Injury Rates among divers...The DAN report

[sharpenu]

In a couple of other threads, there were some questions about the injury rates in divers and the differences between injuries for technical vs recreational diving. I have been working on a paper analyzing the differences between recreational vs technical diving and DIR vs the general population in terms of injury and death rates. I have found some interesting facts. The paper is not yet complete, but I can shed some light on injuries. All numbers are for the year 2000. (The latest year for which facts were available)

In the US and Canada 1024 divers were recompressed and there were 91 dive related fatalities. Stats as follows:

the #1 injury was numbness/tingling (mild neuro deficit)

those in their 30's were the age group with highest reported injuries

Technical divers represented 8% of injuries and 20% of fatalities

3% of injuries and 13% of fatalities occured during technical dives

More than half of all injuries and 2/3 of fatalities occured in divers with less than 20 logged dives during the 12 moinths preceeding the injury

90% of injuries, 77% of fatalities occured in Salt Water

The interesting figure here is that even though technical divers represented 8% of the injured divers, only 3% of the injuries occured during technical dives. That would seem to indicate technical divers "letting their guard down" during what is perceived to be an "easy" recreational dive. The fatality figures also reflect this. The message here is that NO dive is routine and complacency kills.

Also note that most of the injuries/fatalities occured in infrequent or beginning divers. Does that mean "dive more=hurt less" or does it mean that most divers dive less than 20 per year, which throws off the figures?

 

[jbd]

Interesting post. Thanks.

As for the last paragraph, it seems that frequency and recency(sp?) are important factors in diving safe. Of those in this group with high incident rates, I wonder how many were dives involving two new divers as a buddy team instead one new person paired with a more seasoned diver? Would that be discernable?

 

[Lost Yooper]

You should find out what percentage of the active diving population are considered "technical divers" and what percentage of dives being done are technical dives. That'll be tricky. Then find out what percentage of the technical diving fatalities were divers using air for their bottom gas -- especially in that 13% catagory. What is a technical dive? Does that include any overhead dive, either solid or imaginary (deco ceiling)? It would be nice to see a break down of that.

Mike

 

[Rick Murchison]

Statistics must be carefully scrutinized to get anything meaningful out of them, and these are no exception...
(1) "those in their thirties were the age group with the highest reported injuries" may mean nothing more than "those in their thirties make up the largest group of divers." I don't know - but my casual observations around the places I dive make this particular "statistic" meaningless for that reason.
(2) "Technical divers represented 8% of injuries and 20% of fatalities" An almost totally useless statistic on the face of it. What is a "technical diver?" I do cave diving, and that's technical - but my "technical" dives are a very small percentage of my total dives - probably about one in twenty (5%). How many of the total dives done are done by "technical divers?" If more than 8% then this stat means technical divers are less likely to get injured than the general diving population - if less than 8% they're more likely to get injured... The 20% only becomes meaningful when the 3%/13% numbers from the next bullet are considered - removing those, we have a stat that reads something like "5% of injuries and 7% of fatalities were to "technical divers" doing "recreational dives" - with less than a hundred total deaths this statistic loses any significance at all, especially considering the likelihood that a "technical" diver's typical "recreational" dive is going to come closer to the corners of the "recreational" envelope. Again, I conclude that this statistic is without significance.
(3) "3% of injuries and 13% of fatalities occured during technical dives" - this one is more likely meaningful. First, a "technical diver" doing a "recreational dive" is not considered in the group. It is likely that "recreational divers" attempting "technical dives" are included in the statistic and likely represent a portion of the injuries here that far exceed their percentage of participation in "technical" dives. My feeling is that "technical dives" make up far less than 3% of all dives, and that therefore the 3% represents a significantly higher mishap rate for technical versus recreational dives, but without knowing for sure it's still just a guess. The 13% is quite clear, I think. The 13% is the one truly meaningful number of the whole bunch - and means that an injury suffered on a "technical" dive is far more likely to be fatal than an injury suffered on a "non-technical" dive. A prime example of this is getting lost. Getting lost in the open water yields a statistic of one embarrassed diver, no injury, while getting lost in a cave or wreck gives us one injury, and the injury is death. But I still have to make some assumptions on what these statistics really mean to get anything useful out of them. It is also useful to remember that 13% means precisely 12 deaths. Now some meaningful numbers would be to know how many of the twelve weren't trained for the dive they were on? And how many of the twelve were trying to set some record? And removing those, how does the risk of a technical dive stack up? The bullet of 3% and 13% doesn't mean so much after all...
(4) The last two bullets most likely reflect the "where" and the "who" of diving. More than half don't have more than 20 dives in the last 12 months and 90% of dives are in salt water. If that's the case indeed then those statistics have zero significance, too.
-------------------
Bottom line - the only significant gem I can extract with reasonable certainty is that if a diver gets injured on a technical dive then it's more likely to be a fatal injury than if it's a recreational dive.
Wow! Who'd a thunk it?

