OBJECTIVES

Hypertension is estimated to cause approximately 7.5 million deaths worldwide annually and reducing salt intake is vital for preventing hypertension.

The aim of this study is to evaluate the impact of positive and negative frame information about salt intake for hypertensive and non-hypertensive participants.

METHODS

A discrete choice experiment for lunch box selection was employed. An Internet survey was conducted in Japan.

Participants were 5,116 people (2,425 hypertensive and 2,691 non-hypertensive; response rate = 57.5%; 50% men).

The method was before and after the study. The information on damage of hypertension and the relationship between hypertension and salt intake was provided between the first 12 choice sets and the second 12 choice sets.

We estimated participants’ preferences for reduced-salt lunch boxes after receiving positive and negative frame information and the difference in marginal willingness to pay (MWTP) for reduced salt between pre- and post-information.

RESULTS

Both groups preferred less-expensive, lower-calorie, and reduced-salt lunch boxes. Hypertensive participants’ MWTP for reduced-salt foods significantly increased—from 102 JPY (95% confidence interval (CI), 93 to 113 JPY) to 202 JPY (95% CI, 184 to 223 JPY) and 99 JPY (95% CI, 90 to 110 JPY) to 166 JPY (95% CI, 150 to 184 JPY)—after positive and negative frame information, respectively. Further, non-hypertensive participants’ MWTP significantly increased—from 66 JPY (95% CI, 60 to 73 JPY) to 141 JPY (95% CI, 125 to 160 JPY) and 64 JPY (58 to 70 JPY) to 121 JPY (112 to 131 JPY)—after positive and negative frame information, respectively. Positive frame information induced significantly higher MWTP than did negative frame information for both non- and hypertensive participants (P < 0.001).

CONCLUSIONS

Positive frame information led to a higher MWTP for reduced-salt lunch boxes; thus, doctors should provide patients with positive frame information, which may also be useful for hypertension-prevention awareness campaigns.