In 1995, researchers sought to understand if there was a correlation between how recreational divers dive and the prevalence of decompression sickness (DCS). For nearly 10 years, data was collected on real-world open-water dive profiles and explored the observed incidence and predicted incidence of DCS.
The study was completed in 2008.
In 1995, DAN undertook a project to prospectively collect data about how recreational divers dive and how often they get decompression sickness (DCS). For the first time, the dive exposures were described in detail thanks to the availability of dive computers with recording capability. Dive profile details — depth changes over time — were collected from volunteers using commercially available dive computer/recorders. The presence or absence of a suspected decompression sickness symptoms after diving were also reported. The objectives were to collect real-world open-water dive profile data, explore how probabilistic models perform with actual recreational dive data, and correlate the observed incidence and predicted incidence of DCS.
The enrollment of volunteers began in 1995 and continued until 2008. The study was possible thanks to dive computer manufacturers who adopted a standard format for data exported from their dive computers. By the end of the study there were 11 manufacturers participating. In the beginning, due to the complexity of the procedures, DAN had trained volunteers to act as field data coordinators and to assist with field data collection. Later on, procedures became simpler, and any diver with some basic technical skill could participate on their own. By the end of the study, more than 10,000 divers participated, collecting nearly 200,000 dives. Unfortunately, not all records were usable because they either did not fit our definition of a dive (deeper than 10 feet and longer than three minutes), there were recording errors or incomplete reporting of outcomes. After thoroughly cleaning and verifying the data, we retained 122,129 dives for the final analysis. In only 38 of these dives was the outcome classified as DCS. The overall incidence of DCS was 3.4 per 10,000 dives, but it varied significantly among different groups of divers. The lowest incidence was among basic recreational divers (7 per 10,000), and higher incidences were found among dive guides in Cozumel and cold-water wreck divers in Scapa Flow. The small number of DCS cases limited the analysis, which is detailed in the paper in the Undersea Hyperbaric Medicine Journal. The abstract is below.
We learned many lessons from this crowd-sourced study, and these will be useful in similar studies in the future. Besides technical issues, the major problem was the reporting of additional data not recorded by dive computers, including prompt post-dive health status reports. With advances in dive computer technology, widespread use of mobile devices and the popularity of crowdsourcing, another study of dive exposure and outcomes is probably already taking shape in the minds of enthusiastic researchers.
Additional Reading and References
- Richard G. Dunford MS, Petar D. Denoble MD, Robert Forbes BA, Carl F. Pieper DrPh, Laurens E. Howle PhD, Richard D. Vann PhD. A study of decompression sickness using recorded depth-time profiles. Undersea Hyperb Med 2020, 47 (1): 83-98.