Blood Pressure and Blood Pressure Variability in Relation to Chronic Low Back Pain Among Patients with Hypertension.

Background: Chronic pain which tends to be localised particularly in the lower back and lower extremities is one of the risk factors for elevated blood pressure (BP). In this cross-sectional study, we evaluated whether chronic low back pain (cLBP) is associated with BP variability, which may be related to increased mortality and morbidity.

Methods: We included 85 consecutive hypertensive patients with a median age of 62 years (IQR, 55-67) with cLBP, for which intensity was assessed using the Oswestry Disability Index (ODI). Ambulatory blood pressure monitoring (ABPM) was performed to evaluate the values and variability of systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) over 24 h, day- and nighttime BP variability assessed as BP standard deviation (SD).

Results: In the whole study population, the median ODI questionnaire score was 16 (IQR, 11-20). Patients with an equal/higher than median ODI score had lower nighttime DBP compared with other patients (p = 0.028). Equal/higher than median ODI score correlated with 24 h SD values for SBP and MAP (r = 0.263; p = 0.016, and r = 0.229; p = 0.036, respectively), as well as with day-night differences in SBP (r = 0.229; p = 0.035), DBP (r = 0.253; p = 0.019), and MAP (r = 0.263; p = 0.015). We performed a multivariate regression analysis adjusted for potential confounders, and equal/higher than median ODI score was predicted by age (OR, 1.07; 95% CI, 1.006-1.14; p = 0.031) and day-night DBP difference (OR 1.07; 95% CI 1.002-1.15; p = 0.044).

Conclusions: To our knowledge, this is the first study to show that more intense cLBP is associated with BP variability among patients with hypertension.