Effect Measure

“Falls” lead the injury pack

The National Health Interview Survey (NHIS) has been conducted since 1957 and is one of the main instruments to get a glimpse at the health of the US population. The NHIS is a “multistage area probability design,” or what many call cluster sampling. The idea is to first sample geographic areas in all 50 sates and the District of Columbia, where the area might be a county, a small adjoining group of counties in sparsely populated places or a metropolitan area where population is dense. The list of areas to be sampled has about 1900 entries and 428 are drawn at random, although all states are sampled. So that’s the first stage. Within these primary sampling units subsamples of either 8, 12 or 16 addresses are then drawn or a sample of 4 housing units built after the year 2000. The sample isn’t a straight random sample of the population as Blacks, Hispanics and Asians are oversampled via a screening procedure or by including areas known by the previous census to have higher numbers of these demographic groups. You can read more details at the NHIS site. Interviewing of sampled households goes on throughout the year to get a representative sample of adult, non-institutionalized resident of the US. Participation is voluntary, but response rates exceed 90%, which is pretty amazing.

This week CDC released results about rates of injury episodes collected via NHIS interviews from 2004 to 2007. An injury episode was defined to be “physical damage to the body from external causes resulting from traumatic events, which can include intentional or unintentional injuries.” The question asked was whether there was a nonfatal, medically attended injury in the 5 weeks preceding the interview. Here “external cause” refers to how the injury took place, although CDC uses (to this epidemiologist’s eyes) at least one strange category as “cause”: cut or pierce, which is an effect, not a cause. I’m told this has to do with coding of external causes in discharge diagnoses, but I don’t really know. In any event, here are the results for the “causes” of “falls,” “overexertion,” “struck,” “transportation,” and “cut or pierced”:

i-b5e3acf96fda9c3f2b5e937676861abf-Injury quickstat.jpg

Source: CDC, MMWR

Definitions: “Overexertion” denotes excessive physical exercise or strenuous movements in recreational or other activities; “struck” denotes being struck by or against an object or person; “transportation” denotes trauma involving motor vehicles, bicycles, motorcycles, pedestrians, trains, boats, and airplanes; and “cut or pierced” denotes being cut or pierced by instruments or objects.

We see immediately that the big category here is “falls,” accounting for almost 40% of the total, double any other cause. This was true for both males and females, but the rate for females was 17% than for males. On the other hand, females had a 35% lower rate of being struck and a 50% lower rate of being cut or pierced (as an injury, not as adornment). But falls is the big one.

The single category of falls hides a complicated event. I’m no injury expert, but I know there are different kinds of falls, some on the same level (tripping on a throw rug or toy) or from different levels (down steps, off platform or ladders) and affect different age groups differently, with the elderly being at special risk. It’s my impression that the rate of falls in the elderly has been increasing and I’m not sure if it’s know why, but one can speculate that, on the one hand, it’s because the elderly are in better shape and more active, hence more at risk of falls, or that multiple medications for blood pressure or anti-depressants might be involved. Certainly bad weather and poor vision are other risk factors. The cost in hospitalizations and emergency room visits is considerable, with older women being particularly important in this regard. And according to one source I consulted, grandma is more likely to fall on a level surface in her home rather than on the stairs, although it is helping grandma up and down stairs that the public seems to focus on.

Injury is a small specialty in epidemiology but an interesting one. Most “accidents” aren’t freak events but the result of something both foreseeable and preventable. Or to use a hoary cliché from the injury community, “Injuries are not accidents.”

Comments

  1. #1 Russell
    February 20, 2010

    Always keep one hand for yourself.

  2. #2 Lyle
    February 20, 2010

    I understand that is a rule on offshore oil platforms to keep one hand on the railing of stairs. I believe that homes should be required to have 2 hand rails on stairs not just one for safety also. I sometimes wonder why someone doesn’t develop a set of pads like football hip pads to pad the hip joint and distribute force over a larger area. If you think about it thats what the football hip pad does to prevent hip pointer and also hip fracture.

  3. #3 cmc
    February 20, 2010

    On sailboats we also ‘must’ keep one hand on the rail or stay or some other part of the boat in weather, and yes, two on the gangway always. On good boats this is followed without question by all . . .

    The hip padding idea has been tested in geriatrics research . . . apparently the device increased accidents due to encumberances.

    I suspect the increase in falls is due to meds AND lack of activity. And overweight. And alcohol or other substance use. I see people in early older age – late 50’s to early 60’s – who are already couchbound, or shall we say: TV bound. I’m originally from a farming area — most people in their 90’s were still spry and active. There is also an odd lack of situational awareness in many people nowdays and I am not sure if it is psychological or otherwise induced: ‘we are no here.’

    And then there are the unfortunate few who are helped down those stairs . . . .

  4. #4 revere
    February 20, 2010

    cmc: One of the competing or alternative hypotheses for increases in falls in the elderly is that they have become more active and hence increased their exposure to falling. It is a complex and confounded set of possible causes and covariates. Not my line of work, but very interesting.

  5. #5 cmc
    February 20, 2010

    Revere: Yes, I fully understand the competing hypotheses – I teach grad school research methods, epi postdoc. I was also a coach and from that perspective I observe a major lack of physical coordination of most people after the age of 55 or thereabouts, due — I assume — to lack of habitual physical activity. 2/3 of US adults are overweight – which contributes to the ungainlyness. So maybe an interaction effect: more active but lacking habitual conditioning and coordination-developing activity.

    People don’t have to be gym rats: there are many daily opportunities for people to move well — but parked in front of the telly is not good. Hunched over computers is not good also — that being my current problem . . .

  6. #6 Lyle
    February 20, 2010

    One of the factors is that we may be to agressive in blood pressure control leading to othostatic hypotension more than thought. Now that studies are begining to find that past 75 a number of the commonly held ideas are not as valid, I wonder if the target range of blood pressure might want to be raised there at least back to the old 100+your age number of the 1950s? The question to ask about the issue is the cure worse than the disease, just like now studies show that past 75 prostate cancer is best treated by watchful waiting, as one is more likley to die of something else.

  7. #7 cmc
    February 21, 2010

    Just now remembered a research study that found balance training reduces falls. Easiest daily form of bt is to stand one one foot – with a chairback under the hand in case the person gets tipsy. Several neuros said that balance stability is their quick&dirty indicator of neuro function — all at one med school so might be a local pearl.

    Pts have told me that bp meds make them dizzy — not my area, so I don’t know if it is true, but bp meds is not the best way to reduce bp over a long course. Reduced weight, increased exercise is.

  8. #8 MoM
    February 22, 2010

    Lyle: like now studies show that past 75 prostate cancer is best treated by watchful waiting, as one is more likely to die of something else.

    Which was the advice my father got when he got his prostate flared back up at 75 after being “TURPed” at age 60. He died at 95 of metastatic prostate cancer.

  9. #9 Paula
    February 22, 2010

    Dunno, but I’ve found that, in spite of being what is called “very active” for my age (late 60s-early 70s) and doing core and balance exercises regularly, no bp meds, I can no longer stand on one foot as I used to, effortlessly, when younger. Perhaps depends on spine and bone strength?

  10. #10 Jim Glinn
    February 24, 2010

    We have been looking at this for some time. We are a Team of physical therapists, athletic trainers, ex physiologists and care extenders. While the boomer population is more active they are also seem to have higher expectation of where/how they can be active.

    Regardless of age, the specific adaptations to the imposed demands law stand true. To get better at NOT falling practice not falling, work single leg activities, work the posterior chain and supporting muscles and proprioceptors.

    We developed this complimentary site to help with the problem: http://www.movementforlife.com

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