More than half a million New Zealand adults are taking cholesterol-lowering medications, but a new University of Otago study reveals many are not taking them consistently.
Known as statins, the drugs are prescribed to two groups of people; those who have had an acute cardiac event or stroke (secondary prevention), and those at elevated risk of having one (primary prevention).
Dr Simon Horsburgh.
The researchers, Dr Simon Horsburgh, Finn Sigglekow and Associate Professor Lianne Parkin, all of the Department of Preventive and Social Medicine, examined statin adherence in patients prescribed the medicine for the first time in New Zealand between 2006 and 2013.
In their paper, published this week in the science and medicine journal PLOS One, the researchers compared the two user groups’ adherence to – (taking the drug as prescribed) and discontinuation of statin therapy (where a person was not in possession of the drug for more than 90 days).
Of the 238,855 people in their first year of taking statins prescribed for primary prevention, adherence was less than optimal in about 88,850 (37 per cent), while 98,890 (41 per cent) discontinued at least once.
Of the 50,811 patients in their first year of taking statins after an acute event, adherence was less than optimal in about 12,140 (23 per cent), and 13,620 (26 per cent) stopped taking them for at least 90 days at least once.
Researchers also identified that those who left a gap between getting their first prescription and second, were more likely to discontinue.
Dr Horsburgh says the results are concerning.
“Statins are a really common medication – over half a million New Zealanders were dispensed one in 2019. Most adults in New Zealand will either be taking one or have someone they know well who is.
“They are an effective tool for reducing the risk of some potentially serious or fatal health events, but the benefits of statins are significantly reduced if people do not take them consistently,” he says.
People in the secondary prevention group – those who had suffered a cardiac event or stroke – were 55 per cent more likely to be adherent and 33 per cent less likely to discontinue than people in the primary prevention group.
“For people taking statins for primary prevention, they really are taking them to prevent an event that has not occurred yet. Also, high cholesterol does not have any symptoms, so the importance of taking their statin regularly can feel abstract.
“People in the secondary prevention group are almost certainly more motivated by the fact that they have had an event, and also by the fact that they are generally at elevated risk of another event because of it and will have been told this. The importance of taking their statin medication is likely to be far less abstract,” Dr Horsburgh says.
When looked at by ethnicity, the results were “deeply concerning”. Almost 39 per cent of Māori patients and 45 per cent of Pacific patients in the primary prevention group discontinued the medication. That compares with 26 per cent of the primary prevention group for New Zealand European users.
“This is of particular concern when these groups are also at greater risk of death from cardiovascular disease. These findings feed into the already-large literature highlighting the inequities of healthcare service experience, particularly for Māori and Pacific people.”
Accessibility is a key issue for these groups and reinforces the need for the health system to consider the way in which it delivers healthcare, he says.
“Medication adherence, as measured by picking up prescribed medicines, provides some insights into how well our health system is doing in delivering an important health intervention (medicine), and whether it works better for some groups than others.”
While the study does not point to specific things clinicians can do to improve adherence, the relatively high levels of non-adherence in some groups may lead them to more closely consider how they can improve the adherence.
“It really highlights the need for conversations with their patients about challenges with adhering to their medications and how these can be mitigated, or thinking about how services are provided to make medicines more readily accessible for people in their communities.
“The finding that a gap between the first and second dispensing is associated with subsequent discontinuation was a novel finding within the literature, and may be a useful indicator for clinicians to use to try to identify people at increased risk of poor adherence so that they can intervene early on.”