration of OC use while controlling for age. Provide a two-sided p-value. Assume that the average duration of use in the < 3 years group = 1.5 years and in the 3+ years group = 4 years. Also, provide an estimate of the OR relating ovarian cancer risk per year of use of OCs and a 95% CI?

2. Use logistic regression methods to assess whether there is an association between ever use of OCs and ovarian cancer risk, while controlling for age. Also, provide an estimate of the OR and a 95% CI about this estimate. 

Cancer

A case€“control study was performed early in the Nurses€™ Health Study (NHS) to assess the possible association between oral contraceptive (OC) use and ovarian cancer [50]. Forty seven ovarian cancer cases were identified at or before baseline (1976). For each case, 10 controls matched by year of birth and with intact ovaries at the time of the index woman€™s diagnosis were randomly chosen from questionnaire respondents free from ovarian cancer. The data in Table 13.58 were presented.

Table 13.58 Duration of OC use by age at diagnosis among women with ovarian cancer and controls

 

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Duration OC use Age at diagnosis Never <3 years 3+ years Under 35 Case 2 Control 55 42 12 35-44 Case 13 Control 127 27 30 Case 12 45+ 3 Control 129 18 23