Sir,

We read with interest the article named 'Prevention and treatment of decompression sickness using training and in-water recompression among fisherman divers in Vietnam' that was published in Injury Prevention 2016 February issue. We want to share our opinion about some parts of the article, especially in three subjects.

It was mentioned that, the aim of the study was to investigate the impact of training programmes run over a period of 3 years, focusing on preventing DCS by reducing unsafe diving practices and treating DCS by means of IWR, in the last sentence of introduction. So we understood that the main subject of the study is forcing fisherman divers to make safe dives resulting in decrease in DCS and also to treat urgently with IWR if disease occurs. Therefore this education only involves lowering DCS and treating with IWR. But it is remarked as "Since implementing IWR training, annual mortality and morbidity incidence rates due to neurological DCS were reduced in our pilot sample" in second sentence of discussion. It was understood from the article, prior to 2009, annual mortality due to diving was estimated 4?1 cases per 1000 fisherman divers and annual incidence of DCS was 8?2 cases. Between 2009 and 2012 fatality rate dropped 1 per 1000 divers and annual incidence of DCS dropped 2?1 per 1000 divers. However we know it is unlikely to have a mortality rate of four cases in every eight DCS cases before 2009 and also one fatal case within two cases of DCS between 2009 and 2012. Many studies was reported before about this issue, in one of them Xu et al. showed nine deaths of 5278 consecutive DCS cases with a incidence of 0.17% in a decade (1). It seems suspicious that one in a two cases DCS mortality rate as mentioned in the article. Probably the mortality reasons must be other than DCS, e.g. drowning, nitrogen narcosis and diving related accidents, before 2009 and also between 2009 and 2012 in these dive sites. We found it very challenging; two days 10 subjects IWR training courses reduced annual mortality rates due to the DCS.

On the other hand, in the treatment of DCS, there appears three main goals; [1] immediate reduction in bubble size, [2] to increase the washout of inert gas and [3] to provide oxygen delivery to the tissues to restore normal functions (2). If we put an order in terms of treatment efficacy; standart recompression treatment in chamber (oxygen, 45-60 feet), IWR with oxygen, breathing oxygen at surface, IWR with air at working depth (fisherman divers' traditional IWR), IWR with air (Clipperton Protocol, 9 m.) had superiority each other, respectively in the treatment of DCS. It is well known that, in the absence of a hyperbaric chamber treatment, IWR with oxygen of course superior to breathing oxygen at surface in DCS. Known risks of IWR are drowning, applying difficulties, hypothermia and disability to transfer patient to chamber because of being underwater. It has been shown that IWR with air at 9 meters has no significant benefit in DCS; also authors mentioned in the article IWR with air is useless which the fisherman divers used to do traditionally. Nevertheless authors advised to divers apply IWR with air at nine meters, which is the last choice in treatment of DCS but they did not mention exactly why divers should follow this protocol. If it is done with oxygen it should be helpful but not with air. According to our knowledge IWR with air should not be performed, if it is to be done deep treatment protocols must be chosen, not at shallow depth like nine meters (3).

The last point we want to take attention is that only eight of 24 DCS patients have been treated with oxygen, the rest were treated with air. Unfortunately the number of divers, which were treated with oxygen, is very low. However, two of eight of these patients (%25) started with oxygen but continued with air, because the cases were not able to breathe from a second stage regulator. In our opinion, if the rate (%25) is really in high ranges like this, there could be given educations about using hoses without second stage regulator.

Declaration of conflicting interests: The authors declared no conflicts of interest with respect to the authorship and/or publication of this letter. Funding: No author or related institution has received any financial benefit for this letter.

