Ambulatory blood pressure in 570 Danes aged 19-21 years: the Odense Schoolchild Study

Sources of inaccuracy in the measurement of adult patients' resting blood pressure in clinical settings: a systematic review

BACKGROUND

To interpret blood pressure (BP) data appropriately, healthcare providers need to be knowledgeable of the factors that can potentially impact the accuracy of BP measurement and contribute to variability between measurements.

METHODS

A systematic review of studies quantifying BP measurement inaccuracy. Medline and CINAHL databases were searched for empirical articles and systematic reviews published up to June 2015. Empirical articles were included if they reported a study that was relevant to the measurement of adult patients' resting BP at the upper arm in a clinical setting (e.g. ward or office); identified a specific source of inaccuracy; and quantified its effect. Reference lists and reviews were searched for additional articles.

RESULTS

A total of 328 empirical studies were included. They investigated 29 potential sources of inaccuracy, categorized as relating to the patient, device, procedure or observer. Significant directional effects were found for 27; however, for some, the effects were inconsistent in direction. Compared with true resting BP, significant effects of individual sources ranged from -23.6 to +33 mmHg SBP and -14 to +23 mmHg DBP.

CONCLUSION

A single BP value outside the expected range should be interpreted with caution and not taken as a definitive indicator of clinical deterioration. Where a measurement is abnormally high or low, further measurements should be taken and averaged. Wherever possible, BP values should be recorded graphically within ranges. This may reduce the impact of sources of inaccuracy and reduce the scope for misinterpretations based on small, likely erroneous or misleading, changes.

Age and the difference between awake ambulatory blood pressure and office blood pressure: a meta-analysis

BACKGROUND

Ambulatory blood pressure (BP) (ABP) is a better predictor of adverse cardiovascular events than office BP (OBP). Owing to the extensive literature on the 'white coat effect', it is widely believed that ABP tends to be lower than OBP, with statements to this effect in Joint National Committee VII. However, recent evidence suggests that the difference varies systematically with age.

METHODS

We searched PubMed to identify population studies, published before April 2009, which assessed OBP and either ABP or home BP (HBP). On account of significant heterogeneity in the outcomes, random effect models were used for the meta-analyses.

RESULTS

OBP increased with age more steeply than awake ABP. OBP became higher than awake systolic/diastolic ABP at the age of 51.3/42.7 years in men (13 studies, N=3562) and 51.9/42.3 years in women (11 studies, N=2585). In the data in which OBP and HBP were measured (eight studies, N=4916), OBP was higher than HBP at all ages. In the data in which OBP, awake ABP, and HBP were all measured (two studies, N=895), awake ABP was higher than HBP at younger ages, becoming similar at the older age.

CONCLUSION

OBP tends to be higher than awake ABP only after the age of 50 years for systolic and after the age of 45 years for diastolic BP, but is lower than ABP at younger ages; in contrast OBP tends to exceed HBP at all ages.