The Million Women Study

is a large prospective cohort study of women in the UK. Details of the design and methods of the study have been described elsewhere [11]. In short, 1.3 million women invited for breast cancer screening at National Health Service (NHS) clinics in England and Scotland were recruited into the study in 1996–2001 by completing a questionnaire, which included questions on anthropometry, physical activity, and other factors, and giving written Palbociclib datasheet consent to participate (see http://www.millionwomenstudy.org). Ethics approval was provided by the Oxford and Anglia Multi-Centre Research Ethics Committee. Each woman’s unique NHS identification number, together with other personal information, LBH589 was used to link to cause-specific information

on NHS hospital admission databases: Hospital Episodes Statistics for England, [12] and Scottish Morbidity Records in Scotland [13]. The databases include information both on inpatient (i.e. overnight) stays and day-case admissions (where women were admitted and discharged on the same day, e.g. for procedures such as the reduction of a fracture), but not on outpatient visits. Information on the date of diagnoses and procedures associated with each hospital admission were provided, coded to the World Health Organisation’s International Classification of Diseases, 9th and 10th revisions (ICD-9 and ICD-10) [14] for diagnoses and the Office of Population Censuses and Surveys’ classification of surgical operations and procedures, fourth revision (OPCS-4) [15] for procedures. Incident cases were defined as the first hospital record (day-case or overnight admission) of ankle fracture (824.0–824.9, ICD-9; S82.3, S82.5–S82.6, S82.8, ICD-10), of wrist fracture Thiamet G (813.4, 813.5, 814.0–814.1 ICD-9; S52.5–S52.6, S62.0–S62.1, S62.8, ICD-10), or of hip fracture (820, ICD-9; S72.0–S72.2, ICD-10) occurring

after recruitment into the study. For the purposes of censoring at the first occurrence of any fracture (see below), all other fractures were defined as codes: 800.0, 800.5, 801.0, 801.5, 802, 803.0, 803.5, 804.0 804.5, 805, 807–829 (ICD-9) and M48.4, M80, M84.3, S02, S12, S22, S32, S42, S52, S62, S72, S82, S92, T02, T08, T10, T12, T14.2, X59.0 (ICD-10). Analyses were restricted to postmenopausal women: those who reported at baseline that they had experienced natural menopause (49%), or had undergone a bilateral oophorectomy (6%) were defined as postmenopausal. Women who were premenopausal, perimenopausal, or of unknown menopausal status at recruitment, were assumed to be postmenopausal after they reached the age of 55 years, as 96% of women in this cohort with a known age at natural menopause were postmenopausal by that age.