A configural model of expert judgement as a preliminary epidemiological study of injury problems: An application to drowning
- Authors: Morgan, Damian , Ozanne-Smith, Joan
- Date: 2019
- Type: Text , Journal article
- Relation: PLoS ONE Vol. 14, no. 10 (2019), p.
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- Description: Robust epidemiological studies identifying determinants of negative health outcomes require significant research effort. Expert judgement is proposed as an efficient alternative or preliminary research design for risk factor identification associated with unintentional injury. This proposition was tested in a multi-factorial balanced experimental design using specialist judges (N = 18), lifeguards and surfers, to assess the risk contribution to drowning for swimming ability, surf bathing experience, and wave height. All factors provided unique contributions to drowning risk (p < .001). An interaction (p = .02) indicated that occasional surf bathers face a proportionally increased risk of drowning at increased wave heights relative to experienced surf bathers. Although findings were limited by strict criteria, and no gold standard comparison data were available, the study provides new evidence on causal risk factors for a drowning scenario. Countermeasures based on these factors are proposed. Further application of the method may assist in developing new interventions to reduce unintentional injury. © 2019 Morgan, Ozanne-Smith. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Descriptive epidemiology of drowning deaths in a surf beach swimmer and surfer population
- Authors: Morgan, Damian , Ozanne-Smith, Joan , Triggs, Thomas
- Date: 2008
- Type: Text , Journal article
- Relation: Injury Prevention Vol. 14, no. 1 (2008), p.62-65.
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- Description: Retrospective data extraction from two complementary mortality datasets determined the descriptive epidemiology and population rates in unintentional drowning deaths at surf beaches (n = 129). The annual average crude surf beach drowning rate was 0.28 per 100 000 population for males and 2.36 per 100 000 population for international tourists. The study generated hypotheses for risk assessment to assist intervention: adult males, international tourists, people with cardiovascular conditions, and exposure to rip currents.
Development and trial of a water exposure measure of estimated drowning risk for surf bathers
- Authors: Morgan, Damian , Ozanne-Smith, Joan
- Date: 2013
- Type: Text , Journal article
- Relation: International Journal of Aquatic Research and Education Vol. 7, no. 2 (2013 2013), p. 116-135
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- Description: To better address drowning issues, risk assessment at the group and sample levels would be enhanced by precise measures of exposure to water. The aim of the study was to develop and pilot test a method of measuring exposure to water based on estimating immersions for surf bathers. Validated direct observation counts provided peak-bathing period point estimates and a daily bather immersion profile for an identified sampling frame comprising 20 beaches over 39 summer days. An estimated 10,089 water immersions occurred at the peak-bathing period in the sampling frame. Swimmers comprised 86.0% and surfers with equipment 14.0% of the observed bathing sample, respectively. For swimmers only on patrolled beaches, 77.1% bathed in the lifesaver supervised (flag) zones. The study has implications for the provision of organized bather supervision and provides a foundation for generation of hypotheses on the nature of drowning risk for selected surf bather groups.
Direct observation measurement of drowning risk exposure for surf beach bathers
- Authors: Morgan, Damian , Ozanne-Smith, Joan , Triggs, Thomas
- Date: 2009
- Type: Text , Journal article
- Relation: Journal of Science and Medicine in Sport Vol. 12, no. 72 (2009), p. 457-462
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- Description: Because not all persons bathe at surf beaches, drowning rates based on resident population are likely to be underreported. To facilitate more precise drowning risk exposure data, this study aimed to develop a reliable direct observation measure of frequency and duration for surf beach bather exposure to water, by gender and age group. Bathers were defined as persons entering the water to wade, swim or surf with equipment. Observed bathers were systematically selected entering the water in daylight hours at six patrolled or unpatrolled beaches over 10 days. Variables measured were: weather and water conditions, water entries, duration of water exposure, water exposure location and person factors. The dataset comprised 204 (69.6%) males and 89 (30.4%) females, with males more likely to be in an older age group (p < 0.05). Compared to females, males spent longer in the water, were more likely to use surfing equipment, and mainly used a surf zone located farther from the shore in deeper water (p < 0.05). Two factors were significant predictors of bathing duration (adjusted R2 = 0.45): main surf zone occupied (based on water depth and distance from shore); and surf equipment used. The study provides new information about water exposure for bathers at surf beaches and new methods for measuring exposure to drowning risk. The findings suggest that overrepresentation of adolescent and adult males in surf beach drowning statistics is in part a product of greater total exposure to the water plus more frequent exposure to deeper water and bathing farther from shore.
