Adherence influencing factors in patients taking oral anticancer agents: a systematic review.
BACKGROUND
The use of oral anticancer agents increased steadily in the last decades. Although oral anticancer agent adherence is important for a successful treatment, many patients are insufficiently adherent.


OBJECTIVE
To evaluate adherence influencing factors in patients taking oral anticancer agents.


METHODS
A systematic literature search was performed in Medline and Embase. Titles and abstracts and in case of relevance, full-texts were screened according to predefined inclusion criteria. The risk of bias was assessed. Both were carried out independently by two reviewers. Relevant data on study characteristics and results were extracted in standardized tables by one reviewer and checked by a second. A meta-analysis was not performed because of clinical and methodological heterogeneity between the studies to avoid misleading results. Data were synthesized in narrative way using a standardized procedure.


RESULTS
Twenty-two relevant studies were identified. The study quality was moderate. Especially the risk of bias regarding the measurement of influencing factors and adherence was mostly unclear. Social support, intake of aromatase inhibitors, and lower out-of-pocket costs for OACA seem to have a positive effect on adherence. Depression and the number of different medications seem to have a negative effect on adherence. Low age and very high age seem to be associated with lower adherence. The remaining factors showed either mostly no influence or were heterogeneous regarding the effect direction and statistical significance.


CONCLUSIONS
There are some factors that seem to have influence on adherence in patients taking OACA. However, due to the heterogeneity no general conclusions can be made also for these factors that can be applied to all indications, medications, settings, countries etc. The results should rather be considered as indications for factors that can have an influence on adherence to OACA.
Institute for Research in Operative Medicine, Faculty of Health - School of Medicine, Witten/Herdecke University, Ostmerheimer Str. 200, Building 38, D-51109 Cologne, Germany. Electronic address: Tim.Mathes@uni-wh.de.
Tim
T
Mathes
Institute for Research in Operative Medicine, Faculty of Health - School of Medicine, Witten/Herdecke University, Ostmerheimer Str. 200, Building 38, D-51109 Cologne, Germany. Electronic address: Dawid.Pieper@uni-wh.de.
Dawid
D
Pieper
Institute for Research in Operative Medicine, Faculty of Health - School of Medicine, Witten/Herdecke University, Ostmerheimer Str. 200, Building 38, D-51109 Cologne, Germany. Electronic address: Sunya-Lee.Antoine@uni-wh.de.
Sunya-Lee
SL
Antoine
Institute for Research in Operative Medicine, Faculty of Health - School of Medicine, Witten/Herdecke University, Ostmerheimer Str. 200, Building 38, D-51109 Cologne, Germany. Electronic address: Michaela.Eikermann@uni-wh.de.
Michaela
M
Eikermann
D000284:Administration, Oral; D000970:Antineoplastic Agents / Q000008:administration & dosage*; D006801:Humans; D055118:Medication Adherence; D009369:Neoplasms / Q000188:drug therapy* / Q000523:psychology
D000970:Antineoplastic Agents
Medication adherence; Neoplasms; Oncology; Oral anticancer agents; Oral chemotherapy; Patient compliance; Risk