EDITOR—Lattimer et al report a randomised controlled trial to show the safety and effectiveness of nurse telephone consultations in out of hours primary care.1 I accept that the results showed a reduced workload for general practitioners from the nurse intervention, probably at an increased cost. For methodological reasons, however, I am less certain whether the results show safety.

Lattimer et al report that during intervention periods, 49.8% of the calls could be managed by the nurse alone without referral to a doctor. This implies that 50.2% of the calls were assessed twice: once by an experienced and specially trained nurse using a systematic assessment with the aid of decision support software and then by the general practitioner in attendance. I would expect that the improved diagnosis and management in this subgroup would lead to much better clinical outcomes than in the control group, which had only one assessment by the general practitioner. This improved outcome …