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  • br Abbreviations C consented NC non consented

    2020-08-18


    Abbreviations: C, consented; NC, non-consented; DCIS, ductal carcinoma in situ; LCIS, lobular carcinoma in situ; NHI, National Health Index number
    Corresponding author.
    E-mail address: [email protected] (J.M. Elwood).
    Table 1
    Disease specific survival up to 10 years in consented and non-consented patients, for invasive cancer and for DCI.
    Group and numbers
    Number Survival % 95% CI
    Number Survival % 95% CI
    Number Survival % 95% CI
    followed
    followed
    followed
    Difference consented to not consented
    Difference consented to total
    Difference consented to not consented
    Difference consented to total
    required. As a result of the review, the ethics committee in July 2011 allowed the registry a dispensation to research and analyse ‘non-con-sented data’ (NC) and to compare it with ‘consented data’ (C). This temporary access aimed at checking whether the NC data was com-promising or skewing the conclusions in the overall data. A short report comparing the consented and non-consented groups was prepared. (We will refer to patients as ‘consented’ rather than ‘consenting’, as consent requires the patient to be invited as well to give their consent.) Further ethical review following this report resulted in changes in the consent process: approval to use an opt-out approach in November 2012, and the grant of a waiver of consent in March 2013 allowing the previously non-consented data to be analysed and kept in the registry.
    For this study, information on all patients diagnosed from 2000 to 2012 was accessed, including data from patients not giving active consent (‘NC data’). The NC data came from those patients had not returned their consent form for any reason.
    2. Methods
    2.1. Patient selection and data collection
    The registry data are from both patients who give consent (C) and those who did not give consent (NC) within the UNC1999 2000-2012. Eligible patients are defined by registry criteria applied at that time:
    • no breast cancer history before 1st of June 2000; • diagnosed with invasive carcinoma or ductal carcinoma in situ (DCIS) but not lobular carcinoma in situ (LCIS) alone;
    • Auckland region resident at first surgery, or Auckland region re-sident who had first surgery outside Auckland and came back to Auckland for adjuvant treatment; • New Zealand permanent resident (including Cook Island resident) at the time of diagnosis.
    The registry collates information on baseline, treatment and follow-up data, including data on diagnosis and treatment of local/regional recurrence and metastatic disease, from both the public and private health care facilities to which registry data managers have been given access. These systems include all public hospitals, private hospitals and all private practitioners known to be treating breast cancer patients within the Auckland region. Mortality data is obtained by regular linkage by the Ministry of Health between the study database and na-tional mortality records using the patient’s unique National Health 
    2.2. Statistical analysis
    Consented and NC groups were compared using Kaplan Meier sur-vival analysis, chi square and log-rank tests [3]. Direct standardisation used the whole patient group as the standard population, with con-fidence limits [4]. Stata statistical software (version 13) was used for the statistical analysis [5]. A sensitivity analysis, of survival left-cen-sored at 90 days after diagnosis, thus excluding patients with less than 90 days follow-up, was done to assess the effects of bias arising from completion of the consent process being delayed up to 90 days post-diagnosis.
    3. Results
    3.1. Invasive cancer: survival by consent status
    3.2. Overall survival comparing the overall cohort and consented group (invasive)
    The overall survival rates for all patients are consistently lower than those of the subgroup who give active consent (Table 1), the differences at 2, 5 and 10 years respectively being 1.6, 2.4, and 2.4%. The survival rates based on all patients lie below the 95% confidence limits for the rates based only on the consented patients.
    Fig. 1. Invasive cancer: disease-specific survival of consented and non-consented patients, with 95% confidence bands. Logrank statistic chisq 400.1, p < 0.0001.
    Table 2
    Proportions of patients not consented, by age and ethnicity.
    Consented Non- % non 95% CL
    consented consented
    Age and ethnicity mutually standardised by direct method.
    Subjects with missing data on ethnicity excluded (6.0% of consented, 5.8% of non-consented).
    3.3. Features of consented and non-consented patients
    The group of non-consented patients with invasive cancer differs from the consented group in demographic features, disease character-istics, treatment, and survival. For demographic factors, age and eth-nicity are correlated. The proportions not consented increased regularly with age; after adjustment for ethnicity, from 8.4% at ages < = 49 to 26.5% at ages 80 and over, the differences being significant (Table 2). By ethnicity, adjusted for age, and compared to NZ European women (9.9% non-consented), the non-consented proportions was similar in Maori (9.8%), but significantly higher in Pacific women (14.4%). Asian women and those of ‘other’ ethnicities had non-significantly higher proportions than NZ Europeans.