Adherence Strategies

An effective, inexpensive way to measure adherence

Telephone calls worked as well as home visits

A Connecticut research group wanted to see if they could develop a way to measure HIV medication adherence both cost-effectively and accurately.

The result is a study showing that unannounced telephone calls to HIV patients, in which patients are asked to count their pills, works economically and is very accurate.1

"We've done adherence work in the past and have a substantial problem measuring and monitoring medication adherence," says Seth Kalichman, PhD, a professor of psychology at the University of Connecticut in Storrs, CT.

"That's a theme," Kalichman adds. "A lot of researchers and clinicians have the same problem because electronic monitoring is cumbersome and has significant problems we can't get past."

One alternative was developed by a San Francisco, CA, researcher who used unannounced visits to HIV patients to count their pills. This proved very reliable.2

"The issue we faced was that because we do our research work in Atlanta, our people are very spread out," Kalichman says.

Visiting participants to count pills is an expensive method for ascertaining adherence in just about any city except San Francisco, where all of the participants were in one geographical area and many lived in the same collection of buildings, he notes.

"We changed the procedure to call people and to have them count the pills over the telephone," Kalichman says.

The resulting study shows that the unannounced telephone calls work as well as the unannounced visits, he adds.

"There were some errors, but they were never more than a couple of pills off," Kalichman says.

Investigators combined both unannounced telephone calls to have participants count their pills while on the phone with a follow-up visit at home where study staff counted their pills as well. The result was 99 percent concordance, Kalichman says.

The high concordance surprised Kalichman: "I was concerned it wouldn't turn out so well, but when data were all entered, the mistakes turned out to be trivial," he says.

Investigators studying medication adherence could use this method instead of the more common and less accurate method of using self-reported adherence, Kalichman suggests.

"It's stigmatizing to miss your medications, and everybody knows about adherence and how it's not good to miss your antiretrovirals," he says. "So there is motivation for bias among patients, so they won't look bad to doctors."

But even when patients are honest with self-reporting, it's difficult for them to be highly accurate, Kalichman says.

"We're asking someone to remember something they've forgotten," he says. "When people report 100 percent adherence we tend to believe that in our research, and when people say they aren't taking any pills at all, we tend to believe that."

However, it's difficult for everyone else to recall how well they took their prescriptions more than for a few days at a time, Kalichman says.

Then there's the method of having patients bring in their pills to clinic appointments, and that monitoring strategy has two major problems, he says.

"One is that people don't bring everything they have, and so they'll say they have a bottle in their bathroom or they've forgotten their pill box," Kalichman says. "Having all of the pills available is critical for an accurate count, and it's difficult to achieve in an office visit."

Then there's the second problem of pill dumping in which patients won't bring all of their pills to the office because they don't want to have the clinicians see how many doses they've missed, he adds.

Kalichman says it would be very difficult for patients to engage in pill dumping during the unannounced telephone calls, because there isn't much time for someone to add up doses and numbers and come up with a lower number of pills to report than what they have in front of them.

For the research study, the telephone interviewers were trained to provide no judgments when participants gave their pill numbers, Kalichman says.

But if telephone pill-counting were used for the purposes of both monitoring and improving medication adherence among a clinic's patients, it could provide an instant opportunity for counseling, he suggests.

"With a doctor's office you could obtain the adherence rate immediately by plugging numbers into the database, which would tell you how many pills the patient had last time and how many were dispensed," Kalichman explains. "If the adherence rate was less than 95 percent, then the adherence nurse could say, 'John, I can see from your pill count that you missed a few doses, can we talk about that? Let's problem-solve and see what you could do differently for the next time.'"

For the study, 77 HIV-positive men and women in Atlanta received 13 monthly unannounced phone assessments and one unannounced home visit, but participants were not told the home visit would be shortly after the telephone visit.1

The study's logistics required home visitors to rely on dispatchers and global position systems (GPS) so they could get to a home within 20-30 minutes. Since the average telephone pill-counting session lasted 15 to 20 minutes, this meant the home visitors typically would arrive within five minutes of the person hanging up the telephone, Kalichman explains.

There were always three cars in the field, each assigned to a geographical area, and as soon as a telephone caller found someone at home, he or she would signal the dispatcher who would immediately send the home visitor to that residence, he adds.

"So the validation study was carefully planned and well-organized," he says.

Telephone pill-counting interviewers typically had to call several times before finding someone at home, but this wasted only seconds of their time, Kalichman says.

Also, for participants who didn't have reliable telephone service, the study provided them with free cell phones that had a service that could only be accessed by the trial staff. The phones couldn't be used to call out, only to receive calls, and the participants weren't given its number, he explains.

"We experienced some loss of phones, so it wasn't perfect," Kalichman notes.

But the key to the telephone pill-counting intervention is that it is far less expensive and just as accurate as home visits for pill counting, he adds.

Home visits, for instance, cost 44 cents per mile just for the driving expenses, and the home visitors drove eight to 10 miles to a home, on average, he says.

"And we had them visit homes when we knew somebody was going to be home, but what if you were to show up and nobody's there?" he says.

"The cost of unannounced home visits is cost prohibitive," Kalichman says.

In an HIV clinic, an adherence nurse could make the pill-counting phone calls, spending maybe 10 to 20 minutes on each phone call in which the patient was reached, he says.

"My real hope is this becomes the new thing and people find it as useful as we found it," Kalichman says.

"There are so few options for measuring adherence for research, and I think there are more people who will find it a good idea," he adds. "Our aim is to give it away; we're eager to share the protocol and database with anyone who is interested in using it."

[Editor's note: For more information about the telephone pill-counting study, contact Seth Kalichman, PhD, at the email address:]


  1. Kalichman SC, Amaral CM, Stearns H, et al. Adherence to antiretroviral therapy assessed by unannounced pill counts conducted by telephone. J Gen Intern Med. 2007;10:e-pub.
  2. Bangsberg DR, Hecht FM, Charlebols ED, et al. Comparing objective measures of adherence to HIV antiretroviral therapy: electronic medication monitors and unannounced pill counts. AIDS Behav. 2001;5:275-281.