Doctors rarely understand how influence really works. The result: an NHS bowing to the needs of big pharma | Margaret McCartney

Money also flows into the NHS, often in the half light. Take screening for atrial fibrillation (AF), an irregular heartbeat that can lead to strokes. There is no controversy about checking for it in people with, say, palpitations or breathlessness. But testing people who have no symptoms is quite different. It may help, or it could be harmful, leading to overuse of drugs to control heart rhythm in patients who might not need it. Quite rightly, a large trial is being run to find out.