Identification of observed factors that predict bather water-immersions at beaches
- Authors: Morgan, Damian , Ozanne-Smith, Joan
- Date: 2013
- Type: Text , Journal article
- Relation: Ocean and Coastal Management Vol. 84, no. (2013), p. 180-183
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- Description: Coastal managers require accurate and relevant visitor information to manage visitor's leisure and recreation experiences. The study reports the development of a predictive model of bather water-immersions at selected beaches in Victoria, Australia for the daily peak-bathing period. Criterion variable data were collected over two summer periods to provide external validation. Predictor variables were observed on site or from secondary data. Results showed a statistically significant model meeting the required assumptions: Adjusted R2 = 0.65: F2, 292 = 270.50, p < 0.001; R2 95% CI: 0.58 to 0.71. Significant predictor variables were daily maximum air temperature and level of service (no service, toilet/water, or kiosk/club). Further research is required to assess the model generalisability to other beach locations and time frames
Measurement of a drowning incidence rate combining direct observation of an exposed population with mortality statistics
- Authors: Morgan, Damian , Ozanne-Smith, Joan
- Date: 2015
- Type: Text , Journal article
- Relation: International Journal of Injury Control and Safety Promotion Vol. 22, no. 3 (2015), p. 209-214
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- Description: Drowning risk factors may be identified by comparing drowning incidence rates for comparable at-risk populations but precise methods are lacking. To address this knowledge gap, an ecological study extrapolated crude time-duration exposure to water for a specified at-risk sample of surf bathers to estimate the bather population for all wave-dominated beaches in Victoria, Australia, over a four-year summer season period. An incidence rate was calculated using surf bather drowning deaths frequencies matched for time and location. For the sample, 47,341 hours of surf bathing were estimated from 177,528 bathing episodes. Generalising these results to Victoria, the crude drowning deaths incidence rate in the summer season was 0.41 per 1,000,000 person-hours of surf bathing (95% CI 0.37–0.45). Further application of the method, particularly in open water settings, may be used to identify candidate drowning risk factors to advance drowning prevention strategies.
Self-reported water and drowning risk exposure at surf beaches
- Authors: Morgan, Damian , Ozanne-Smith, Joan , Triggs, Thomas
- Date: 2009
- Type: Text , Journal article
- Relation: Australian and New Zealand Journal of Public Health Vol. 33, no. 2 (2009), p. 180-188
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- Description: OBJECTIVE: To document patterns of water exposure at surf beaches by gender and identify factors that predict bather confidence to return to shore if caught in a rip current. METHOD: Recreational surf beach bathers (N=406) provided self-completed data on water exposure patterns, surf activity behaviours and potential drowning risk and protective factors. RESULTS: Relative to females, males visited surf beaches more frequently, expected to spend longer in the water and in deeper water, and more often bathed after using alcohol (p<0.05). Confidence to return to shore if caught in a rip current was predicted by confidence to identify a rip current, self-rated swimming ability, gender, times visited any beach, and age in a standard linear regression model (adjusted R(2)=0.68). CONCLUSION: The study supports explanations that high male drowning rates result from more frequent exposure to water than females at high situational risk levels. IMPLICATIONS: Controlled studies are required to determine the role in drowning of overconfidence, swimming ability, surf experience, floatation .
Surf bather drowning risk and exposure-related factors identified by an expert panel
- Authors: Morgan, Damian , Ozanne-Smith, Joan
- Date: 2012
- Type: Text , Journal article
- Relation: International Journal of Aquatic Research and Education Vol. 6, no. 4 (2012 2012), p. 336-349
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- Description: In the absence of an established literature, identifying and quantifying surf bather drowning risk factors requires a clearly defined problem-focused research strategy. To initiate this strategy, nominal group technique (NGT) was used to identify and rank risk and water exposure-related factors based on consensus of an expert panel. The results identified, in order, level of experience (encompassing swimming ability in surf conditions), lack of local knowledge (encompassing awareness of surf hazards, including rip currents), and surf conditions (encompassing prevailing wave height and rip currents) as the three most influential surf bather drowning risk factors. Factors most influential on exposure to water were identi fied and ranked as prevailing weather geographic location (encompassing bather accessibility to the beach), and infrastructure (encompassing the presence of artificial beach amenities). This study provides direction for future analytic epidemiological research and complementary studies on drowning at surf beaches and other locations. ABSTRACT FROM AUTHOR
Surf lifeguard rescues
- Authors: Morgan, Damian , Ozanne-Smith, Joan
- Date: 2013
- Type: Text , Journal article
- Relation: Wilderness & Environmental Medicine Vol. 24, no. 3 (2013), p. 285-290
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- Description: Objective This study assessed the utility of lifeguard rescue data for providing information on person and situation factors to inform surf bather drowning prevention research. Methods The dataset comprised 872 beach-days (daily lifeguard reports) obtained from 26 beaches over a 95-day period in Victoria, Australia. Results The rescue rate was 128 per 100,000 in-water bathers. One or more rescues were required on 125 beach-days (14%). Rescue on a beach-day was more likely for offshore wind conditions, relatively high daily air temperatures, and high bather numbers (P < .05). Compared to female bathers, males were more frequently rescued (65%) and more likely (P < .05) to be from a younger age group (30 years or less), although being older was associated with a relatively poorer condition on rescue. Conclusions Although rescues are proportional to water exposure, frequencies are also influenced by situation and person factors. Bathers at relatively high risk of rescue are hypothesized to be overrepresented in amenable sea and weather conditions, and poor patient condition on rescue may be associated with exposure to a preexisting health condition.