In healthy individuals, elevated blood pressure is associated with diminished acute pain sensitivity. These cardiovascular/pain regulatory system interactions appear altered in patients with chronic pain; elevated blood pressure is associated with increased acute and chronic pain responsiveness. If these alterations reflect failure of overlapping systems modulating pain and blood pressure, it was expected that prevalence of clinical hypertension would be increased in the chronic pain population.
A retrospective review was conducted on randomly selected records of 300 patients with chronic pain (Pain) evaluated at a tertiary care pain center and 300 nonpain internal medicine (Medicine) patients seen at the same institution.
Results revealed that 39% of the Pain group was diagnosed with clinical hypertension, compared with 21% of the Medicine group (P < 0.001). Analyses by sex revealed similar group differences in males (P < 0.05) and females (P < 0.001), although the difference in females was double in magnitude compared with males. In contrast to more frequent male hypertension in the general population and the Medicine sample, females were more often diagnosed with hypertension (41.2%) than males (35.6%) in the Pain group. Similar group differences were obtained for antihypertensive use (P < 0.001). Stepwise logistic regression in the Pain group revealed that chronic pain intensity was a significant predictor of hypertensive status independent of the effects of age, race/ethnicity, and parental hypertension (P < 0.05).
These results suggest that chronic pain may be associated with increased risk of hypertension. Factors that may underlie this association are discussed.