How to Assess Adherence
The degree of patient adherence to medication regimens can be determined from information gathered from the patient, physician or pharmacist, family members, and friends. Adherence can also be shown by counting pills or examining biochemical evidence.
Asking the physician may unfortunately turn out to be the poorest of choices. Physicians generally overestimate their patients' compliance rates and, even when their guesses are not overly optimistic, they are usually wrong. One early study reported a correlation of only.01 between physicians' estimates of compliance and an objective pill count. Asking patients themselves is a more valid procedure, but it is fraught with difficulties. The same study showed that about 10% of the patients claimed that they were 100% compliant; however, a pill count of the medications indicated that the patients were using from 2% to as much as 130% of the prescribed pills. Some patients took more medication than recommended, and others took far less.
Self-reports are inaccurate for at least 2 reasons: Patients may lie to avoid displeasing their physicians or they may simply not know their rate of compliance. Patients not only underreport poor adherence but also overreport good adherence.
To improve overall adherence/ compliance rates, trained interviewers could help improve the accuracy of self reports and, at the same time, identify the types of medication errors typically made by patients. Constant observation by family, friends, or hospital staff may be physically impossible, and the quality of family relationships can affect accuracy. Pill counts -- pills gone from the bottle minus pills dispensed -- may seem ideal because of the mathematical certainty; however, even if the required number of pills are gone, the patient may not have been compliant. The patient, for a wide variety of reasons, may have discarded some of the medications or taken them in a manner other than had been prescribed.
In some cases, biochemical evidence from urine or blood samples can indicate whether there is medication adherence. While blood and urine levels may be more reliable measures of medication intake than pill counts, this approach may not be worth the cost or the risk of decreasing the level of trust between physician and patient. In addition, some drugs are not easily detected in blood or urine, and individual differences in absorption and metabolism of drugs can lead to a wide variation among people who are equally compliant. This is the case especially for the elderly patient population, in whom absorption rates and metabolism are an issue. Furthermore, biochemical checks may reveal that the patient ingested some amount of the drug at some time, but it may not indicate that the patient took the proper amount at the proper time as prescribed.
While there is no foolproof method that will guarantee the detection of adherence or nonadherence, physicians are encouraged to try more than 1 strategy and to implement an adherence plan early in the treatment process.
© 2000 Cliggott Publishing, Division of CMP Healthcare Media
Cite this: Medication Nonadherence: Finding Solutions to a Costly Medical Problem - Medscape - Jun 01, 2000.