Low health literacy is associated with less knowledge of chronic diseases, poorer mental and physical health, limited use of preventive services, and higher rates of admissions to hospital.
A team of researchers at University College London set out to investigate the relationship between health literacy and mortality in older adults in England, irrespective of known risk factors like age, socio-economic position and pre-existing illness.
The study involved 7,857 adults aged 52 years and over who took part in the second wave (2004-5) of the English Longitudinal Study of Ageing (ELSA). Participants completed a test of functional health literacy, which assessed understanding of written instructions for taking an aspirin tablet. Deaths were monitored until October 2009.
A total of 621 deaths occurred during follow up: 321 in the high-test score group, 143 in the medium group and 157 in the low group.
One in three adults was unable to completely understand the medicine label instructions, indicating limited health literacy.
Adults with the lowest health literacy scores were more than twice as likely to die within five years as those with the highest scores.
Differences in age, socio-economic position, and general health at the start of the study accounted for less than half of the increased risk.
Even after adjusting for measures of cognitive (mental) function, low health literacy was still a significant predictor of mortality.
This study suggested that a third of older adults in England have difficulties reading and understanding basic health related written information. Those with the poorest understanding are at greatest risk of mortality, the researchers said.
The findings should remind all healthcare professionals to adopt effective communication techniques for patients with low health literacy, they concluded.
At a broader level, the design and delivery of health related services for older adults in England "should be sensitive to the limited health literacy capabilities within this population."
The study was published on bmj.com.