Injury estimates and a question of "should"

We've seen a lot of numbers over the past few posts. Over 200,000 playground injury hospitalizations per year, with who-knows-how-many skinned knees, bumped heads, and twisted ankles NOT taken for emergency room treatment, and therefore absent from the data. It's important to recognize that this 200,000 figure is a lower bound on the actual number of playground-related injuries; these are just the injuries that are taken for emergency room treatment.

What are these non-reported injuries? It stands to reason that there will be two such categories: injuries for which the child COULD or SHOULD be taken to the ER but isn't, and injuries that don't merit hospital treatment. Let's take them one at a time.

What would prevent a parent or educator from taking a child to the hospital for a bad injury? Not much, I'd wager. If a child gets badly cut, or breaks a bone, or is knocked unconscious, then I'm sure that he or she'd be taken to the hospital, health insurance or no health insurance. But what about a bump to the head, or a twisted ankle, or a not-too-bad cut? Here, there's some latitude for parents to opt not to take the kid to the ER and the decision will depend solely on the characteristics of the parent than anything else. Some parents would consider them hospital-worthy, some wouldn't. Call these Type I non-reported injuries.

What about the everyday bumps, bruises, and falls that comprise a childhood? There are not hospital-worthy injuries, and hardly even qualify as injuries. Let's call them Type II non-reported injuries.

So, now we can arrive at an estimate of total playground injuries:

Hospital visits + Type I injuries + Type II injuries

Now, how to estimate Type I and II injury rates? Is there any way of getting a tally on how many on these minor and unreported injuries happen each year? Well... not really. One COULD assign investigators to monitor a random sample of playgrounds all over the country for a certain period (say, 1,000 playgrounds for 2 weeks each), and have the monitors record every fall, bump, and scrape that happens, but I can't imagine the NSF dishing out grant money for that particular project. Alternatively, one could send out questionnaires to a random sample of schools asking that THEY monitor their playgrounds and record everything that happens, but there would be serious issues of selection bias to consider.

So, getting a total figure is probably impossible. Should we even try? I don't worry too much about the Type II injuries - they're unavoidable, and kids learn important lessons in spatial awareness and physical coordination by occasionally tripping over their own two feet. But I DO worry about the Type I injuries, and the differential rates of reportage. Does the NEISS data systematically under- or over-report certain types of injuries for certain groups of children (for example, injuries incurred at day care centers) because of characteristics of the parents (to use that same example, child at day care = parents working = probably have insurance = hospital visits)? And, if so, will that be taken into consideration for any regulations made from NEISS data?

In the same vein, I leave you with a link to an interesting report from the Harvard School of Public Health on the relationship between neighborhood socioeconomic characteristics and access to safe playgrounds in Boston. The authors conclude that "playground safety and access to playgrounds varied according to indicators of small-area socioeconomic and racial/ethnic composition." Not groundbreaking for anyone who has ever spent any time in a city, but still an interesting read.