OBJECTIVES: Post-hoc subgroup analyses are still used in clinical trials of medical technologies to identify patient populations in whom greatest benefits can be achieved, despite this being derided as an analytical approach. Indeed, using post-hoc analyses, aspirin has been shown to be ineffective in acute myocardial infarction patients born under the star signs of Libra and Gemini (ISIS-2, 1988, Lancet) and endarterectomy is only efficacious in treating symptomatic stenosis patients born on a Monday, Wednesday, or Friday (ECST group, 1998, Lancet). This research aimed to determine whether National Institute of Health and Care Excellence (NICE) appraisal recommendations could be correlated with full moon dates through application of a post-hoc analysis. METHODS: All NICE final appraisal determinations were identified up to October 2014 from which the date and decision was extracted. Full moon dates for Manchester were extracted from www.timeanddate.com