Construction of the secondary care administrative records frailty (SCARF) index and validation on older women with operable invasive breast cancer in England and Wales: a cohort st... oleh David A Cromwell, Thompson Robinson, Yasmin Jauhari, Melissa Ruth Gannon, Kieran Horgan, Karen Clements, Jibby Medina, Carmen Tsang, Sarah Shuk-Kay Tang, Ruth Pettengell