References 1. Xu W1, Liu W, Huang G, Zou Z, Cai Z, Xu W. Decompression illness: clinical aspects of 5278 consecutive cases treated in a single hyperbaric unit. PLoS One. 2012;7(11):e50079. 2. Diving and Subaquatic Medicine, Fifth Edition. Carl Edmonds, Michael Bennett, John Lippmann, Simon Mitchell. 2015. p. 167 3. 6th ed. USA: U.S. Navy Diving Manual, 2008

Conflict of Interest:

None declared

Dear Editor

I read with interest this paper by Ozanne-Smith and co-workers.[1] I congratulate the authors on their meticulous confirmation of the intuitive expectation that fewer firearms in the community correlates with a reduction in firearms deaths and injuries. Unfortunately, the authors confine themselves to the limited objective of studying firearm deaths in isolation. They do not ask whether the reduction in firearm deaths has any influence on total deaths and injuries. They make only a single comment that “despite the declines related to homicide, overall suicide and homicide rates in Victoria did not show a similar decline.” However, review of the wider literature shows that changes in gun ownership are unrelated to total suicide and homicide rates.

I am concerned that political activist groups will take this study beyond its frame of reference and misquote it as proving that “gun bans work”. Some moral zealots of anti-gun persuasion have had an ongoing campaign of media advocacy to manipulate public opinion and policy on this issue, starting some years BEFORE the Port Arthur killings which were the catalyst for the Australian mass gun confiscations of 1996. This is mentioned repeatedly in the work by Chapman,[2] one of the references listed by the authors. Indeed, Chapman suggests such groups form a prior contingency plan to maximise politically advantageous media coverage of any dramatic gun crimes which may occur in the future.

Because of this controversy, it is vital that hard facts be obtained on the specific question of whether mass confiscation of legally owned guns causes a sustained and significant reduction in TOTAL suicide and homicide. Besides the AUS$340 million mentioned by Ozanne-Smith and co- workers, Australian taxpayers have paid another AUS$100 million for the 2003 handgun confiscations from legally licensed owners. This diverts valuable scarce resources from health, education and law enforcement. There is no point in paying huge sums to get people to hang themselves instead of shoot themselves and to stab each other instead of shoot each other.

We must check whether there is a net benefit to public health and safety. Resources for compensation payments and for enforcement costs must come from somewhere. If taken from the health sector, such bans may indirectly end up costing more lives than they might save. For example, over the relevant time, is there a correlation between declining gun deaths and lengthening hospital waiting lists or frequency of ambulance bypass? No-one has attempted such a difficult assessment, apart from Lott and Mustard, who examined only crime costs.[3] Australia cannot afford not to get this wrong.

Review of the wider literature shows:

1. The Australian Bureau of Statistics found a steady decline in all types of gun deaths over 15 years from 1980-1995, before the law changes.[4]

2. Australian total murder rates were lower prior to 1970, when there were virtually no long gun controls at all.[5] The long term homicide rate is fairly stable despite annual fluctuations.[6]

3. Guns now account for only 12% of Australian suicides[7] and only 16% of Australian murders.[8]

4. Ninety percent of Australian gun murders are committed by criminals who are unlicensed and with guns which are unregistered.[9] Ozanne-Smith’s hope of achieving “vision zero” through confiscation of registered guns from licensed owners is therefore naïve at best. (NOTE: Only legal guns were confiscated. The authors’ findings are irrelevant to 88% of total suicides, 90% of gun murders and over 98% of total murders.)

5. The National Injury Surveillance Unit documented that the fall in gun suicides was accompanied by a rise in total suicide due to substitution of hanging and car exhaust gas.[10]

6. Britain has suffered massive rises in gun murder and total murder, about 70% over 1996-2003, despite the total confiscation of all legal handguns in 1996-7.[11]

7. The USA has had a 50% fall in murder over a similar period,[12] despite increased gun ownership.[13] This is most marked in those states which allow guns for self defence.[14]

Readers should also be aware that some criminologists have made scathing criticisms of the quality of research done by medical doctors in this area, notably Kates et al.[15]

I look forward to further research from Professor Ozanne-Smith and the Monash group addressing the relationship between gun availability and total suicide and murder rates and also the cost-effectiveness of mass gun confiscation in reducing these deaths, both in Australia and other nations.

