Frailty, multimorbidity and polypharmacy: exploratory analyses of the effects of empagliflozin from the EMPA-KIDNEY trial by Mayne, KM, Sardell, R, Staplin, N, Judge, P, Zhu, D, Sammons, E, Wanner, C, Emberson, J, Preiss, D, Landray, M, Baigent, C, Haynes, R, Herrington, W