Collaborative care for the detection and management of depression among adults with hypertension in South Africa: study protocol for the PRIME-SA randomised controlled trial oleh Inge Petersen, Arvin Bhana, Naomi Folb, Graham Thornicroft, Babalwa Zani, One Selohilwe, Ruwayda Petrus, Ntokozo Mntambo, Daniella Georgeu-Pepper, Tasneem Kathree, Crick Lund, Carl Lombard, Max Bachmann, Thomas Gaziano, Naomi Levitt, Lara Fairall, on behalf of the PRIME-SA research team