Patient adherence to medical treatment: a review of reviews.
BACKGROUND
Patients' non-adherence to medical treatment remains a persistent problem. Many interventions to improve patient adherence are unsuccessful and sound theoretical foundations are lacking. Innovations in theory and practice are badly needed. A new and promising way could be to review the existing reviews of adherence to interventions and identify the underlying theories for effective interventions. That is the aim of our study.


METHODS
The study is a review of 38 systematic reviews of the effectiveness of adherence interventions published between 1990 and 2005. Electronic literature searches were conducted in Medline, Psychinfo, Embase and the Cochrane Library. Explicit inclusion and exclusion criteria were applied. The scope of the study is patient adherence to medical treatment in the cure and care sector.


RESULTS
Significant differences in the effectiveness of adherence interventions were found in 23 of the 38 systematic reviews. Effective interventions were found in each of four theoretical approaches to adherence interventions: technical, behavioural, educational and multi-faceted or complex interventions. Technical solutions, such as a simplification of the regimen, were often found to be effective, although that does not count for every therapeutic regimen.Overall, our results show that, firstly, there are effective adherence interventions without an explicit theoretical explanation of the operating mechanisms, for example technical solutions. Secondly, there are effective adherence interventions, which clearly stem from the behavioural theories, for example incentives and reminders. Thirdly, there are other theoretical models that seem plausible for explaining non-adherence, but not very effective in improving adherence behaviour. Fourthly, effective components within promising theories could not be identified because of the complexity of many adherence interventions and the lack of studies that explicitly compare theoretical components.


CONCLUSIONS
There is a scarcity of comparative studies explicitly contrasting theoretical models or their components. The relative weight of these theories and the effective components in the interventions designed to improve adherence, need to be assessed in future studies.
van Dulmen
Sandra
S
NIVEL (Netherlands Institute for Health Services Research), BN Utrecht, The Netherlands. s.vandulmen@nivel.nl
Sluijs
Emmy
E
van Dijk
Liset
L
de Ridder
Denise
D
Heerdink
Rob
R
Bensing
Jozien
J
D006801:Humans; D015201:Meta-Analysis as Topic; D010349:Patient Compliance / Q000523:psychology / Q000706:statistics & numerical data*; D010353:Patient Education as Topic / Q000379:methods; D017010:Reminder Systems; D012720:Severity of Illness Index; D012944:Social Support