References

1. Ozanne-Smith J et al. Firearms related deaths: the impact of regulatory reform. Injury prevention 2004;10:280-286.

2. Chapman S. Over Our Dead Bodies: Port Arthur and Australia’s fight for gun control. Pluto Press 1998.

3. Lott JR, Mustard DB. Crime, Deterrence and Right-to Carry Concealed Handguns. Journal of Legal Studies. 26(1) 1-68 Jan 1997. URL direct link accessed 14 Nov 2004.

4. Firearms Deaths Australia. Australian Bureau of Statistics. Feb 1997. Cat. No. 4397.0

5. Mouzos J. Homicidal Encounters: a Study of Homicide in Australia 1989-1999. Australian Institute of Criminology 2000.

6. Mouzos J, Segrave M. Homicide in Australia 2002-2003 National Homicide Monitoring Program Annual Report. Australian Institute of Criminology 2004.

7. Year Book Australia 2002. Health Special Article-Suicide. Australian Bureau of Statistics. URL direct link accessed 29 Oct 2004.

8. Mouzos J., Segrave M. Homicide in Australia 2002-2003 National Homicide Monitoring Program Annual Report. p42. Australian Institute of Criminology 2004.

9. Mouzos J. Licensing and Registration Status of Firearms used in Homicide. Trends and Issues Paper 151. May 2000. Australian Institute of Criminology. URL direct link accessed 14 Nov 2004.

10. Harrison JE., Steenkamp M. Suicide in Australia: Trends and data for 1998. Australian Injury Prevention Bulletin Issue 23 2000. URL direct link accessed 14 Nov 2004.

11. Povey D. Ed. Crime in England and Wales 2002/2003: Homicide and Gun Crime. January 2004. Home Office –United Kingdom. URL direct link accessed 14 Nov 2004.

12. Homicide Trends in the US. Long term trends and patterns. US Department of Justice 2003. URL direct link accessed 14 Nov 2004.

13. Kleck G. Targeting Guns: Firearms and their Control. Table 3.1 pp 96-7. Aldine de Gruyter 1997.

14. Lott JR, Mustard DB. ibid.

15. Kates DB. Et al. Chapter 5, Bad medicine: Doctors and Guns. in “Guns: Who should have them?” Ed. Kopel DB. Prometheus 1995.

Dear Editor

I read the response from Chapman with interest.[1] In referring to the number of guns handed in during the 1996/97 buy back, Chapman fails to disclose that those firearms, legally owned by farmers and sporting shooters, had never been a problem in society. I refer to the submission by Australian Institute of Criminology to the publication "Evaluating Gun Policy: Effects on Crime and Violence" published by Brookings Institute Wash. USA, in which the topic of Australia's gun laws was covered under the heading of "A massive Buy Back of Low Risk Guns"!! Murder by firearm has always been a relatively rare occurence in Australia.

Since the harsh gun laws of 1996/97, contrary to Chapman's claims, there have been several mass murders; the Childers (QLD) Fire Massacre, in which 15 young backpackers were murdered, and the Snow Town (S.A.) "bodies in the barrels" case, in which 12 people were murdered (by piano wire!) as well as several cases where parents murdered their children (and sometimes themselves) by knife, bathwater, pillows and car exhaust. (ref. A.I.C. Research Report no 46).

The tragic mass murders, where a firearm was selected as the weapon, should have been treated as problems of mental health, not of firearms ownership! As long as mental health is ignored in our community, murders and suicides will continue to be a problem. Those in the medical profession, who choose to place the blame for such occurrences, on legally owned firearms, are simply diverting attention from the real issues.

On the topic of mobile telephones, I do not need to offer any supporting data, as reference was made to mobile telephone ownership, as an example of the many variables that should have been taken into account, in analysing what had happened since 1978. I might well have highlighted the increasing use of CCTV surveillance of shopping centres and railway stations, or of the dramatic increase in private security guards, armed with handguns, who now patrol our streets. All of the above, and many other factors, may have had an effect on "gun deaths" , but the original paper by Monash Uni Accident Prevention Unit, failed to take any of those factors into account.

