Factors associated with visit-to-visit variability of blood pressure in hypertensive patients at a Primary Health Care Service, Tabanan, Bali, Indonesia

Background: An increasing number of valid and well-designed trials have demonstrated a positive correlation between visit-to-visit variability (VVV) in systolic blood pressure (SBP) and increased risk of stroke and coronary heart disease among hypertensive patients.

Methods: A cross-sectional study was conducted that involved 74 patients who visited the outpatient clinic at the Tabanan III Primary Health Care Service during April to May 2017. Blood pressure was retrospectively obtained from medical records. VVV was classified as low or high on the basis of the standard deviation of SBP. Antihypertensive medication adherence was expressed as the percentage of days covered, and sodium intake was measured with 24-hour food recall. Bivariate analysis was performed, followed by multivariate analysis for significant variables.

Results: Among the participants, 67.6% were female, with a mean (standard deviation [SD]) age of 62.70 (10.00) years. Blood pressure was measured 4.82±0.78 times during the period, and the mean (SD) SBP was 139.65 (10.57) mm Hg. Nonadherence and sodium intake were significantly higher in the high-VVV group than in the low-VVV group (nonadherence 13.5% vs. 37.8%, P=0.033; sodium intake 1278.44±43.02 mg vs. 1495.85±45.26 mg, P=0.038). After adjustment for other covariates, the differences remained significant only for nonadherence (model I exp β=3.89 [95.0% confidence interval 1.23‐12.34, P<0.05], model II exp β=3.9 [95.0% confidence interval 1.12‐14.15, P<0.05]). The area under the curve was 0.636 (P<0.05), with sensitivity of 67.6% and specificity of 51.4%.

Conclusion: Nonadherence to antihypertensive medication was significantly associated with higher VVV of SBP. Further study is needed to assess whether improving adherence could reduce VVV and improve cardiovascular outcomes.