Studying the Health and Performance of Shipboard Sailors: An Evidence Map

Health Conditions Among Navy Submariners at the End of Active Duty; A Retrospective Cohort Study

INTRODUCTION

Maintaining healthy, well-trained, and highly qualified armed forces is critical for ensuring military readiness. The purpose of this article is to contribute to the body of research focused on the health of U.S. Navy submariners and to identify the health conditions of U.S. Navy submariners during their final year of active duty service.

MATERIALS AND METHODS

In this retrospective cohort study, we examined medical records and personnel files of separating U.S. Navy sailors who were: (1) active duty between 2009 and 2018; (2) separated before 2019; and (3) were assigned to a submarine for at least 30 days. Both officers and enlisted service members were included. We linked, described, and analyzed data from the Defense Health Agency, Military Health System Data Repository (MDR), and the Bureau of Naval Personnel (BUPERS). International Classification of Diseases (ICD) diagnoses codes were obtained from MDR. Data collected from BUPERS include age, sex, and rank. We determined the number of individuals who had at least one diagnosed condition (identified as a three-digit ICD code). We report the number of diagnoses and calculate prevalence rates and confidence intervals per condition, as well as prevalence rates per year, using standard formulas. The study was approved by the Naval Submarine Medical Research Laboratory Institutional Review Board.

RESULTS

During the study period, 26,014 submariners separated from the Navy. The average number of separations per year was 2,601. About a third of the separating submariners were in the 25 to 29 age group and over 50% were under 30 years of age. Of the three-digit individual ICD codes, some of the highest operationally relevant rates over the 10-year study period (2009-2018) were for joint disorders (prevalence rate [PR] = 180 per 1,000 submariners), back disorders (PR = 128), and sleep disorders (PR = 134). Three mental-health-related conditions were also among the 20 conditions with the highest rates.

CONCLUSIONS

High rates of specific diagnoses such as joint disorders indicate the need for additional study to examine causal relationships, to determine which conditions may contribute to lost work time, early separations, or low rates of reenlistment and which conditions might be a result of specific military occupations or duties. Study strengths are the large number of subjects and the long period of observations. A study weakness was the inability to identify submariners who separated because of health conditions. The overall impact of the study is that it identifies urgent health risks and establishes a way to prioritize future research. Future research should include a focus on medically separated personnel; compare rates for submariners to other military groups including all-Navy and all-Department of Defense; and determine specific and relative risks as a necessary precursor to developing, implementing, and testing risk reduction and health improvement interventions.

The Development, Implementation, and Feasibility of a Circadian, Light, and Sleep Skills Program for Shipboard Military Personnel (CLASS-SM)

Service members face unique barriers to sufficient and high quality sleep. In the present study, a circadian, light, and sleep skills program for shipboard military personnel (CLASS-SM) was designed to encourage and inform strategies that support optimal sleep and circadian health in the context of those barriers. Phase 1 included program development and refinement via an iterative formative evaluation, including structured interviews with service members and feedback from veterans and experts, resulting in further tailoring to the population. In Phase 2, the highly tailored program was administered to shipboard personnel (n = 55), and acceptability indicators were measured. Sleep- and circadian-related knowledge (pre- and post-program) and the perceived relevance of, and satisfaction with, program content (post-program) were assessed. Before the intervention, most individuals were unaware that 7−9 h of sleep is recommended (72%) and had little understanding of the physiological effects of light; however, knowledge scores increased significantly post-program, from 51% to 88% correct (p < 0.0001). Reception was positive, with high reported satisfaction and relevance. Most individuals reported that they learned something new (89%), planned to use one or more learned strategies (100%), and intended to share learned information with others (85%); the physiological effects of light and circadian rhythms were the content areas most frequently reported as new and useful. The results demonstrate the need for, and feasibility of, the delivery of this program in operational environments.