Formulating policies and procedures for managing diving related deaths: a whole of state engagement from frontline and hospital services in Tasmania.

Introduction: Tasmania is a small island state off the southern edge of Australia where a comparatively high proportion of the 558,000 population partake in recreational or occupational diving. While diving is a relatively safe sport and occupation, Tasmania has a significantly higher diving death rate per head of population than other States in Australia (four times the national diving mortality rate). Methods: Three compressed gas diving deaths occurred in seven months between 2021-2022 prompting a review of the statewide approach for the immediate response of personnel to diving-related deaths. The review engaged first responders including the Police Marine and Rescue Service, hospital-based departments including the Department of Hyperbaric and Diving Medicine, and the mortuary and coroner's office. Results: An aide-mémoire for all craft groups, digitalised checklists for first responders (irrespective of diving knowledge), and a single-paged algorithm to highlight inter-agency communication pathways in the event of a diving death were designed to enhance current practices and collaboration. Conclusions: If used, these aids for managing diving related deaths should ensure that time-critical information is appropriately captured and stored to optimise information provided for the coronial investigation.

The effect of the perfluorocarbon emulsion Oxycyte™ in an ovine model of severe decompression illness.

Background: The treatment of decompression sickness (DCS) with hyperbaric oxygen (HBO2) serves to decrease intravascular bubble size, increase oxygen (O2) delivery to tissue and enhance the elimination of inert gas. Emulsified perfluorocarbons (PFC) combined with breathing O2 have been shown to have similar effects animal models. We studied an ovine model of severe DCS treated with the intravenous PFC Oxycyte™ while breathing O2 compared to saline control also breathing O2. Methods: Juvenile male sheep (N=67; weight 24.4±2.10kg) were compressed to 257 feet of sea water (fsw) in our multiple large-animal chamber where they remained under pressure for 31 minutes. Animals then were decompressed to surface pressure and randomized to receive either Oxycyte at 5mL/kg intravenously (IV) or 5mL/kg saline IV (both receiving 100% O2) 10 minutes after reaching surface pressure. Mortality was recorded at two hours, four hours, and 24 hours after receiving the study drug. Surviving animals underwent perfusion fixation and harvesting of the spinal cord at 24 hours. Spinal cord sections were assessed for volume of lesion area and compared. Results: There was no significant difference in survival at two hours (p=0.2737), four hours (p=0.2101), or 24 hours (p=0.3171). Paralysis at 24 hours was not significantly different. However, spinal cord lesion area was significantly smaller in the Oxycyte group as compared to the saline group, with median spinal cord lesion areas 0.65% vs. 0.94% (p=0.0107). Conclusion: In this ovine model of severe DCS the intravenous PFC Oxycyte did not reduce mortality but did ameliorate spinal cord injury when used after the onset of DCS.

Lessons from a historic example of diving safety rules violation: the case of Greek sponge divers.

This study presents a historical example of systematic safety rules violations by professional sponge divers in Greece during the early 20th century. In light of absolute unaccountability in favour of economic competition and in the absence of state oversight, the profession of sponge diving had developed into a deadly undertaking. The study is based on a report compiled by Professor of Hygiene and Microbiology Konstantinos Savvas, which was addressed to the Ministry of Marine Affairs. Savvas' report rested on data concerning hospitalised divers derived from the medical records of warship 'Kriti' (Crete), which escorted groups of Greek fishing vessels to four of their expedition in the Mediterranean over the period 1900-1903. Although the events explored herein took place at a time much different from the modern era with its numerous advancements in hyperbaric medicine, enhanced divers' professionalism and the establishment of labour rights and strict safety regulations, we should not overlook the human factor of professional exploitation that leads to the violation of safety rules. On the other hand, supervisory authorities entrusted with the responsibility of overseeing professional activities ought to be vigilant on a constant basis, especially in times of economic crisis that may lead to lax state functioning.

Perfluorocarbon in Delayed Recompression with a Mixed Gender Swine Model of Decompression Sickness.

