Fracture risk in Parkinson’s - Mind the Gap

Fred is 79 and has had Parkinson’s Disease for about 10 years. He tripped and fell a couple of months ago in the garden and sustained a fragility fracture of his wrist, and is back to review his DEXA scan result. His femoral neck T score is -1.5, putting him in the osteopenia range. Should we be considering a bisphosphonate for him? But I thought people with osteopenia didn’t need bone protection treatment….

BMD alone is a poor predictor of fracture risk

For what feels like it should be a straightforward subject, I’m sure I’m not alone in thinking that osteoporosis (or more pertinently fracture risk) can actually be a surprisingly confusing area. One of the key messages that I’ve learned is that bone mineral density (BMD), based on DEXA scan is, on it’s own, a poor predictor of future fracture risk. As discussed in an excellent BMJ review and editorial the majority of people who sustain fragility fractures don’t have osteoporosis, and indeed some with osteoporosis are in fact at low risk of fracture and may not need treatment. The upshot is we need to base treatment decisions on a risk factor assessment, not just the BMD - and this is highly pertinent to Fred.

Most of us will be familiar with the FRAX assessment tool, and whilst this is much more accurate for fracture risk than using a BMD score alone, there are some key risk factors that are not addressed in the basic calculation. Important emerging risk factors include type 2 diabetes (especially duration >10 years and those on insulin), and Parkinson’s Disease (PD) - the latter was specifically addressed in the 2024 NOGG osteoporosis guideline update. 

Fracture risk in PD is significant and often underestimated 

The importance of fracture risk in those with PD, and the fact that it often goes under the radar, was highlighted in a paper last year updating the BONE-PARK algorithm, which addresses fracture risk in PD. The basic FRAX calculator significantly underestimates fracture risk in PD for two reasons - 1) the disease process in PD increases risk of fractures substantially, and 2) those with PD fall frequently (~40% experience recurrent falls), compounding that risk. Hip fracture risk is particularly high in PD, with hip fracture admissions accounting for 4.2% of all PD hospital admissions, and those that sustain hip fracture are much more likely than controls to develop complications, have more difficulty regaining mobility and have a 50% higher mortality rate. 

Treatment gap in PD

The result is a significant treatment gap, with potential under-treatment in PD. The evidence underpinning the updated BONE-PARK 2 protocol suggested that well over 2/3 of people with PD in the high risk group for fracture were not receiving bone protection treatment.

So how do we assess Fred? (NB: click on the links below for pictorial view)

Whilst reviewing how the fall happened (‘I was just a bit slow getting out of the chair and tripped over my toes’), we quickly assess his FRAX risk, with up to date weight (70kg) and height (180cm) (NB this should be in the DEXA results), tick ‘previous fracture’ box, and review the other risk factor boxes and add his femoral neck BMD T score of -1.5. This puts Fred squarely in the ‘low risk’ category for ‘lifestyle advice only’. 

However this does not take into account his PD, or the fact that you can see this is not the first time this year he’s ended up in ED with a fall when he could not get back up off the floor and needed a paramedic. The updated NOGG guidance (see table 2) recommends we tick the ‘rheumatoid arthritis’ box (even though they don’t have RA!) to adjust for the increased fracture risk in PD, as the increased risk in PD is thought to be equivalent to those with RA - this now puts his 10 year hip fracture risk to right on the threshold for treatment. Additionally as he has had recurrent falls (≥2 in the year) NOGG advise we should increase his 10 year hip fracture risk by a further 30%, putting him now well in the high risk/treatment bracket. 

BONE PARK 2 algorithm - an easy to use fracture risk assessment tool for PD

The BONE PARK 2 algorithm (click here for summary) summarises the updates from the NOGG guidance, but also has some other useful practical recommendations, including what to do if you have no DEXA result available - an important factor as some with PD will not be able to manage/have a DEXA scan. Importantly, the guidance also stresses that ‘Clinical judgement is necessary regarding patient preferences towards treatment, comorbidities and life expectancy’, and that if someone is near the treatment boundary but is either a very frequent faller or has more advanced PD or frailty we should assume they are in the higher risk category. 

Finally, it’s onto a discussion with Fred about starting a bisphosphonate for bone protection and seeing what we can do to reduce the risk of him falling in the first place.