In late 2008 was published for the first time a full report on the 2003 study which included investigation of health literacy in the USA. Three types of task were used to measure health literacy: Clinical tasks (e.g. involving medication; Preventive tasks (selfcare, healthy habits etc.); Navigation tasks (negotiating your way round the health system - which in the USA includes more stuff to do with health insureance).
White, S. (2008) Assessing the Nation’s Health Literacy: Key concepts and findings of the National Assessment of Adult Literacy (NAAL). National Center for Education Statistics. http://www.ama-assn.org/ama1/pub/upload/mm/367/hl_report_2008.pdf
I found out about this from: http://healthliteracy-forhealthandwellbeing.blogspot.com/