Hearing a human say blood-thinner doses are correct may be reassuring, but an automated system can be equally effective for some, a new study suggests.

In Monday's online issue of the Canadian Medical Association Journal, researchers concluded that an automated voice response system reduced the workload by 33 per cent and was almost as effective as a phone call from a human.

About five per cent of seniors take oral anticoagulants such as warfarin for blood clotting disorders. Patients need to take regular blood tests to make sure they're taking the right dose — too little doesn't work, and too much can cause serious bleeding problems including a deadly form of stroke.

The dose has to be individualized and monitored closely, said study author Dr. Alan Forster, a patient safety expert with the Ottawa Hospital Research Institute and the University of Ottawa.

The study was designed to test whether computer algorithms can predict the right dose better than a human.

"The interactive voice response system was effective in communicating complex information as 77.8 per cent of messages were successfully delivered and did not require input from staff," Forster and his coauthors wrote.

'You know they care'

A pharmacist checks everything before an automated call is made to the patient, and contacted patients when dosage messages were unsuccessful.

"It works well in these patients who are well controlled," Forster said. "It frees up time to look after the patients who are not in good control. The people who are not in good control are the people that the computer is not going to be good at looking after anyway."

In the study, 226 patients received their dosing information without direct human contact. They were all stable in terms of the anticoagulation control, spoke English, did not having hearing problems and 80 per cent had been taking warfarin for more than one year.

"You feel good because you know they care," said Dianna Siteman, 65, of Navan, Ont., near Ottawa, one of the patients who participated in the study. "Even if you're talking to 'not a human.'" Siteman said the automated system of phone calls, appointment reminders and blood test results gave her confidence.

Given that managing warfarin therapy is expensive and labour-intensive, "any technology-based intervention that could improve the quality and efficiency of anticoagulation care, while reducing costs, would be extremely attractive," said Dr. Jerry Gurwitz of the University of Massachusetts Medical School in a related commentary.

With files from Canadian Press