Abstract
Aim
Management of bone and joint infection can be technically complex and often requires a prolonged course of antibiotics. Traditionally, bone and joint infection management utilises nurse-led outpatient parenteral antibiotic therapy (OPAT) where adherence is unlikely to be an issue. However, with increasing evidence in favour of oral therapy, the question of adherence merits further consideration. We describe the adherence of both oral (PO) and self-administered intravenous (IV) antibiotics in the treatment of bone and joint infection using paper questionnaires (8-item Modified Morisky Adherence Score (MMAS)) and, in a subset of participants, electronic pill containers (Medication Event Monitoring Systems*).
Method
All eligible participants enrolled in the OVIVA trial (2010–2015) were randomised to six weeks of either PO or IV antibiotic treatment arms. Self-administering patients were followed up with questionnaires at day 14 and 42. A subset of PO participants was also given the medication event monitoring system* in order to validate the adherence questionnaires. The results were correlated with treatment failures at one-year follow-up.
Results
1,054 participants were enrolled in the OVIVA study. At day 14, 68% of participants recorded high adherence in both the IV (N=72) and PO arms (N=303) using the 8-item MMAS. At day 42, only 51% maintained high adherence in the PO arm (N=323) as compared to a 68% in the self-administered IV arm (N=80). The medication event monitoring system* results at day 42 demonstrated that 51% of participants achieved adherence of 100% (range 45–100). There was no statistically significant correlation between adherence and treatment failure in either randomised treatment arm.
Conclusions
This is the first large scale study to quantitatively assess compliance with antibiotics in bone and joint infections using established adherence tools. Our results suggest that oral antibiotic adherence decreases significantly over time. Despite the absence of apparent excess risk of therapeutic failure in this trial, we strongly advise careful patient education and adherence support in order to optimise clinical outcomes.
Acknowledgements
The OVIVA study is funded by the National Institute for Health research (Health Technology Assessment); project number 11/36/29.
*MEMS® Medication Event Monitoring System
