Examining the effectiveness of zinc treatment in children admitted with diarrhoea in Kenya’s public hospitals: an observational comparative effectiveness study by Malla, L, Perera-Salazar, R, Akech, S, Ogero, M, Julius, T, Irimu, G, English, M, Thuranira, L, Ochieng, G, Kigen, B, Musabi, M, Inginia, R, Kamunya, A, Otido, S, Kuria, M, Mithamo, A, Muturi, C, Emadau, C, Mutiso, C, Kimutai, D, Mutai, L, Aduro, N, NgAr, S, Kanyingi, F, CIN author group