INTRODUCTION: Perfluorocarbons (PFC) are fluorinated hydrocarbons that dissolve gases to a much greater degree than plasma and hold promise in treating decompression sickness (DCS). The efficacy of PFC in a mixed gender model of DCS and safety in recompression therapy has not been previously explored. METHODS: Swine (25 kg; N = 104; 51 male and 53 female) were randomized into normal saline solution (NSS) or PFC emulsion treatment groups and subjected to compression on air in a hyperbaric chamber at 200 fsw for 31 min. Then the animals were decompressed and observed for signs of DCS. Afterwards, they were treated with oxygen and either PFC (4 cc · kg-1) or NSS (4 cc · kg-1). Surviving animals were observed for 4 h, at which time they underwent recompression therapy using a standard Navy Treatment Table 6. After 24 h the animals were assessed and then euthanized. RESULTS: Survival rates were not significantly different between NSS (74.04%) and PFC (66.67%) treatment groups. All swine that received recompression treatment survived to the end of the study and no seizures were observed in either PFC or NSS animals. Within the saline treated swine group there were no significant differences in DCS survival between male (75.00%, N = 24) and female (73.08%, N = 26) swine. Within the PFC treated swine, survival of females (51.85%, N = 27) was significantly lower than males (81.48%, N = 27). DISCUSSION: In this large animal mixed gender efficacy study in DCS, PFC did not improve mortality or spinal cord injury, but appears safe during recompressive therapy. Gender differences in DCS treatment with PFC will need further study.Cronin WA, Hall AA, Auker CR, Mahon RT. Perfluorocarbon in delayed recompression with a mixed gender swine model of decompression sickness. Aerosp Med Hum Perform. 2018; 89(1):14-18.

Metabonomic potential plasma biomarkers in abnormal fast buoyancy ascent escape-induced decompression sickness model and the protective effects of pyrrolidine dithiocarbamic acid.

BACKGROUND: Decompression sickness (DCS) induced by fast buoyancy ascent escape (FBAE) is a special DCS, characterized with cardiopulmonary injuries. Serum metabonomics of this type of DCS has not yet been studied. We proposed a metabonomics approach for assessing serum metabonomics changes and evaluating the preventive effect of pyrrolidine dithiocarbamic acid (PDTC) in FBAE-induced DCS rats. METHODS: Sixty-five (65) rats were divided into three groups, including the Control, DCS and PDTC groups. After receiving physiological saline or PDTC pretreatment, rats in the DCS and PDTC groups received the same protocol of simulated FBAE. Following this, a metabonomics approach - combined with pattern recognition methods including PCA and PLS-DA - was used to characterize the global serum metabolic profile on survival rats (five rats per group) associated with abnormal FBAE-induced DCS. As the VIP-value threshold cutoff of the metabolites was set to 2, metabolites above this threshold were filtered out as potential target biomarkers. RESULTS: Sixteen (16) distinct potential biomarkers in rat plasma were identified. PDTC significantly lowered DSC mortality from 60% to 10%, and alleviated ultrastructural alteration of the left ventricular apex compared to the DCS group. It was found that abnormal FBAE-induced DCS was closely related to disturbed fatty acid metabolism, glycerophospholipid metabolism, sterol lipid metabolism, and bile acid metabolism. With the presented metabonomic method, we systematically analyzed the protective effects of PDTC. CONCLUSION: The results demonstrated that PDTC administration could provide satisfactory effects on abnormal FBAE-induced DCS through partially regulating the perturbed metabolic pathways.

Possible central nervous system oxygen toxicity seizures among US recreational air or enriched air nitrox open circuit diving fatalities 2004-2013.

BACKGROUND: The first diver certification programme for recreational 'enriched air nitrox' (EAN) diving was released in 1985. Concerns were expressed that many EAN divers might suffer central nervous system (CNS) oxygen toxicity seizures and drown. METHODS: US fatalities on open-circuit scuba occurring between 2004-2013, where the breathing gas was either air or EAN, were identified. Causes of death and preceding circumstances were examined by a medical examiner experienced in diving autopsies. Case notes were searched for witnessed seizures at elevated partial pressures of oxygen. RESULTS: The dataset comprised 344 air divers (86%) and 55 divers breathing EAN (14%). EAN divers' fatal dives were deeper than air divers' (28 msw vs 18 msw, p < 0.0001). Despite this, of the 249 cases where a cause of death was established, only three EAN divers were considered to have possibly died following CNS oxygen toxicity seizures at depth (ppO2 132, 142 and 193 kPa). CONCLUSION: The analysis of recreational diving fatalities in the US over 10 years found just one death likely from CNS oxygen toxicity among EAN divers. A further two possible, although unlikely, cases were also found. Fears of commonplace CNS oxygen toxicity seizures while EAN diving have not apparently been realized.

