Investigating relationships between health need, primary care and social care using routine statistics.

Closer integration of primary and social care is central to the agenda of Primary Care Groups and Trusts (PCG/Ts) in England. Relationships between the need for care and primary and social care provision at local levels are investigated using routinely available statistics. Primary care provision is negatively associated with need resulting from material deprivation, but positively associated with older age-related need. Conversely, provision of social care is positively related to need resulting from deprivation but is unrelated to the size of local elderly populations. The 'inverse care law' does not capture the complexity of the relationships between need and provision. A lack of boundary coterminosity represents a serious impediment to the goal of establishing integrated health and social care systems for local populations.