Loss of population data sources when health systems are not responsible for geographically defined populations: implications of the Health and Social Care Act of 2012 in England.

Biomedical health services and health systems research require timely, complete, accurate and accessible data relating to geographical populations in order to facilitate needs assessment and planning of medical care, new medicines and technology. The international trend towards competition and privatisation has largely proceeded as if data generation were immune to market fragmentation and loss of universal coverage. By examining recent reforms to the English National Health Service, the authors show that this is not the case. Routine and population data are products of administrative systems and the nature, completeness and quality of data available to clinical and public health researchers are substantially impaired by market reforms.