A rat model of chronic moderate alcohol consumption and risk of decompression sickness.

INTRODUCTION: This study aimed to establish if chronic, moderate, pre-dive alcohol consumption had any affect upon susceptibility to decompression sickness (DCS) in rats. METHODS: A treatment group of 15 rats were given water containing 12 mL ·L ⁻¹ of ethanol for four weeks. Controls (n = 15) were given water. Both groups were compressed with air to 1,000 kPa, followed by staged decompression. An additional 30 control rats from a similar previous experiment were added, raising the control-treatment ratio to 3:1. RESULTS: Rats in the treatment group consumed the equivalent of an 80 kg man drinking 2 L of 5 % alcohol by volume beer per day, which is three times the recommended daily limit for men. Overall, comparing the treatment group with the combined control groups neither weight (P = 0.23) nor alcohol consumption (P = 0.69) were associated with DCS. DISCUSSION: We observed that chronic, moderate alcohol consumption prior to compression was neither prophylactic nor deleterious for DCS in young, male rats.

Expression changes of inflammatory factors in the rat lung of decompression sickness induced by fast buoyancy ascent escape.

Fast buoyancy ascent escape is one of the major naval submarine escape maneuvers. Decompression sickness (DCS) is the major bottleneck to increase the depth of fast buoyancy ascent escape. Rapid decompression induces the release of inflammatory mediators and results in tissue inflammation cascades and a protective anti-inflammatory response. In our previous study, we found that DCS caused by simulated fast buoyancy ascent escape could induce acute lung injury (ALI) and the expression changes of the proinflammatory cytokines: tumor necrosis factor alpha (TNF-α), interleukin (IL)-1ß and IL-6 in rat lung tissue. In order to study the expression change characteristics of TNF-α, IL-1ß, IL-6, IL-10 and IL-13 in the rat lung of DCS caused by simulated fast buoyancy ascent escape, we detected the rat lung mRNA and protein levels of TNF-α, IL-1ß, IL-6, IL-10 and IL-13 at 0.5 hour after DCS caused by simulated fast buoyancy ascent escape (fast escape group), compared with the normal control group (control group) and diving DCS (decompression group). We observed that DCS caused by simulated fast buoyancy ascent escape could increase the mRNA levels of TNF-α, IL-1ß, IL-6, IL-10, and the protein levels of TNF-α, IL-10 in rat lung tissue. At the same time, we found that the protein level of IL-13 was also downregulated in rat lung tissue. TNF-α, IL-10 and IL-13 may be involved in the process of the rat lung injury of DCS caused by simulated fast buoyancy ascent escape. In conclusion, the expression changes of inflammatory factors in the rat lung of DCS caused by simulated fast buoyancy ascent escape were probably different from that in the rat lung of diving DCS, which indicated that the pathological mechanism of DCS caused by simulated fast buoyancy ascent escape might be different from that of diving DCS.

Dodecafluoropentane (DDFPe) and decompression sickness-related mortality in rats.

INTRODUCTION: Perfluorocarbon (PFC) formulations can be a useful adjunct treatment for decompression sickness (DCS) when staged decompression procedures cannot be followed due to time constraints or lack of equipment. The benefit of PFC treatment is believed to result from its ability to transport more dissolved gas than can be transported by blood alone. Dodecylfluoropentane (DDFPe) is a unique nanodroplet compound that expands into a gaseous state when exposed to physiological temperatures, resulting in a higher dissolved gas-carrying capacity than standard PFC formulations. METHODS: We investigated the efficacy of DDFPe in reducing morbidity and mortality in a rat model of severe DCS. Male Sprague-Dawley rats (250-280 g) were compressed to 210 fsw for 60 min before rapid decompression. Animals were immediately injected with 2% DDFPe (0.07 ml · kg(-1), 0.5 ml · kg(-1), 1.0 ml · kg(-1)) or saline, and were transferred to a 100% O2 environment for 30 min. RESULTS: Of the animals in the saline group, 47% (18/38) did not survive the decompression event, while ~98% (46/47) of the animals in the DDFPe group did not survive. Of the animals that died during the observation period, the saline group survived on average 89% longer than DDFPe treated animals. Seizures occurred in 42% of the DDFPe group vs. 16% in the saline group. Histological analysis revealed the presence of large, multifocal gas emboli in the liver and heart of DDFPe treated animals. CONCLUSIONS: We conclude that DDFPe is not an effective nonrecompressive treatment for DCS in rodents. Sheppard RL, Regis DP, Mahon RT. Dodecafluoropentane (DDFPe) and decompression sickness-related mortality in rats.

