A new Australian study has found that patients presenting with intermittent claudication who undergo revascularization had a higher risk of amputation than those who don’t. Yes, you read that correctly, they had more amputations. But, as we always say is that the full story?
This study was led by DFA’s friend and internationally-acclaimed PAD research guru, Professor Jon Golledge and his team from the Queensland Research Centre for Peripheral Vascular Disease. So when Prof Golledge publishes something big like this in one of the leading surgery journals in the world the British Journal of Surgery, it is always worth the read.
What do we know about intermittent claudication?
Intermittent claudication is often described by patients as a cramp-like feeling in their calf muscle area after walking for a certain distance which resolves after a short rest. As we summarised in a recent BMJ PAD update, intermittent claudication is typically a symptom of more severe PAD, but can be hidden by peripheral neuropathy in patients with diabetes.
Recommended treatment for intermittent claudication is either via exercise programs, endovascular or open bypass revascularization procedures. However, studies testing these interventions have been limited and have mostly focused on improving treadmill walking distance rather than ‘harder’ outcomes like amputation. And that is where this new study from Prof Golledge and colleagues just might help.
What did this new study do then?
This observational study recruited patients visiting 1 of 3 outpatient vascular services in 2002-2016. To be included, patients had to be diagnosed with PAD by a vascular surgeon, report intermittent claudication symptoms and be able to be followed-up for at least a year. They then collected a whole raft of baseline sociodemographic, diabetes history, smoking history, co-morbidity history, medication history, PAD history and ankle brachial index (ABIs) characteristics.
All patients were then managed as per usual by their treating vascular surgeon. For all patients this involved at least usual conservative treatment of medical management and exercise advice. Medical management included trying to control any high blood pressure, lipids and glycaemia, and stopping smoking. Exercise advice included recommending patients walk 3 times per week for 30 minutes each. After conservative treatment, the treating surgeon decided if their patient needed a revascularization procedure performed or not within the first 6 months (“early revascularization”), and if so performed it.
All patients were then followed for as long as possible at usual outpatient vascular surgery appointments and by using standard hospital data to see if they had another revascularization procedure, major amputation (above ankle), stroke, heart attack or died. The researchers then compared the data from the patients that received initial conservative treatment only (“conservative group”) to those who also had early revascularization (“revascularization group”).
So what did they find?
They recruited 456 patients: 39% in the “revascularization group” and 61% in the “conservative group”. They found the two groups had similar baseline characteristics, except the revascularization group had more smokers, higher average eGFR, lower average BMI and slightly lower average ABI (0.58 v 0.66). The procedures in revascularization group were 51% endovascular, 46% open and 3% a combination.
They then followed patients for an average of 5 years and found that the revascularization group had similar rates of stroke, heart attacks and deaths to the conservative group; but had more major amputations (5.1% v 1.1%) and follow-up revascularization procedures (45.5% v 28.8%).
They then compared the 12 patients that had a major amputation (12) to the 444 patients that didn’t. And using some complex statistical models to control for other baseline characteristics (including ABI), they found that the only independent factors that predicted major amputation in those presenting with intermittent claudication was low BMI and undergoing revascularization.
What was good or not so good about this study?
This study had many strengths, including: i) large numbers of patients recruited from multiple sites; ii) large numbers of robustly collected baseline characteristics; iii) treating vascular surgeons able to provide treatment as per normal to reflect usual care; iv) patients were followed-up for a long period; v) they used outpatient vascular clinic records and standard hospital coded datasets to identify outcomes; and vi) they used complex robust statistics that adjusted for a range of potential confounding factors.
But, as with all studies it wasn’t without limitations, including: i) this was not a randomized control trial specifically designed to detect differences; ii) ABIs were measured in only ~60% of patients which limits accurate representation of overall PAD status; iii) other recommended non-invasive vascular tests such as toe pressures were not collected as particularly recommended for those with diabetes; iv) claudication is sometimes not experienced by diabetes patients and thus these findings may not automatically translate to diabetes patients; v) no foot ulcer or amputation history characteristics were reported which are often found to be predictors of future amputation; vi) there were only a very small number of major amputations which means results from statistical models can be a little imprecise; and vii) patients were recruited over 15 years, meaning some revascularization techniques may have improved over that time which may have confounded findings.
So what does that all mean?
Well, the authors summed it up nicely by stating, “patients presenting with intermittent claudication who underwent early revascularization appeared to be at higher risk of amputation than those who had initial conservative treatment.”
At first glance these findings seem counter-intuitive. Yet, other studies have also found that undergoing initial revascularization increases the risk of needing future revascularization, plus, it limits the future options for revascularization procedures which brings an amputation option more into play.
These findings, in combination with previous studies, suggest that exercise treatment for patients with intermittent claudication produces similar symptom relief and quality of life outcomes to having a revascularization procedure, plus, decreases the risk of future amputation and revascularization.
Then why do revascularization procedures in these patients you ask? Well there’s probably a few reasons, including: revascularization provides much more immediate symptom relief to patients than does exercise programs and revascularization is publicly funding, whereas exercise programs are not.
However, after this study, perhaps we should be advising our patients that the best option for their intermittent claudication really is good medical management and exercise programs. Then if that doesn’t work we can offer revascularization as an option. And wouldn’t it be great if in future we could also refer out patients with intermittent claudication to a publicly funded team consisting of vascular surgeon and exercise physiologist aimed at preventing amputation. Now that would help bring us closer to our national goal of ending avoidable amputations in a generation.