Adherence to secondary prevention medications – even above an arbitrary adherence threshold of 80% – improves survival following first-ever stroke or TIA, according to Australian research.
The study linked data from the Australian Stroke Clinical Registry, medication dispensing and medical claims, and the National Death Index. The cohort was more than 8,000 adults with first-ever stroke or TIA surviving to one year, and then followed up for a further two years.
The study, published in Stroke, found the median adherence or proportion of days covered (PDC) with secondary prevention medications was above 85% for antihypertensives, statins and antithrombotic agents.
“For antihypertensive agents, a continuous reduction in the risk of mortality was observed for any increase in PDC adherence. Whereas for statins and non-aspirin antithrombotic agents, reductions in the risk of mortality, as shown by a declining slope, were observed for PDC values between 60% and 100%.”
“Between 60% and 100% PDC, each 10% increase in adherence was associated with a 13% reduction in all-cause mortality for antihypertensive agents (95% CI, 5%–19%) and statins (95% CI, 5%–20%), and a 15% (95% CI, 7%–21%) reduction for non-aspirin antithrombotic agents.”
The investigators said their findings suggest the commonly used target of 80% medication adherence may be inappropriate given they observed additional survival benefits at even greater levels of adherence.
“These findings represent important implications for practice by highlighting the value of efforts to improve medication adherence poststroke/TIA, even among patients with near-perfect adherence.”
“Similar to earlier research in patients with myocardial infarction, we present evidence to show that a target of 100% medication adherence was associated with optimal survival compared with all lower values of adherence for statins and antihypertensive agents.”
They said targeted initiatives to maximize medication adherence after stroke/TIA included medication reminder systems, mobile health technologies, increased follow-up by clinicians or complex behaviour change programs.
“Given the variability of adherence scores and the large proportion of patients with incomplete adherence in our cohort, there remains considerable scope for further interventions to improve medication adherence in Australia.”
Senior investigator Associate Professor Monique Kilkenny, Head of the National Stroke Data Linkage Program at Monash University, told the limbic the study clearly showed that 100% adherence provided better survival than 80%.
“And the reason we did this paper is that … all the trials and cohort studies say 80% but there is no evidence for why it is 80%. I think 80% is not good enough. I think it should be 100%.”
She said while median adherence to secondary stroke prevention medications was high in their cohort, they still found that 1 in 4 patients had adherence below 35%.
Associate Professor Kilkenny said there currently wasn’t a gold standard regarding strategies to improve adherence.
“There are different approaches that will work for different patients such as blister packs, mobile apps, a Pillo device – not currently available in Australia – which dispenses medication and if not dispensed it calls the carer, and there are also educational interventions which can improve adherence.”
She said GPs were crucial to checking on medication adherence given most patients will only see their neurologist once after a hospital stay.
“Every encounter with a medical practitioner is a shot at providing patient education and advice on medication adherence.”
“In the future, what I’d like to see is a type of streamlined intervention to make it easier to ensure all patients with stroke have been prescribed, and once they have been prescribed they have been dispensed by a pharmacist, and then more importantly that the patients are actually taking the medications as well.”
The study was led by Monash University PhD candidate Lachlan Dalli.