Effect of nitric oxide on spinal evoked potentials and survival rate in rats with decompression sickness.

Nitric oxide (NO) releasing agents have, in experimental settings, been shown to decrease intravascular nitrogen bubble formation and to increase the survival rate during decompression sickness (DCS) from diving. The effect has been ascribed to a possible removal of preexisting micronuclei or an increased nitrogen washout on decompression through augmented blood flow rate. The present experiments were conducted to investigate whether a short- or long-acting NO donor [glycerol trinitrate (GTN) or isosorbide-5-mononitrate (ISMN), respectively] would offer the same protection against spinal cord DCS evaluated by means of spinal evoked potentials (SEPs). Anesthetized rats were decompressed from a 1-h hyperbaric air dive at 506.6 kPa (40 m of seawater) for 3 min and 17 s, and spinal cord conduction was studied by measurements of SEPs. Histological samples of the spinal cord were analyzed for lesions of DCS. In total, 58 rats were divided into 6 different treatment groups. The first three received either saline (group 1), 300 mg/kg iv ISMN (group 2), or 10 mg/kg ip GTN (group 3) before compression. The last three received either 300 mg/kg iv ISMN (group 4), 1 mg/kg iv GTN (group 5), or 75 µg/kg iv GTN (group 6) during the dive, before decompression. In all groups, decompression caused considerable intravascular bubble formation. The ISMN groups showed no difference compared with the control group, whereas the GTN groups showed a tendency toward faster SEP disappearance and shorter survival times. In conclusion, neither a short- nor long-acting NO donor had any protective effect against fatal DCS by intravenous bubble formation. This effect is most likely due to a fast ascent rate overriding the protective effects of NO, rather than the total inert tissue gas load.

Postmortem CT appearance of gas collections in fatal diving accidents.

OBJECTIVE. The purpose of our study was to define the postmortem CT semiology of gas collections linked to putrefaction, postmortem "off-gassing," and decompression illness after fatal diving accidents and to establish postmortem CT diagnostic criteria to distinguish the different causes of death in diving. SUBJECTS AND METHODS. A 4-year prospective study was conducted including cases of death during diving. A hyperbaric physician analyzed the circumstances of death and the dive profile, and an autopsy was performed. Subjects were divided into three groups according to the analysis from their dive profile: decompression illness, death after decompression dive without decompression illness, and death after nondecompression dive without decompression illness. Full-body postmortem CT was performed before autopsy. RESULTS. The presence of intraarterial gas associated with death by decompression illness had a negative predictive value (NPV) of 100%, but the positive predictive value (PPV) was only 54% because of postmortem off-gassing. The PPV reached 70% when considering pneumatization of the supraaortic trunks. Pneumothorax, subcutaneous emphysema, and intraarterial gas, all of which are classic criteria for decompression illness diagnosis, are not specific for decompression illness. CONCLUSION. This study is the first to show that pneumothorax, subcutaneous emphysema, and intraarterial gas, all of which are classic criteria for decompression illness diagnosis, are not specific for decompression illness. Complete pneumatization of supraaortic trunks is the best postmortem CT criteria to detect a fatal decompression illness when CT is performed within 24 hours after death.

Recent modifications to the investigation of diving related deaths.

The investigation of deaths that involve diving using a compressed breathing gas (SCUBA diving) is a specialized area of forensic pathology. Diving related deaths occur more frequently in certain jurisdictions, but any medical examiner or coroner's office may be faced with performing this type of investigation. In order to arrive at the correct conclusion regarding the cause and manner of death, forensic pathologists and investigators need to have a basic understanding of diving physiology, and should also utilize more recently developed technology and ancillary techniques. In the majority of diving related deaths, the cause of death is drowning, but this more often represents a final common pathway due to a water environment. The chain of events leading to the death is just as important to elucidate if similar deaths are to be minimized in the future. Re-enactment of accident scenarios, interrogation of dive computers, postmortem radiographic imaging, and slight alterations in autopsy technique may allow some of these diving related deaths to the better characterized. The amount and location of gas present in the body at the time of autopsy may be very meaningful or may simply represent a postmortem artifact. Medical examiners, coroners, and forensic investigators should consider employing select ancillary techniques to more thoroughly investigate the factors contributing a death associated with SCUBA diving.

