Our systematic review update confirms that lower health literacy as measured by poorer reading skills is associated with a range of adverse health outcomes. Evidence is beginning to emerge concerning the relationship between poorer numeracy skills and health outcomes but the evidence is still too weak to be confident of an association. We found no evidence evaluating oral (verbal) health literacy and health outcomes.

Rigorous, well-designed studies of interventions to mitigate the effects of low health literacy have been conducted since our earlier review. Future studies isolating one measurable and replicable component of an intervention will, however, be particularly helpful in building this body of evidence. Many studies have now been conducted with a variety of clinic populations. Future research could enhance our confidence in the more universal applicability of results by including more broadly based and representative samples.

Table 62. Health outcome study results (KQ1): summary and comparison of 2004 and 2010 systematic reviews

Table 63. Numeracy outcome study results (KQ 1): summary of 2010 systematic review

Table 64. Results of intervention studies with single design strategies (KQ 2): summary and comparison of 2004 and 2010 systematic reviews

Table 65. Results of interventions with multiple design strategies: summary and comparison of 2004 and 2010 systematic reviews