Differences in blood pressure measurements between arms are commonly encountered in clinical practice. If such differences
are not excluded they can delay the diagnosis of hypertension and can lead to poorer control of blood pressure levels. Differences in
blood pressure measurements between arms are associated cross sectionally with other signs of vascular disease such as peripheral arterial
disease or cerebrovascular disease. Differences are also associated prospectively with increased cardiovascular mortality and morbidity
and all cause mortality. Numbers of publications on inter-arm difference are rising year on year, indicating a growing interest in the
The prevalence of an inter-arm difference varies widely between reports, and is correlated with the underlying cardiovascular risk of the
population studied. Prevalence is also sensitive to the method of measurement used.
This review discusses the prevalence of an inter-arm difference in different populations and addresses current best practice for the detection
and the measurement of a difference. The evidence for clinical and for vascular associations of an inter-arm difference is presented in
considering the emerging role of an inter-arm blood pressure difference as a novel risk factor for increased cardiovascular morbidity and
mortality. Competing aetiological explanations for an inter-arm difference are explored, and gaps in our current understanding of this
sign, along with areas in need of further research, are considered.