Bridging primary care with artificial intelligence: toward a global 1.5-Tier Healthcare System.

Artificial intelligence is increasingly applied in primary care, yet systematic frameworks linking individual applications to health-system improvement remain lacking. This perspective proposes a "1.5-Tier Healthcare System," in which AI forms an intermediary layer between primary and specialist care, strengthening its four core functions: first contact, comprehensiveness, coordination, and continuity. Adaptable across high-income, resource-limited, and crisis settings, it offers a scalable alternative to concierge medicine: "concierge care for all."