The impact of health literacy on psychosocial and behavioural outcomes among people at low risk of cardiovascular disease.

This study aimed to explore the impact of health literacy on psychosocial and behavioural outcomes for people who were not at high risk of cardiovascular disease receiving a hypothetical blood pressure reading of 135/85 mmHg. We performed a secondary analysis of data from a national sample of Australians aged 40 to 50 years (n = 1318) recruited online. Health literacy was measured using the validated Newest Vital Sign (inadequate: 0-3; adequate: 4-6). Analysed outcomes included: willingness to increase exercise and accept medication; perceived severity; positive and negative affect; illness perceptions and impacts on life and motivation. Participants with inadequate levels of health literacy perceived a blood pressure reading of 135/85 mmHg to be less serious compared to individuals with adequate health literacy (Mean Difference [MD]:0.21; 95%CI 0.03-0.39; p = .024; d = 0.13), and reported less motivation to eat well (MD:0.44; 95%CI 0.31-0.58; p < .001; d = 0.38) and exercise (MD:0.43; 95%CI 0.31-0.58; p < .001; d = 0.36). However, they were more willing to accept medication (MD:0.20; 95%CI 0.07-0.34; p = .004; d = 0.17). Participants with inadequate health literacy also perceived the condition to have fewer negative impacts on aspects of life and work than individuals with adequate health literacy, but reported greater negative emotion and more negative illness perceptions (all p < .001). Tailored communication and behaviour change support may be needed when communicating blood pressure information to people with lower health literacy and not at high risk of cardiovascular disease given the differential impacts on medication (increased willingness) and healthy exercise and diet behaviours (decreased willingness) observed in this study.

Benefits and Harms of Hypertension and High-Normal Labels: A Randomized Experiment.

BACKGROUND: Recent US guidelines lowered the threshold for diagnosing hypertension while other international guidelines use alternative/no labels for the same group (blood pressure [BP], <140/90 mm Hg). We investigated potential benefits and harms of hypertension and high-normal BP labels, compared with control, among people at lower risk of cardiovascular disease. METHODS: We conducted a randomized experiment using a national sample of Australians (n=1318) 40 to 50 years of age recruited from an online panel. Participants were randomized to 1 of 3 hypothetical scenarios where a general practitioner told them they had a BP reading of 135/85 mm Hg, using either hypertension/high-normal BP/control (general BP description) labels. Participants were then randomized to receive an additional absolute risk description or nothing. Primary outcomes were willingness to change diet and worry. Secondary outcomes included exercise/medication intentions, risk perceptions, and other psychosocial outcomes. RESULTS: There was no difference in willingness to change diet across label groups (P=0.22). The hypertension label (mean difference [MD], 0.74 [95% CI, 0.41-1.06]; P<0.001) and high-normal BP label (MD, 0.45 [95% CI, 0.12-0.78]; P=0.008) had increased worry about cardiovascular disease risk compared with control. There was no evidence that either label increased willingness to exercise (P=0.80). However, the hypertension (MD, 0.20 [95% CI, 0.04-0.36]; P=0.014), but not high-normal label (MD, 0.06 [95% CI, -0.10 to 0.21]; P=0.49), increased willingness to accept BP-lowering medication compared with control. Psychosocial differences including lower control, higher risk perceptions, and more negative affect were found for the hypertension and high-normal labels compared with control. Providing absolute risk information decreased willingness to change diet (MD, 0.25 [95% CI, 0.10-0.41]; P=0.001) and increase exercise (MD, 0.28 [95% CI, 0.11-0.45]; P=0.001) in the hypertension group. CONCLUSIONS: Neither hypertension nor high-normal labels motivated participants to change their diet or exercise more than control, but both labels had adverse psychosocial outcomes. Labeling people with systolic BP of 130 to 140 mm Hg, who are otherwise at low risk of cardiovascular disease, may cause harms that outweigh benefit. Registration: URL: http://www.anzctr.org.au/; Unique identifier: ACTRN12618001700224.