Salt intake and risk of disaster hypertension among evacuees in a shelter after the great East Japan Earthquake

This study investigated the association between salt intake and risk of disaster hypertension. We analyzed the data of surveys evaluating the health condition of evacuees in shelters after the Great East Japan Earthquake on April 30 and May 5, 2011. Among 272 subjects who completed the basic health condition questionnaire and underwent a medical examination, 158 (58%) had disaster hypertension (systolic blood pressure ≥140 mm Hg or diastolic blood pressure ≥90 mm Hg). Average estimated sodium intake assessed by spot urine was significantly associated with disaster hypertension (odds ratio per 1 g/d, 1.16; 95% CI, 1.05-1.30). When we defined the high risk factors for salt-sensitive hypertension as older age (≥65 years), obesity (body mass index, ≥25 kg/m²), chronic kidney disease, and diabetes mellitus, estimated sodium intake was found to be a risk factor for disaster hypertension in the total group (odds ratio per 1 g/d, 1.27; 95% CI, 1.12-1.43) and even in the group without prevalent hypertension before disaster (n=146; odds ratio per 1 g/d, 1.46; 95% CI, 1.19-1.79). There was an interaction between estimated sodium intake and disaster hypertension according to the presence or absence of high risk of salt-sensitive hypertension in the group without prevalent hypertension (P=0.03). Disaster hypertension conferred a risk of microalbuminuria (odds ratio, 3.00; 95% CI, 1.71-5.26; P<0.001). We conclude that increased estimated sodium intake was associated with disaster hypertension in evacuees after disaster. This association was noted in the population with high risk of salt-sensitive hypertension and without prevalent hypertension before natural disaster. Additionally, disaster hypertension was associated with subclinical organ damage.