Toward identifying the causes and combinations of causes increasing the risks of nonadherence to medical regimens: combined results of two German self-report surveys.

OBJECTIVES: This study aimed to identify the causes of the nonadherence (NA) of German patients to their prescribed medication. In the course of the investigation, the NA risk profiles resulting from the combination of the various causes were identified.
METHODS: Two cross-sectional surveys with a total of 1517 patients (comprising 1177 patients contacted by telephone and forming survey 1 and a different set of 340 patients interviewed in-depth and face-to-face forming survey 2) were conducted. Self-reported NA was measured by the generic Morisky Medication Adherence Scale (MMAS). Survey 1 used a four-item MMAS and Survey 2 an eight-item MMAS.
RESULTS: Approximately 35% to 40% of the patients can be described as nonadherent. In survey 1, a few causes explain the NA (chronic disease, younger age, and fewer medications required to be taken). The more detailed survey 2 shows that the existence of intentional NA has considerably more influence than any other causal factors. Positive medication beliefs, a positive mood, and a good patient-doctor relationship reduce the NA risk. Furthermore, patients who are easily able to recognize the correct medication, as evidenced by ability to correctly identify the packaging, have a reduced NA probability. Concerning additive risk, patients who are chronically ill but display no other causes of risk have an NA probability of 10.4%. By contrast, in patients displaying all the identified causes of risk, the rate increases to 93.9%.
CONCLUSIONS: About one-third of patients can be classified as nonadherent. Intentional/medication-based NA causal factors explain the NA considerably better than do socioeconomics. The existence of more than one cause of risk considerably increases the NA risk of a patient.