CIRCADIAN BLOOD PRESSURE PROFILE IN RELATION TO LOW BACK PAIN DISABILITY INDEX

Abstract

Objective: Cross-sectional observations within population cohorts have linked low back pain with hypertension in men, but not in women. The aim of the current study was to analyze 24-hour blood pressure profile in hypertensive men and women reporting low back pain. Design and method: The study group included 85 hypertensive patients (29 M/56 F, mean age 60.6 +/- 8.3 years) with episodes of low back pain during 3 weeks before examination. All patients received antihypertensive medications in the scheme of combination therapy and none of them was on chronic painkillers. Standardized questionnaire was used to collect information on life style factors. Twenty-four hour blood pressure monitoring was provided (Spacelabs 90207) and values of 24h, daytime and nighttime blood pressure were calculated, as well as nighttime blood pressure dipping. Oswestry Low Back Pain Disability Questionnaire was used to calculate disability index. Multivariable regression was used to asses the association between blood pressure an disability index, while accounting for covariates. Results: In the whole study population, no association was found between disability index and 24-hour systolic (parameter estimate: -0.053 +/- 0.23 mm Hg per 1 point increase in disability index, p = 0.86) or diastolic blood pressure (-0.018 +/ 0.14 mm Hg per 1 point increase, p = 0.90). When analyzing men and women separately, we observed in women increased daytime diastolic blood pressure with increasing disability index (+0.29 +/- 0.16 mm Hg, p = 0.044), that resulted in more prominent day-night difference with increasing disability index (+0.42 +/- 0.14% per 1 point increase in disability index). Blood pressure values over 24 hours or nighttime blood pressure was not associated with disability index. None of associations between blood pressure values and low back pain disability index were not found in men. Conclusions: Low back pain, as assessed by standardized questionnaire of disability index, is associated with elevated daytime blood pressure in hypertensive women, that might lead to more difficulties in achieving target blood pressure in this group of patients.