Though half of patients do not take their medications as prescribed, an updated review suggests there are no documented effective interventions in place, prompting researchers to call for better trials on the topic.
The research, led by Robby Nieuwlaat at McMaster University in Canada, is published in The Cochrane Library.
Previous studies have found that patients prescribed medicines only take about half of their doses, and many stop their treatment entirely. In other cases, patients do not properly follow the instructions for taking their meds.
But when effective drug treatments are available for a condition, they can significantly improve the patient's health, according to medical experts. As such, researchers have tested ways to assist in better adherence to medication.
The team from this updated study reviewed data from 182 such trials that tested different approaches aiming to increase medication adherence and, as a result, to increase patient health.
However, though the current review included the best studies on the topic to date, many of them had problems in design, making it difficult to identify which approaches were effective. What is more, trial evidence was often "unreliable and inconsistent."
In detail, the team found that the studies differed widely in terms of patients, treatments, adherence intervention types, medicine adherence measurement and clinical outcomes.
"The studies varied so much in terms of their design and their results that it would have been misleading to try to come up with general conclusions," says Nieuwlaat.
Only five trials suggested improvements in adherence and patient health
To conduct their analysis, the team assessed trials studying various medical conditions, including HIV and psychiatric disorders, as well as those that trialled medication adherence interventions.
The reason it was difficult for the researchers to come to any conclusions about whether any of the interventions was effective is that they all showed wide-ranging effects on adherence and patient health. In addition, the effects were measured using wide-ranging methods.
Many of the trials were unreliable on their own, casting doubt on the validity of their results. As such, Nieuwlaat says there need to be "larger and higher quality trials, which better take in account individual patient's problems with adherence."
Of the 182 trials they reviewed, the researchers found that only 17 were of high quality because they tested combinations of different approaches, including family and pharmacist support, education and counselling.
And only five of these trials suggested improvements in health outcomes for patients and increased medication adherence.
Commenting on their findings, the researchers write:
"It is uncertain how medicine adherence can consistently be improved so that the full health benefits of medicines can be realized. We need more advanced methods for researching ways to improve medicine adherence, including better interventions, better ways of measuring adherence and studies that include sufficient patients to draw conclusions on clinically important effects."
As a result of their findings, the team is calling on the research community as a whole to come together to address these issues. They have even created a database of the trials from their review so that they can be made available for more in-depth analyses.
"By making our comprehensive database available for sharing," says Nieuwlaat, "we hope to contribute to the design of better trials and interventions for medication adherence."
"We need to avoid repeating the painful lessons of adherence research to date and begin with interventions that have shown some promise, or at least have not produced repeatedly negative results," he concludes.
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