Data on screening up to and including round five are now complete, but women with the earliest dates of entry will have six or more rounds.
Observation time was calculated from the entry date to an exit date, which was defined as the earliest date of recorded fracture, date of death, date of deregistration with the practice, date of last upload of computerised data, or the study end date (30 June 2008).
We censored patients at the earliest date of a diagnosis of venous thromboembolism, death, deregistration with the practice, last upload of computerised data, five years after study entry, or the study end date (30 April 2010).
We censored patients at the earliest date of the first upper gastrointestinal haemorrhage or intracranial haemorrhage, death, deregistration with the practice, last upload of computerised data, three months after their last prescription for anticoagulants (if applicable), five years after their study entry date, or the study end date (1 October 2013).
Each member of the cohort accumulated person-years of follow-up from the date of entry until the earliest date among those of outcome onset (hospital admission for UGIC) or censoring (death, emigration or 31 December 2007).
Follow-up extended from date of entry into the SCCS until the earlier of 28 February 2011 (2 months prior to the most recent SSA linkage) or date of death.
The date of entry into care was defined as that of the earliest record found in any of the data sources.
Woman-years for analysis of all-cause mortality are calculated from each woman's date of entry to date of death or 31st March 2002, whichever is earlier.
Those for analyses of incidence are calculated from the date of entry to the date of death or 31st December 1999, whichever is earlier, and are also censored at the date of diagnosis of breast cancer.
