BP variability a long-term challenge

Sep 2 2013

By Eleanor McDermid, Senior medwireNews Reporter

Blood pressure variability (BPV) over the long term predicts mortality among patients receiving treatment for hypertension, a study shows.

Data on 14,522 patients treated at a single BP clinic show that greater BPV over time frames of up to 10 years is associated with increased cardiovascular, noncardiovascular, and all-cause mortality.

Of note, Sandosh Padmanabhan (University of Glasgow, UK) and co-workers found no link between BPV and stroke mortality. However, previous studies that reported strong links between BPV and stroke assessed stroke incidence, for which the team had no data.

The researchers calculated the absolute differences between successive BP measurements, rather than using the standard deviation, thus accounting for the order of measurements. They found that the greatest BPV occurred during the first year, presumably reflecting changes in medication as doctors attempted to control and stabilize patients’ BP.

Overall, being in the fourth versus the first quartile of systolic BPV raised patients’ risk for mortality about 1.3- to 1.6-fold. This was true for cardiovascular, noncardiovascular, and all-cause mortality and was true for BPV during the first year of treatment, years 2–5, and years 5–10.

Diastolic BPV also tended to raise mortality risk, although the association was weaker than for systolic BPV and present mainly for cardiovascular mortality.

The associations were independent of baseline variables including age, gender, smoking, existing cardiovascular disease, and estimated glomerular filtration rate. They were also independent of actual BP, suggesting that BPV “probably captures a biological process different from BP regulation.”

Indeed, when patients were stratified according to systolic BP levels, the effect of BPV on mortality was similar across categories of less than 140 mmHg, 140–160 mmHg, and more than 160 mmHg. For example, normotensive patients had a nonsignificant 1.4-fold increase and a significant 1.9-fold increase in all-cause mortality risk if they were in the fourth versus first BPV quartile during year 1 and years 2–5, respectively.

Writing in Hypertension, the team concludes: “Further clinical implications depend on whether there are interventions that can change long-term visit-to-visit BPV and whether these interventions will result in improvement in outcomes.”

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