Further study should also be made of the useage of firearms for self- defence. It can be assumed that if just one person at Port Arthur in 1996, had been carrying a firearm, the number of deaths might have been as low as 2 or 3, rather than 35.

References

1. Chapman S. No mass shootings in Australia since gun law reform [electronic response to Ozanne-Smith J, Ashby K, Newstead S, Stathakis V Z, Clapperton A. Firearm related deaths: the impact of regulatory reform] injuryprevention.com 2004 URL direct link to eLetter

Dear Editor

I note with interest Chapman's contribution to the discussion[1] on the paper by Ozanne-Smith et al. on firearm law reform in Australia.[2] Chapman's claims are not incorrect, as far as they go. However, like Ozanne-Smith et al, it is what Chapman has left out that may confuse readers.

There have been several mass murders (defined as four or more deaths in one incident) in Australia since 1996, although none with guns. The worst was the arson attack in Childers, where 15 people were murdered. Others have involved knives and parents gassing themselves and their children in their cars.

The effectiveness of the 1996 Australian gun confiscations ("buy- back" is a Government euphemism) in reducing suicide and violent crime has been examined in detail by Reuter and Mouzos.[3] They find, inter alia, that:

1. Mass murders account for only 3% of all Australian homicides.[4] Of the 13 such killings 1989-90 to 1996-7, only six involved guns.[5] (Chapman's comments are simply irrelevant to over 98% of Australian murders).

2. "Observed declines in ... homicide continued a long term trend rather than the effects of the Port Arthur incident."[6]

3. On mass murder, as raised specifically by Chapman, they state "there has been a modest reduction in severity and frequency ... none have involved firearms, although the frequency of these events is so low that not much can be inferred".[7]

4. The lowest Australian gun homicide rate was in 1950,[8] (when there were no virtually long gun controls at all).

5. "Suicide rates did not fall ... homicides continued a modest decline."[9]

6. There was a marked rise in total armed and unarmed robbery, particularly with knives.[10]

7. UK gun bans did not reduce violent crime.[11]

8. "All this is generally consistent with substitution."[12]

The most enthusiastic endorsement Reuter and Mouzos can scrape together is "There may have been a modest effect on homicides. The number declined continuing a pre-existing trend ... one could not reject the hypothesis that it had reduced homicides by 10%."[13] (As the homicide rate before the 1996 confiscations fluctuated by up to 15% each year,[14] this is not significant). While Reuter and Mouzos do not say so, their findings suggest that the 1996 confiscations have wasted over half a billion dollars of Australian taxpayers' money.

Chapman attributes the passage of the 1996 Australian confiscation laws NOT to hard facts, or any plausible theory, but to years of prior media advocacy extending over several years BEFORE the Port Arthur killings.[15] He further urges that such tragedies be "anticipated and planned for" by such activists to "exploit to advantage" the interest generated.[16]

Chapman is well known for his enthusiastic use of media advocacy to bring about changes in the law and teaches tertiary courses on this subject.[17]

Details of technique are provided in his outstanding text,[18] which is essential reading for political activists of all persuasions. Despite the reference to public health in the title, the book is about media manipulation, with minimal reference to public health principles. There is nothing on relative risk, cost-benefit analysis, correlation versus causation or outcome evaluation. There is no matching insistence on checking actual outcome of the law changes. In particular, Chapman insists the activist must " frame the debate".[19] In our current context, this means insisting that we are concerned only with gun murders, not total murders. He also recommends the use of "creative epidemiology" in advocacy work, ie reworking the data into "interesting and arresting forms."[20] He actually does this in his electronic letter where he compares 103 months with 9 years. Chapman describes how to facilitate misrepresentation of extremist opposing views as being typical of moderate mainstream opposing views.[21]

