Long-term conditions account for most healthcare use across working-age and older adult populations, yet care remains fragmented across providers, pathways, and specialties. This talk will describe a population health approach to multimorbidity developed across North Central London, integrating primary care, secondary care, community services, and linked healthcare data. The central premise is that fragmented healthcare is has parallels to problematic polypharmacy: just as prescribing cascades emerge when no one has oversight of the whole medication burden, so to can poorly coordinated care generate cascades of referrals, investigations, follow-up appointments, and specialist involvement without anyone retaining a coherent view of the overall patient journey. We will discuss an alternative approach in which general physicians work alongside primary care teams to rationalise healthcare activity, improve coordination, and identify unmet need earlier across the wider healthcare economy.