Analytic gain in probabilistic decompression sickness models.

Decompression sickness (DCS) is a disease known to be related to inert gas bubble formation originating from gases dissolved in body tissues. Probabilistic DCS models, which employ survival and hazard functions, are optimized by fitting model parameters to experimental dive data. In the work reported here, I develop methods to find the survival function gain parameter analytically, thus removing it from the fitting process. I show that the number of iterations required for model optimization is significantly reduced. The analytic gain method substantially improves the condition number of the Hessian matrix which reduces the model confidence intervals by more than an order of magnitude.

Dive-related fatalities among tourist and local divers in the northern Croatian littoral (1980-2010).

BACKGROUND: The aim of the study was to retrospectively analyze diving fatalities occurring in Primorje-Gorski Kotar County (northern Croatian littoral), Croatia between 1980 and 2010 in order to identify differences between fatally injured tourist and resident divers, as well as temporal changes in the frequency of diver deaths. METHODS: Medico-legal and police reports of 47 consecutive fatal diving cases were reviewed to determine the frequency of death among divers in relation to year and month of death, age, sex, nationality, organization of diving, diving type, and health condition. RESULTS: The majority of victims were foreign citizens (59.6%) most of whom fell victim to scuba diving (70.4%). It was found that 79% of resident divers succumbed during free-diving. The number of diving fatalities increased significantly in the last three decades, especially among free-divers. Of the victims, 93% were males, usually belonging to younger age groups with tourist divers being significantly older than local divers. And 31.9% of divers, mostly tourists, showed signs of acute, chronic, or congenital pathological conditions. CONCLUSION: Fatally injured foreign divers differ from resident diver fatalities in diving method and age. Tourists are the group most at risk while scuba diving according to the Croatian sample. Occupational scuba divers and free-divers are the group most at risk among resident divers. This study is an important tool in uncovering the most common victims of diving and the related risk factors. It also highlights the problems present in the legal and medical monitoring of recreational divers and discusses possible pre-event, event, and post-event preventive actions that could lead to reduced mortality rates in divers.

Diffusion tensor MRI of spinal decompression sickness.

In order to develop more sensitive imaging tools for clinical use and basic research of spinal decompression sickness (DCS), we used diffusion tensor MRI (DTI) validated by histology to assess DCS-related tissue injury in sheep spinal cords. DTI is based on the measurement of water diffusion indices, including fractional anisotropy (FA) and mean diffusion (MD) to detect tissue microstructural abnormalities. In this study, we measured FA and MD in white and gray matter spinal cord regions in samples taken from sheep following hyperbaric exposure to 60-132 fsw and 0-180 minutes of oxygen pre-breathing treatment before rapid decompression. The main finding of the study was that decompression from >60 fsw resulted in reduced FA that was associated with cell death and disrupted tissue microstructure in spinal cord white matter tracts. Additionally, animals exposed to prolonged oxygen pre-breathing prior to decompression demonstrated reduced MD in spinal cord gray matter regions regardless of dive depth. To our knowledge, this is the first study to demonstrate the utility of DTI for the investigation of DCS-related injury and to define DTI biomarkers of spinal DCS.

Interrupted oxygen pre-breathing and decompression outcomes in swine.

BACKGROUND: Rescue from a disabled submarine may result in substantial risk for severe decompression sickness (DCS) among survivors. Oxygen prebreathe (OPB) before rapid decompression has been shown to significantly reduce risk or delay onset for severe DCS in animals. However, the duration of this benefit remains unknown and might even be lost if a delay between the prebreathe period to initiation of recompression therapy allows for nitrogen reaccumulation. METHODS: We hypothesized that the benefit of OPB would be lost following subsequent periods of air interruption in a 70-kg swine saturation model. Following OPB of 45 or 60 min with varying periods (30, 45, 60 min) of air interruption, 61 swine exposed to 2.7 ATA for 22 h were rapidly decompressed. Swine without OPB served as negative controls and swine treated with 45 min of OPB without air interruption served as positive controls. RESULTS: Comparing experimental groups for Type II DCS incidence showed OPB120/60 being the only experimental group (11%) statistically different than the negative control group OPB0 (80%). Log rank tests comparing Type II DCS free survival only showed statistically significant differences for OPB45/60 compared to positive control group OPB45, while, more importantly, demonstrating a significant difference for OPB120/60 compared to that approximated for OPB45, indicating a significant reversal of the air interruption effects with longer OPB on Type II DCS disease free survival. DISCUSSION: Based on these findings we concluded that the protective effects of OPB against severe DCS are reduced with increasing periods of air interruption.

