[Associations between hypertensive snowbirds' length of migratory stay and blood pressure control]

Objective: To explore the relationship between the hypertensive snowbirds' length of migratory stay and their blood pressure control and blood pressure levels. Methods: This study was a cross-sectional study. A population of snowbirds with hypertension was recruited between October and November 2022, and a structured questionnaire was used to collect their self-measured blood pressure and length of stay in Hainan Province. The blood pressure control status is determined based on self-measured blood pressure. According to the self-measured blood pressure to determine whether the blood pressure was well controlled. The associations between snowbirds' length of stay and their blood pressure control as well as their self-measured blood pressure were analyzed using restricted cubic splines. Results: A total of 362 research subjects were included, 169(46.7%) of whom were male, and their age was (69.7±7.0) years old. The participants' self-measured systolic blood pressure and diastolic blood pressure were (129.1±16.2) mmHg (1 mmHg=0.133 kPa) and (78.9±10.1) mmHg, respectively. Overall, 174 (48.1%) participants attained adequate blood pressure control. The median length of stay in Wuzhishan City was 7(6, 7) months. There was an inverted U-shaped association between snowbirds' length of stay and blood pressure control (overall: P=0.023; nonlinearity: P=0.014), where participants with a length of stay of 7 months had the highest rate of blood pressure control. There is a U-shaped curve relationship between length of stay and systolic blood pressure (overall: P=0.001; nonlinearity: P=0.033), and a linear negative correlation with diastolic blood pressure (β=-1.19, P=0.003). Conclusions: Compared with hypertensive snowbirds with too long or too short lengths of stay, snowbirds who stayed in Wuzhishan City for seven months have better blood pressure control, and systolic blood pressure is also lower.