Easton et al. BMC Public Health 2010, 10:459 http://www.biomedcentral.com/1471-2458/10/459 appearing in the citations from the database searches. Exclusions at full text appraisal stage were largely due to studies not meeting our criteria for age or ability to speak the dominant language. The 11 studies identified from the initial reviews were also identified by the second stage search. The 2400 citations from the second stage search yielded an addi- tional 13 studies that met our inclusion criteria. The twenty-four papers that were included reported mainly on studies conducted in the USA (two were from the UK and one from Canada) (Additional File 2, Table S2). Studies used diverse methods to investigate the implications of functional or health literacy for var- ious health-related issues in a range of health care con- texts. The health related issues that the twenty-four papers considered were grouped into one or more of five outcome categories reflecting the five areas of inter- est in the review questions. An additional category of ‘emotional responses’ that it seemed inappropriate to treat simply as examples of (end state) health status emerged during the process and has been included (Additional file 2, Table S2). Three measures of health literacy (REALM, TOFHLA and s-TOFHLA) and two measures of functional literacy (NART and the Test of Basic Adult Education) were used across the 24 papers included in the review (Addi- tional file 2, Table S2). Implementation of the measures and cut-off points to determine low health literacy dif- fered even when the same measure was used. (Addi- tional file 2, Table S2). All but three papers [21-23] considered potentially confounding demographic factors in their analysis. Only two papers [24,25] clearly reported that the person who assessed health data was blinded to study participants’ health literacy status. We now summarise the key find- ings relating to each of the five health-related outcome domains. Relationship between functional or health literacy and health status There is some evidence from 3 cross-sectional studies that lower functional or health literacy is associated with poorer health status, assessed by self-report or more objectively [26-28]. Studies of 1892 emergency department walk-in patients and of 339 people living with HIV-AIDS both found that those with lower health literacy were signifi- cantly more likely to self-report their health as poor [26,27]. In the study of people with HIV-AIDS, recorded CD4 cell counts and undetectable viral loads in the medical notes confirmed the poorer health status of those with lower health literacy [27]. Both studies used the TOFHLA to measure health literacy but compared different cut-off points: Baker et al. [26] compared the Page 4 of 10 highest and lowest of three health literacy levels (0-59 vs. 75-100) while Kalichman et al. [27] compared those above and below 80% correct. A third study measured reading level using the Test of Basic Adult Education in 193 adult learners. Those with very low reading levels (at or below 4th grade), had sig- nificantly lower scores on the physical and psychosocial domains of the Sickness Impact Profile than those with higher (5th grade+) reading levels [28]. This study used an objective measure of health but focused on a group of people who were motivated to address their literacy difficulties and so were not necessarily representative of the general population with low literacy. People who have sought help with literacy may be more likely to let health professionals know they have difficulty with read- ing and writing. Psychosocial health impairment may be more prevalent in those who do not seek help with lit- eracy education and so may be underestimated by this study. Relationship between functional or health literacy and health promoting or health risk behaviours Five studies were found to have investigated the rela- tionships between health literacy levels and preventive health or health risk behaviours [22,29-32]. All used the REALM to measure health literacy but no two used the same levels for comparison. Findings from these studies were complex and mixed. Two studies found some higher health risk behaviours in those with lower health literacy but also some poten- tially conflicting evidence [22,29]. In a US study of 130 women referred for colposcopy after abnormal pap smear, those with higher health literacy reported a greater number of risk factors for cervical cancer. Differ- ences for individual risk factors varied; those with higher health literacy were more likely to report oral contra- ceptive use and having had 5 or more sexual partners in total while those with lower health literacy had higher parity. Health literacy was not associated with inter- course aged ≤18 years or with history of sexually trans- mitted disease other than HPV [29]. One UK study of 505 family planning clinic users, found that women with lower health literacy were: more likely to have been aged under 16 at first sexual intercourse; less likely to have used contraception at that time; and more likely to have had two or more partners in the previous 6 months [22]. The UK study of family planning clinic users found no significant difference across health lit- eracy levels in planned or unplanned pregnancies, previous use of emergency hormonal contraception or number of sexual partners in the previous four weeks [22]. Comparison of these two studies is difficult because they categorised health literacy levels differently.