How did New Zealand's regional District Health Board groupings work to improve service integration and health outcomes: a realist evaluation.

The complexity of DHB regional working meant that success hinged on building relationships, leadership and trust, alongside robust planning and process mechanisms. As NZ reorients its health system towards a more centralised model underpinned by collaborations between local providers, our findings point to a need to align policy expectations and foster environments that support connection and collegiality across the health system.