Medication beliefs, treatment complexity, and non-adherence to different drug classes in patients with type 2 diabetes.
OBJECTIVE
To assess the relationship of patients' medication beliefs and treatment complexity with unintentional and intentional non-adherence for three therapeutic groups commonly used by patients with type 2 diabetes.


METHODS
Survey data about adherence (Medication Adherence Report Scale) and beliefs about medicines (Beliefs about Medicines Questionnaire) were combined with prescription data from the Groningen Initiative to ANalyse Type 2 diabetes Treatment (GIANTT) database. Patients were classified as being adherent, mainly unintentional non-adherent, or partly intentional non-adherent per therapeutic group (glucose-, blood pressure-, and lipid-lowering drugs). Treatment complexity was measured using the Medication Regimen Complexity Index, which includes the dosage form, dosing frequency and additional directions of taking the drug. Analyses were performed using Kruskal-Wallis and Mann-Whitney U-tests.


RESULTS
Of 257 contacted patients, 133 (52%) returned the questionnaire. The patients had a mean age of 66years and 50% were females. Necessity beliefs were not significantly different between the adherers, mainly unintentional non-adherers, and partly intentional non-adherers (differences smaller than 5 points on a scale from 5 to 25). For blood pressure-lowering drugs, patients reporting intentional non-adherence had higher concern beliefs than adherers (8 point difference, P=0.01). Treatment complexity scores were lower for adherers but similar for mainly unintentional and partly intentional non-adherers to glucose- and blood pressure-lowering drugs.


CONCLUSIONS
Treatment complexity was related to non-adherence in general. Beliefs about necessity were not strongly associated with non-adherence, while patients' concern beliefs may be associated with intentional non-adherence. However, the role of these determinants differs per therapeutic group.
Department of Clinical Pharmacology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands. Electronic address: s.t.de.vries@umcg.nl.
Sieta T
ST
de Vries
Department of Endocrinology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands; Van Swieten Research Institute, Martini Hospital, Groningen, The Netherlands. Electronic address: j.keers@mzh.nl.
Joost C
JC
Keers
Department of Endocrinology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands; University of Groningen, University Medical Center Groningen, The LifeLines Cohort Study, Groningen, The Netherlands. Electronic address: r.visser02@umcg.nl.
Rosalie
R
Visser
Department of Clinical Pharmacology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands. Electronic address: d.de.zeeuw@umcg.nl.
Dick
D
de Zeeuw
Department of Clinical Pharmacology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands. Electronic address: f.m.haaijer-ruskamp@umcg.nl.
Flora M
FM
Haaijer-Ruskamp
Department of Clinical Pharmacology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands. Electronic address: j.voorham01@umcg.nl.
Jaco
J
Voorham
Department of Clinical Pharmacology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands. Electronic address: p.denig@umcg.nl.
Petra
P
Denig
D000368:Aged; D003430:Cross-Sectional Studies; D003469:Culture; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy* / Q000523:psychology*; D005260:Female; D058006:General Practice / Q000706:statistics & numerical data; D007722:Health Knowledge, Attitudes, Practice; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use*; D008297:Male; D009426:Netherlands; D010349:Patient Compliance / Q000706:statistics & numerical data; D011159:Population Surveillance; D011795:Surveys and Questionnaires; D016903:Drug Monitoring
D007004:Hypoglycemic Agents
Intentional and unintentional non-adherence; Medication beliefs; Treatment complexity; Type 2 diabetes