Drug Burden Index

Medicines are a marvel of modern science. They can cure ailments, treat diseases, and even stave off death.

New medications seem to appear daily, offering up an endless supply of antidotes to every possible affliction. As this plethora of drugs becomes more readily accessible, people — especially older New Zealanders — are increasingly taking more medications and supplements than ever before, all with a view to increasing longevity and quality of life.

However this trend may be more harmful than good. The practice of taking many medications at once is known as ‘polypharmacy’, and it has been the source of rigorous debate amongst health professionals. All medications have benefits and side effects which doctors carefully weigh against each other when prescribing medicines to the patient. However, when prescribing medication to individuals already taking multiple pills, it is hard for a doctor to fully comprehend potential adverse interactions between so many drugs.

To tackle this problem, the Drug Burden Index (DBI) was developed in 2007. The DBI is an early warning system, a tool that calculates the total exposure of medications that sedate or affect cognition, and the adverse effects they might have on a patient. Essentially, it is a scale that adds up the side effects of medications and presents it in an easily understandable way for health professionals.

Researchers found that a high DBI score — that is, individuals on several sedative and/or cognitive medications at once — was associated with poor clinical outcomes for the individual. Subsequent studies proved the DBI to be a reliable tool, and therefore the scale could potentially be used to ensure patients were not on dangerously excessive medication regimens, and inappropriate prescribing could be curtailed.

And this is where Ageing Well Principal Investigator Associate Professor Hamish Jamieson came in. Associate Professor Jamieson, a geriatrician with the Canterbury District Health Board and an Associate Professor at the University of Otago, Christchurch, wondered if the DBI tool could also be used to predict falls and fractures.

To answer this question, Associate Professor Jamieson drew upon big data. Specifically, he tapped into a world-leading New Zealand asset: International Resident Assessment Instrument (interRAI).

InterRAI is an evidenced-based clinical assessment questionnaire, which was identified by the Ministry of Health in 2003 as the best tool for evaluating the health and social needs of older adults, and is used widely across the nation. Associate Professor Jamieson realised that the Home Care assessment (interRAI-HC), used to help older New Zealanders stay at home or plan for their care in residential facilities, could shed light on how often older adults suffered falls, and, more importantly, whether polypharmacy contributed.

“We had an opportunity to examine this through use of the big data available in New Zealand’s interRAI database on older people. The key advantage of using the interRAI data is that potential confounding factors can be accounted for,” Associate Professor Jamieson said. That’s because interRAI would better allow researchers to separate the actual causes of falls and fractures from other noncontributing factors that can sometimes appear.

Excluding these factors allowed the project to verify the DBI’s efficacy — a ground-breaking achievement. Mining big data is challenging: Harnessing the myriad tributaries of data and channelling them into one stream which can then be explored, is painstaking work. Associate Professor Jamieson and his team analysed interRAI data from over 71,000 older New Zealanders to measure the impact of multiple medications on the incidence of fractures. Using another national pharmaceutical database, they then matched and compared the participants’ medical and medication history.

The results were staggering. Dr Jamieson’s team found that those taking three or more high-scoring DBI medications (especially sedative and cognitive medications) were almost twice as likely to fall and break their hip. Ninety percent of fractures were the result of a fall, and between 20-30% of those fall victims died within a year. Up to half of those over the age of 60 were on at least one DBI medication, Dr Jamieson noted. Ultimately, the very drugs tasked with improving older adults lives were often negatively interacting with each other and causing falls.

The impact of falls and fractures are immense. Individuals can lose mobility, independence, endure a poor quality of life, and even require early admission into a residential care facility. In the worst-case scenario, it can lead to hospitalisation and death.

The issue of falls is a pressing one in New Zealand. The Accident Compensation Corporation (ACC) reports that, of one in seven New Zealanders over 65, around 30% to 60% suffer a fall each year. And 10-20% will end up in hospital with a fracture. Falls prevention is such an important matter that ACC co-launched a campaign to stem the tide of older New Zealanders falling so frequently: Live Stronger for Longer. Ageing Well’s Well Balanced Exhibit was part of that initial launch campaign.

But why were these drugs collectively such a danger to older New Zealanders?  The reason multiple medications cause falls is because of the side effects of the drugs and how each medication reacts with others creating additional, often unforeseen, consequences. The side effects of the medications could include drowsiness, blurred vision, dizziness, and confusion, Dr Jamieson says. And a number of factors predispose older people to medication side effects, including not being able to metabolise medications as effectively as young people.

The ramifications of Dr Jamieson’s study are significant for both the New Zealand public and policymakers. Most importantly, Associate Professor Jamieson recommends older patients regularly visit their GP to ensure that the combination of prescribed medication is examined. The study also provides evidence that the DBI could be a valuable tool for clinicians to use alongside electronic prescribing systems to help reduce falls in older people. Since completing the project, a flurry of studies have built—or are building— on this Ageing Well research, including a prestigious $1.1 million Health Research Council grant for Associate Professor Jamieson and his team to continue their important research.