Does NEXUS work in the elderly?

There aren’t a lot of studies specifically examining whether the NEXUS criteria are reliable (e.g. don’t miss important C-spine injuries) in the elderly.

Most of the big studies that derived and validated the NEXUS rule enrolled patients of all ages, so they do include this population. But their average age was much younger (20s-40s in most cases), so if you pick out the older subset, you’ll knock down the n from thousands down to much less. (That would be equally true if you asked about validity for any other small age range, of course.)

So how many older patients has NEXUS been applied to? It’s hard to know. Neither the original NEXUS derivation nor the validation give full age breakdowns, although their range does go up past 100, so there were some patients in that older group. It’s a similar story in a retrospective chart application using NEXUS, and in a study that compared NEXUS with the Canadian C-spine rule. These are all studies with thousands enrolled, though, so even in the subsets the numbers should have some weight.

Domeier 2005 studied a modified NEXUS for prehospital use, and they do give an age breakdown; eyeballing the chart it looks like about 1900 total enrolled age 75+. They found an overall sensitivity that was a little lower than in the other studies, about 92%, and it’s true that a fair number of their injuries were in the older cohort, but none of the missed injuries mattered (no clinical sequelae).

Now, Goode 2014 was just released and seems to be one of the only studies specifically addressing this. They concluded that NEXUS wasn’t very sensitive with age >65, with sensitivity only 65.6%. However, the sensitivity below 65 was only 84.2%, which is dramatically less than in the other studies, so they’re clearly doing something different; if we trust these numbers we shouldn’t be using NEXUS for anybody. Mainly, the difference seems due to higher a high-risk population enrolled; they only looked at patients with

… associated injuries from high-energy mechanisms (e.g., pelvic/long bone fractures), ejection from a vehicle, death in same compartment vehicle, fall from greater than 20 feet, vehicle speed greater than 40 mph, major vehicle deformity/significant intrusion, and pedestrian struck with speed greater than 5 to 20 mph.

In other words, big-sick trauma activations, not the “all blunt trauma” population used in the other studies. This is reflected in the higher rate of C-spine fracture in both groups: 7.4% in the young and 12.8% in the old, which is far higher than the ~2% rate of fracture in most other studies. Since it’s unlikely that these types of patients are getting clinically cleared anyway — no matter what, they’re getting a collar from most EMS crews and a CT scan from most EDs — I’m not sure how useful this data is. NEXUS is for small injuries with patients that look okay, not multi-system trauma codes.

So do older patients qualify for NEXUS? The data is not as robust in defense of this practice as for younger patients, certainly. But it does support its use; none of the major NEXUS studies put a cap on age and they all included at least some age >75 or >85 or whatever.

If you are very worried it may be reasonable to insist upon a specific study validating this age range, with enough power to focus on that specific population, but I’m not sure why you should be so worried. Although they may be at higher risk for fracture, that’s not the issue; the issue is whether the NEXUS criteria can detect those fractures, and I don’t think there’s any good reason to say that all old patients can’t reliably report pain or neuro deficits. Obviously selected patients, for instance with cognitive impairment, peripheral neuropathies, or other conditions may present obstacles, but hopefully your clinical judgment would already tell you that you may not be able to clinically clear those people anyway. NEXUS specifically has caveats to skip patients patients who can’t reliably report their symptoms — intoxicated, distracting injury, AMS — and if there’s something present which isn’t on that list but is still confounding things, you probably shouldn’t clear them. When it comes to corner cases, use the principles, not the letter of the law.

If anybody is really worried about this we can perhaps write to Hoffman or some of the other authors and ask if they have the age breakdowns for their big studies; that way we’d know exactly how many older folks have actually been studied.

Or just use the Canadian C-spine rule, which includes age >65 as an exclusion anyway. (Yep, it’s been validated for prehospital use as well.)

Determining Risk/benefit Using Test Thresholds

A quick illustration of how to drill down on the group of people in a cohort who actually benefits from a course of care, and compare it against the group who is harmed. Important, important stuff when it comes to reading any study.