24-Hour ambulatory blood pressure and C-reactive protein: a systematic review and meta-analysis

Inflammation plays a key role in pathophysiology of hypertension; however the relevance of specific inflammatory mediators, such as C-reactive protein (CRP) is uncertain. We conducted a systematic literature review and meta-analysis to assess the associations between CRP levels and 24-hour blood pressure (BP) values in adult patients.

We performed a systematic search of PubMed/MEDLINE, Embase, Web of Science, and Scopus for human studies published between January 2013 and June 2023. We included cross-sectional and cohort studies. We excluded studies reporting clinically significant inflammation. We calculated the Pearson's correlation coefficients between 24-hour BP indices and the CRP levels weighted by the inverse of their variances.

Of 716 reports identified, 20 met eligibility criteria (10,799 participants, mean age ± standard deviation [SD] 56.1 ± 9.5 years, mean ± SD 24-hour systolic BP [SBP] 132.2 ± 14.3 mmHg, and diastolic BP [DBP] 79.3 ± 9.8 mmHg). CRP ranged from 0.14 to 10.6 mg/L, median 2.66 mg/L (interquartile range, 1.13-5.13 mg/L). In the subgroup of studies where CRP levels were ≥ 3 mg/L, a significant positive association between CRP and average 24-hour SBP (r = 0.79, P < 0.001) and DBP (r = 0.83, P < 0.001) was observed. When all studies were analyzed however, there was no correlation between CRP and neither 24-hour SBP (r = 0.18, P = 0.29), nor DBP (r = 0.27, P = 0.94).

CRP may be an important biomarker of the relationship between inflammation and hypertension. However, the relation may not be linear throughout the entire range of CRP values.

International Prospective Register of Systematic Reviews (PROSPERO) Identifier: CRD42023462606.