Body of water involved in older adult drowning deaths in the United States.

Abstract

To the Editor: Despite the lower mortality from drowning in U.S. older adults (1.5 deaths per 100,000 population) than in other countries,1 many of these drowning deaths can be prevented.2 Design of preventive measures depends on the body of water (e.g., bathtub, swimming pool, natural water) involved in the drowning. The current study was thus designed to examine the bodies of water involved in older U.S. adult drowning deaths according to sex and season to provide epidemiological information for injury prevention programs. Mortality Multiple Cause Files were used to identify unintentional drowning deaths in the United States between 2006 and 2010 using International Classification of Diseases, Tenth Revision (ICD-10) codes W65 to W743 (W65 and W66, bathtub; W67 and W68, swimming pool; W69 and W70, natural water (e.g., lake, stream, ocean), W73 and W74, all others). The months were grouped into four seasons: winter (December, January, February), spring (March, April, May), summer (June, July, August), and fall (September, October, November). Mortality (deaths per 100,000 population) and proportion of each type of body of water involved were then presented according to sex and season. Older men had a drowning rate three times as high as that of older women (21.7 vs 7.2). The most common body of water involved in drowning death was natural water for older men (43% of deaths) and was highest in summer (45%) and lowest in winter (37%) (Table 1). The second most common body of water involved was swimming pool, which was also highest in summer (24%) and lowest in winter (15%). For older women, one-fourth of drowning deaths involved natural water. The most common body of water involved for older women was bathtub, which accounted for 39% of drowning deaths. The proportion involving bathtub was highest in winter (52%). The findings of this study indicate that older men had a drowning rate three times as high as that of older women. The most common body of water involved in older U.S. adult drowning deaths was natural water for men and bathtub for women, especially in winter. The proportion involving natural water decreased with age, and the percentage involving bathtub increased with age in both sexes. These results indicate that older men are probably more involved in hazardous activities with natural water (e.g., boating, fishing, swimming) than women of the same age. Alcohol may be involved as a factor leading to unintentional drowning. Previous study has indicated that many drowning deaths due to falling into water are boating related and involve the use of alcohol.4 Many studies have suggested that bathtubs are common sites for drowning deaths in older adults.5-8 One possible explanation is that older adults have higher risks of falling into bathtubs,5 yet the current findings show that only one-tenth (60/588) of older U.S. adult bathtub drowning deaths were coded as ICD-10 code W66, “drowning and submersion following fall into bathtub.” The majority of deaths were coded as W65, “drowning and submersion while in bathtub.” Another explanation is that older adults have higher incidences of acute attacks of medical conditions such as heart attack, stroke, hypoglycemic shock, and seizure, resulting in drowning while in a bathtub or falling into and drowning in a bathtub.9 Several limitations should be noted in interpreting the findings of this study. First, the reporting rate for unspecified body of water may differ between medical examiners and coroners, although it is unlikely that this misclassification differs according to sex and season. Second, detailed information on which kind of natural water (e.g., river, lake, sea), activity (e.g., swimming, boating, fishing), and circumstances (e.g., under the influence of alcohol, after seizure or heart attack) were involved was unavailable. Third, although not frequent, the drowning event and the death might not have occurred in the same month, affecting the seasonal rate. In conclusion, this nationwide population-based study indicated that the most common body of water involved in drowning deaths of older U.S. adults differed according to sex and season. Drowning prevention programs should be designed accordingly. The findings of this study further suggest that older adults with medical or psychiatric conditions living alone should take precautions while using bathtubs, especially in winter. Another person monitoring from outside the bathroom may help reduce risk of drowning during bathing due to an acute attack of a medical condition. Conflict of Interest: The editor in chief has reviewed the conflict of interest checklist provided by the authors and has determined that the authors have no financial or any other kind of personal conflicts with this paper. Author Contributions: Wu, Lu: study concept and design, acquisition of subjects and data, data analysis. Wu, Lu, Cheng, Kawachi: interpretation of findings, critical review of manuscript. Sponsor's Role: None.