Reproducibility of blood pressure response to the cold pressor test: the GenSalt Study

Abstract

An elevated blood pressure (BP) response to the cold pressor test (CPT) is associated with increased risk of hypertension and cardiovascular disease. However, it is still unclear whether BP response to the CPT is a stable and reproducible trait over time. Using the same study protocol, the authors repeated the CPT 4.5 years after initial administration among 568 Han Chinese in rural northern China (2003-2005 and 2008-2009). BP was measured using a standard mercury sphygmomanometer prior to and 0, 1, 2, and 4 minutes after the participants immersed their hand in ice water (3°C-5°C) for 1 minute. Absolute BP levels and BP responses during the CPT in the initial and repeated administrations were highly correlated. For example, the correlation coefficients were 0.67, 0.73, 0.71, and 0.72 for absolute systolic BP levels at 0, 1, 2, and 4 minutes after ice-water immersion (all P 's < 0.0001). The correlation coefficients for systolic BP response were 0.41 at 0 minutes, 0.37 at 1 minute, 0.42 for maximum response, and 0.39 for the area under the curve during CPT (all P 's < 0.0001). These data indicate that BP response to the CPT is a long-term reproducible and stable characteristic in the general population.

Figure 1.

Levels of A) systolic blood pressure (SBP) and B) diastolic blood pressure (DBP) during the cold pressor test (CPT) in initial and follow-up studies, Genetic Epidemiology Network of Salt Sensitivity (GenSalt) Study, China, 2003–2005 and 2008–2009. (BP, blood pressure).

Figure 2.

Scatterplots of systolic blood pressure (top) and diastolic blood pressure (bottom) responses to the cold pressor test in initial and follow-up studies, Genetic Epidemiology Network of Salt Sensitivity (GenSalt) Study, China, 2003–2005 and 2008–2009. Sections A and E show response at 0 minutes; sections B and F show response at 1 minute; sections C and G show maximum response; and sections D and H show the total area under the curve (AUC) above baseline. All P values for correlation coefficients (r ) were less than 0.0001. Shaded areas show the 95% confidence intervals for mean predicted values.

Figure 3.

Bland-Altman plots of systolic blood pressure (top) and diastolic blood pressure (bottom) responses to the cold pressor test in initial and follow-up studies, Genetic Epidemiology Network of Salt Sensitivity (GenSalt) Study, China, 2003–2005 and 2008–2009. Sections A and E show response at 0 minutes; sections B and F show response at 1 minute; sections C and G show maximum response; and sections D and H show the total area under the curve (AUC) above baseline. The x axis represents the mean of 2 measurements from the initial study and the follow-up study, and the y axis represents the difference between those measurements from the initial study and the follow-up study. The middle line represents the mean difference and the upper and lower lines represent the limits of agreement (mean ± 2 standard deviations), respectively.