Hypertension risk in CSU 2023

Stimulated by Chang et al 2023.[1]

CSU – chronic spontaneous urticaria
CIU – chronic idiopathic urticaria (same as CSU)
NHIRD – National Health Insurance Research Database
LHID – Longitudinal Health Insurance Database
aHR – adjusted hazard ratio

key to acronyms

This is another of the large retrospective observational cohort studies from Taiwan. It starts by introducing an unexpected association for me (again) – the increased risk of hypertension in patients with CSU. The increased risk associated with CSU has been estimated using the same type of observation research from the Taiwanese NHIRD, or more specifically the LHID 2000 subset of the NHIRD.[2] The increased risk is 1.37 or 37%, so not huge numerically, but clearly important in public health terms on a population basis, especially given the sequelae of hypertension.

Chang and colleagues found 43 547 patients with CSU who had acupuncture between the start of 2008 and the end of 2019 and matched them with 43 547 patients, also with CSU, who had not had acupuncture. It does not seem as though the acupuncture had to be for the CSU or that there needed to be a minimum number of sessions to qualify, but I guess that neither matters nor favours acupuncture use in terms of the results here.

Acupuncture use was associated with a reduced incidence of hypertension – aHR 0.56 ie a 44% risk reduction, which is slightly more than the increased risk of hypertension in patients with CSU. The lowest aHR in the multivariate analysis was for the drug fexofenadine at 0.32 and in a different analysis (an interaction analysis) the combination of acupuncture and drugs had the lowest aHR at 0.10.

In this interaction analysis the drugs alone were associated with a risk reduction of nearly 80% (aHR 0.21).

I am struggling to work out how taking antihistamines could reduce the risk of developing hypertension to such a degree. The ~50% risk reduction associated with acupuncture is now familiar to us from all the other large retrospective observational cohorts (see Retrospective cohorts), but an ~80% risk reduction associated with antihistamines seems difficult to fathom, particularly as this seems to imply that the drugs may reduce the risk twice as much as the increased risk with CSU.

Perhaps taking antihistamines reduces our general irritation with the world at large and we should all be taking some ;-).

References

1          Chang H-W, Lin W-D, Shih P-J, et al. Acupuncture Decreases Risk of Hypertension in Patients with Chronic Spontaneous Urticaria in Taiwan: A Nationwide Study. Healthc Basel Switz 2023;11:1510. doi:10.3390/healthcare11101510

2          Chang H-W, Cheng H-M, Yen H-R, et al. Association between chronic idiopathic urticaria and hypertension: A population-based retrospective cohort study. Ann Allergy Asthma Immunol Off Publ Am Coll Allergy Asthma Immunol 2016;116:554–8. doi:10.1016/j.anai.2016.04.001

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Declaration of interests MC