Elsevier

Cancer Epidemiology

Volume 38, Issue 3, June 2014, Pages 214-226
Cancer Epidemiology

Adherence influencing factors in patients taking oral anticancer agents: A systematic review

https://doi.org/10.1016/j.canep.2014.03.012Get rights and content

Abstract

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.

Purpose

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.

Introduction

The use of oral anticancer agents (OACA) has increased steadily. One quarter of newly developed anticancer agents can be taken orally [1]. The use of OACA will probably increase further. Most patients prefer to take their medication orally [2]. Adherence, defined as “the extent to which a patient acts in accordance with the prescribed interval and dose of a dosing regimen” [3] is lower in patients taking OACA compared to patients treated with intravenous chemotherapy [4]. It is estimated that adherence rates in patients taking OACA lie in a range between less than 20% and 100%, depending on patient characteristics, therapy and adherence measurement and definition [5], [6]. For some cancer types adherence to OACA turns out to be crucial factor for the success of treatment [7], [8], [9], especially given the long period in which OACA have to be taken correctly. Consequently, adherence has become a key issue in modern oncology treatment. There are several factors that can potentially influence patient adherence [10]. In clinical practice the knowledge about factors that influence patient adherence can help to identify patients at risk for non-adherence and also help to develop methods to improve adherence in affected populations.

The objective of this systematic review was to identify adherence influencing factors in patients taking OACA.

Section snippets

Sources

This systematic review was prepared according to the standards of the Cochrane collaboration, recommendations for systematic reviews of prognostic factors, and reported according MOOSE [11], [12], [13].

A systematic literature search was performed in MEDLINE (via Pubmed) and Embase (via Embase). The search strategy comprised several terms and medical subject headings related to adherence and OACA (the full search strategies are available in Supplement I). The search was performed in December

Literature search

After deducing duplicates the search in electronic databases resulted in 2309 hits. After title and abstract screening 95 seemed potentially relevant and full-text versions were screened in detail. Finally 23 publications of 22 studies were included [7], [8], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29], [30], [31], [32], [33], [34], [35], [36], [37]. The manual search and reference-check revealed no further relevant publications. The flowchart illustrates the

Discussion

Age, ethnic status, social support, depression, intake of aromatase inhibitors, number of different medications, and out-of-pocket costs seem to have an effect on adherence. The remaining factors either showed mostly no influence or a clear conclusion is not possible, because the results differed between studies. Due to the heterogeneity no general conclusions for all factors, – also for those emphasized above can be made that can be applied to all indications, medications, settings, countries

Conflict of interest

This work was funded by Janssen-Cilag Germany. There is no other conflict of interest.

Funding

This work was funded by Janssen-Cilag Germany. The sponsor has no influence on the study design, and in the collection, analysis and interpretation of data. Janssen-Cilag Germany has reviewed the manuscript and provided comments. The final decision to include the comments and the decision to submit the manuscript for publication was made only by the authors.

Authorship

All authors have made substantial contributions and approved the conceptions, drafting, and final version of the manuscript.

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