The emulsified perfluorocarbon Oxycyte improves spinal cord injury in a swine model of decompression sickness.

STUDY DESIGN: A prospective, animal model for pharmacological intervention of decompression sickness (DCS), including spinal cord (SC) injury. BACKGROUND: Signs and symptoms of DCS can include joint pain, skin discoloration, cardiopulmonary congestion and SC injury; severity ranges from trivial to fatal. Non-recompressive therapy for DCS may improve time-to-treatment and therefore impact mortality and morbidity. OBJECTIVES: Oxycyte at 5 cc kg(-1) provides both SC protection and statistically significant survival benefit in a swine model of DCS. The purpose of this study was to test whether a reduced dose of Oxycyte (3 cc kg(-1)) would provide similar benefit. SETTING: Silver Spring, MD, USA METHODS: Male Yorkshire swine (N=50) underwent a non-linear compression profile to 200 fsw (feet of sea water), which was identical to previous work using the 5 cc kg(-1) dose of Oxycyte. After 31 min of bottom time, decompression was initiated at 30 fsw per minute until surface pressure was reached. Following decompression and the onset of DCS, intravenous Oxycyte or saline was administered with concurrent 100% O(2) for 1 h. The primary end point was DCS-induced mortality, with Tarlov score and SC histopathology as secondary end points. RESULTS: Oxycyte administration of 3 cc kg(-1) following surfacing produced no significant detectable survival benefit. Animals that received Oxycyte, however, had reduced SC lesion area. CONCLUSION: Further studies to determine the lowest fully efficacious dose of Oxycyte for the adjunct treatment of DCS are warranted.

Decompression illness: clinical aspects of 5278 consecutive cases treated in a single hyperbaric unit.

BACKGROUND: Decompression illness (DCI) is a major concern in pressure-related activities. Due to its specific prerequisite conditions, DCI is rare in comparison with other illnesses and most physicians are inexperienced in treatment. In a fishery area in northern China, during the past decade, tens of thousands of divers engaged in seafood harvesting and thousands suffered from DCI. We established a hyperbaric facility there and treated the majority of the cases. METHODS AND RESULTS: A total of 5,278 DCI cases were admitted in our facility from February 2000 through December 2010 and treated using our recompression schedules. Cutaneous abnormalities, joint and muscular pain and neurological manifestations were three most common symptoms. The initial symptom occurred within 6 h after surfacing in 98.9% of cases, with an overall median latency of 62 min. The shorter the latent time, the more serious the symptoms would be (P<0.0001). Nine cases died before recompression and 5,269 were treated using four recompression schedules, with an overall effectiveness rate of 99.3%. The full recovery rate decreased with the increase of the delay from the onset of symptoms to the treatment (P<0.0001). CONCLUSIONS: DCI presents specific occurrence rules. Recompression should be administered as soon as possible and should never be abandoned irrespective of the delay. The recompression schedules used were effective and flexible for variety conditions of DCI.

Per-capita claims rates for decompression sickness among insured Divers Alert Network members.

Decompression sickness (DCS) in recreational diving is a rare and usually self-limiting injury, but permanent disability can occur. Incidence rate estimates are difficult to establish because the number of divers at risk is usually unknown in population samples with well-documented DCS. We estimated the annual per-capita DCS incidence rates for 2000-2007 based on insurance claims submitted by members of the Divers Alert Network (DAN), Durham, N.C., with dive accident insurance. The overall per-capita DCS claims rate (DCR) was 20.5 per 10,000 member-years. Based on the age-adjusted DCR, males submitted 28% more claims than females. Male-to-female difference was greatest between 35 and 40 years of age and disappeared by the mid-50s. Highest rates were observed in the 30- to 39-year age category, after which DCR declined with increasing age. Highest yearly DCR was estimated in 2002. Insurance dropout rate was greater among those who had DCS in the first year of their insurance compared to those who did not have DCS in their first year.