Objective To investigate the dose-effect relationship between 24-hour ambulatory blood pressure and major adverse cardiovascular events (MACE) in urban and rural patients with masked hypertension (MH).

Methods A retrospective selection was conducted in individuals who completed physical examinations at the Physical Examination Center of Xingtai Central Hospital and had complete clinical data. Among them, 180 MH patients were randomly selected as case group, and 120 individuals with normal blood pressure were randomly selected as control group. The 24-hour ambulatory blood pressure parameters 24-hour systolic blood pressure (24 hSBP), 24-hour diastolic blood pressure (24 hDBP), daytime diastolic blood pressure (dDBP), daytime systolic blood pressure (dSBP), nighttime diastolic blood pressure (nDBP), and nighttime systolic blood pressure (nSBP) of the two groups were compared. According to the occurrence of MACE, patients in the case group were divided into MACE subgroup and N-MACE subgroup, and their general information and 24-hour ambulatory blood pressure were compared. Based on restricted cubic spline (RCS) analysis, the dose-effect relationship between 24-hour ambulatory blood pressure and MACE was analyzed, and the efficacy, accuracy, and clinical utility of 24-hour ambulatory blood pressure in predicting MACE were evaluated.

Results The 24 hSBP, 24 hDBP, dDBP, dSBP, nDBP, and nSBP in the case group were all higher than those in the control group, with statistically significant differences (P < 0.05). The body mass index, waist circumference, 24 hSBP, 24 hDBP, and homocysteine (Hcy) levels in patients in the MACE subgroup were all higher than those in the N-MACE subgroup, while the relative appendicular skeletal muscle mass index (RASMI) was lower than that in the N-MACE subgroup, with statistically significant differences (P < 0.05). RCS analysis showed that when 24 hSBP≥135 mmHg, an increase in its value was associated with an increased risk of MACE, while when 24 hSBP < 135 mmHg, a decrease in its value was also associated with an increased risk of MACE. When 24 hDBP≥77 mmHg, 24 hDBP was positively correlated with the risk of MACE, while when 24 hDBP < 77 mmHg, there was no significant correlation between 24 hDBP and the risk of MACE. Receiver operating characteristic curve analysis showed that the areas under the curve (AUC) for 24 hSBP, 24 hDBP alone, and their combined prediction of MACE were 0.753, 0.748 and 0.899 respectively, with the combined prediction having the largest AUC. Calibration curve and decision curve analysis showed that the combined model of 24 hSBP and 24 hDBP had good prediction accuracy and clinical net benefit.

Conclusion Abnormal 24-hour ambulatory blood pressure in urban and rural MH patients shows a non-linear dose-effect relationship with the occurrence of MACE. When 24 hSBP is ≥135 mmHg or 24 hDBP≥77 mmHg, the risk of MACE significantly increases, and the combined application of 24 hSBP and 24 hDBP has good predictive efficacy for MACE.