Rick

 

[Wendy]

Also what percentage of deaths occured in technical dive environments by divers not trained for that kind of diving.

 

[Lost Yooper]

Lot's of work to do, eh?



Mike

 

[devilfish]

This may be off the wall, but I always wondered how many divers developed DCI, did not report because of many reasons one of them may be lack of knowledge and denial. Because of that condition three days later got a heart attack and it was never associated with diving.

 

[sharpenu]

1 Many people confuse FACTS with STATISTICS. A fact is a reported, verifiable number. A statistic is when facts are used to mathematically predict the outcome of an event. Example: A fact is: of the 91 divers reported killed, 20% were technical divers. A statistic would be: 20% of all divers killed are technical divers. I did not attempt to compute a statistical analysis of the data, as one year's data in itself is not sufficient for statistical purposes. (Example- last year nearly 400 firefighters were killed in New York. That does not mean that that may be used in any statistical data, unless a trend were to develop.)The data presented here were FACTS, not statistics.

2 I did not try to define terms here. If you want the definition, I used the standard ones that are being used by DAN and others. I did not intend to get into a semantic, hair splitting arguement.

3 As the subject line implies, the report from which I got most of this data comes from DAN. It was a 123 page report. I don't have the room or time to discuss every page here. You may download it from them if you wish. There are also COMPLETE written reports of each fatality there.

If Rec divers are a part of the Tec diving fatality report, that would tend to skew the figures even more in the direction of making my point. It would lower the incidence of Tec divers injured on Tec dives, making the disparity even more evident.

This was a report of deaths and injuries requiring decompression. Who knows how many cases of sinus squeeze or unreported cases of DCS/DCI there are.

The year 2000 report is not presented nor is it sufficient to draw conclusions from. It IS, however a data point which we can all learn from.

 

[Rick Murchison]

Originally posted by sharpenu
1 Many people confuse FACTS with STATISTICS. A fact is a reported, verifiable number. A statistic is when facts are used to mathematically predict the outcome of an event. Example: A fact is: of the 91 divers reported killed, 20% were technical divers. A statistic would be: 20% of all divers killed are technical divers. I did not attempt to compute a statistical analysis of the data, as one year's data in itself is not sufficient for statistical purposes. (Example- last year nearly 400 firefighters were killed in New York. That does not mean that that may be used in any statistical data, unless a trend were to develop.)The data presented here were FACTS, not statistics.

2 I did not try to define terms here. If you want the definition, I used the standard ones that are being used by DAN and others. I did not intend to get into a semantic, hair splitting arguement.

3 As the subject line implies, the report from which I got most of this data comes from DAN. It was a 123 page report. I don't have the room or time to discuss every page here. You may download it from them if you wish. There are also COMPLETE written reports of each fatality there.

If Rec divers are a part of the Tec diving fatality report, that would tend to skew the figures even more in the direction of making my point. It would lower the incidence of Tec divers injured on Tec dives, making the disparity even more evident.

This was a report of deaths and injuries requiring decompression. Who knows how many cases of sinus squeeze or unreported cases of DCS/DCI there are.

The year 2000 report is not presented nor is it sufficient to draw conclusions from. It IS, however a data point which we can all learn from.

No one is attacking you, sharpenu... all you did was post the numbers, for which we are grateful. You also made some points on the difficulty of extracting the facts from the statistics, for which we are also grateful.
"You done real good."
Rick

 

[sharpenu]

Yooper-

I have attempted to find out what percentage of the total dive population is tech certified I asked the question "How many divers have been certified through your agency?" . However NAUI has not answered my query and the only answer I got from GUE was :"That is proprietary information which we cannot divulge."

Attempting to analize these numbers in any statistical sence will prove impossible due to the inability to determine if the sample is representative.