Many will doubt whether such a simplistic "sound bite"[22] approach is likely to improve public safety. Browning, in particular, claims that political activists dress their agendas in public health clothes so as to claim respectability, moral superiority and sometimes government funds.[23] In addition, the mass media may well be part of the problem. Criminologists have repeatedly pointed out the media practice of concentrating on rare sensational events, thus misleading the public about crime risks in the real world.[24-26]

It would be very helpful if Chapman and Ozanne-Smith could EITHER publicly clarify why they believe gun deaths are of much greater importance than non-gun suicides and murders OR confirm that the real issue is how to reduce TOTAL deaths, not just deaths from a particular instrument. We must decide whether the aim is to reduce deaths ONLY from GUN murders and suicides or deaths from total murders and suicides. Given limited resources, what is the best way to use them?

Conclusions: 1) The 1996 mass gun confiscations were not nearly as effective as Chapman implies, if they were effective at all; 2) all political activists should study Chapman's book on media advocacy; and 3) the subtle distinction between "media advocacy" and propaganda, if any, is unclear and readers may wish to ponder for this for themselves.

I have previously detailed the failure of mass gun confiscation in both Australia and the United Kingdom to bring about any significant change in total homicide rates.[27]

References

1. Chapman S. No mass shootings in Australia since gun law reform [electronic response to Ozanne-Smith J, Ashby K, Newstead S, Stathakis V Z, Clapperton A. Firearm related deaths: the impact of regulatory reform] injuryprevention.com 2004 URL direct link to eLetter .

2. Ozanne-Smith J et al. Firearms related deaths: the impact of regulatory reform. Injury prevention 2004;10:280-286.

3. Reuter P, Mouzos J. "Australia: a Massive Buyback of Low-Risk Guns".Chapter 4. In: "Evaluating Gun Policy- Effects on crime and violence". Eds. Ludwig J, Cook P J. Brookings Institute Press, 2003.

4. ibid. p127

5. ibid. p127

6. ibid. p134

7. ibid. p122

8. ibid. p126

9. ibid. p121

10. ibid. p138

11. ibid. p122

12. ibid. p140

13. ibid. p140

14. Mukherjee S, Carcach C. "Violent Deaths & firearms in Australia: data and Trends". Australian Institute of Criminology 1996. Derived from Table 3.1, p18.

15. Chapman S. "Over Our Dead Bodies-Port Arthur and Australia's fight for gun control". Pluto Press 1998. Preface vii, pp 5,8,9. NOTE: This book may be out of print. Contact Pluto Press Australia (not Pluto UK) pluto@plutoaustralia.com

16. Chapman S. Over our dead Bodies. ibid. pp 6,7.

17. http://tobacco.health.usyd.edu.au/site/supersite/contact/docs/chapman.htm

18. Chapman S, Lupton D. "The Fight for Public Health-Principles and practice of media advocacy". BMJ Publishing Group 1994.

19. Chapman & Lupton. Ibid. p12

20. ibid. p160-163

21. ibid pp158-9.

22. Chapman S. Over Our Dead Bodies op. cit. p90.

23. Browning RW. "Exploiting Health-Activists and Government v the people". Canonbury Press 1992. Pp 3,4,13.

24. Mouzos J., Segrave M. "Homicide in Australia. 2002-2003 National Homicide monitoring program Annual Report". Australian institute of criminology 2004. p3.

25. Weatherburn D. "Law and Order in Australia-Rhetoric and reality". The Federation Press 2004. pp 2,3,48

26. Grabowsy P., Wilson P. "Journalism and Justice-How crime is reported". Pluto Press Sydney. 1989. Especially chapters 2,8,9.

27. Lawson J B. Re: Firearm related deaths: the impact of regulatory reform. [electronic response to Ozanne-Smith J, Ashby K, Newstead S, Stathakis V Z, Clapperton A. Firearm related deaths: the impact of regulatory reform] injuryprevention.com 2004 URL direct link to eLetter