Blood pressure readings were also sent through a modem to the research team. If blood pressure readings exceeded or fell below certain safety thresholds and the patients hadn't checked up with their regular doctor, they were contacted by researchers by telephone. This only happened in 3 percent of cases, according to the authors.

By the end of the study, mean systolic blood pressure declined nearly 50 percent more for self-monitoring patients than for controls.


For self-monitoring patients, systolic blood pressure dropped around 13 mm Hg on average after half a year and by nearly 18 mm HG after a full year. By comparison, the control group saw blood pressure drop by around 9 mm Hg on average after six months and only 12.2 mm Hg on average after one year. For those watching and tweaking their medication schedules, they had 3.7 mm Hg lower systolic blood pressure halfway through the study and 5.4 mm Hg lower, on average, at the end.

Diastolic blood pressure changes were, overall, not significant, the authors said, possibly because more patients were needed to detect the changes.

The researchers believe the difference in the drop in systolic blood pressure is likely explained by increased use of medications, such as calcium antagonists and thiazides. Of the patients who self-monitored until the end of the study, nearly 70 percent got at least one medication change, and they tended to use slightly more antihypertensive drugs by the program's finish.

Still, the resulting change in medication did have one unpleasant side effect. Although side effect frequencies were basically the same in both groups, self-monitoring patients reported slightly more leg swelling - around 32 percent versus 22 percent of controls - possibly because of increased use of calcium antagonist drugs, the authors said.

And many questions about the technology remain.

Although the authors are conducting an analysis to see whether the increased cost of providing patients with self-monitoring technology was offset by savings elsewhere - say, by preventing high blood pressure-related disease - they said they will publish the results separately.

"[T]his will be a separate paper, probably in the autumn," McManus told DOTmed news by email. "We're still doing the analysis."

And the authors admit, self-monitoring won't work for everybody. For instance, patients taking more than two drugs, and those with dementia or memory troubles, were excluded from the study. Less affluent patients also experienced less of a benefit from self-monitoring.

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