title: Assessment of the Risk of Fractures Because of Service on Diesel Submarines: A Retrospective Cohort Study.
abstract: BACKGROUND
  Submariners are known to have decreased bone mass following periods of long submersion. We examined whether this produces a higher predilection to fractures.
  
  
  METHODS
  This is a retrospective cohort study. Data were collected from the computerized medical records of 457 consecutive submariners (serving 1091.42 man-years). The control group included 3,219 consecutive sailors, (serving 5845.04 man-years). Groups were stratified according to age at induction, body mass index, place of birth, and status of service (i.e., compulsory versus professional). Analysis of fracture incidence and comparison of proportions between the groups was conducted using χ(2) tests and Fisher's exact test. The hazard ratio for fractures was performed using a survival analysis regression model for each group (Cox Proportional Hazard Model).
  
  
  RESULTS
  Nineteen submariners (4.2%) and 94 sailors (2.9%) were shown to have fractures during their service (RR = 1.42, p = 0.15). A Cox proportional hazard model was employed. No statistically significant difference was found between the 2 groups (HR = 1.037, p = 0.89). No correlation was found between length of service and risk of fracture. Most fractures suffered by submariners occurred outside their work environment.
  
  
  CONCLUSIONS
  Submariners are repeatedly exposed to prolonged submersions that are deleterious to bone strength. However, no statistically significant difference in the incidence of fractures was found between submariners and surface sailors. This is an important finding for the bone and occupational health of submariners in general.
authors.affiliation: Israeli Defense Forces Medical Corp.
authors.forename: Amit
authors.initials: A
authors.lastname: Saad
authors.affiliation: Israeli Defense Forces Medical Corp.
authors.forename: Carmel
authors.initials: C
authors.lastname: Kala
authors.affiliation: Israeli Defense Forces (IDF) Navy, Haifa Naval Base Department of Medicine, Tsim Square, Haifa, Israel; IDF Medical Corp.
authors.forename: Sharon
authors.initials: S
authors.lastname: Ohayon
authors.affiliation: Israeli Defense Forces (IDF) Navy, Haifa Naval Base Department of Medicine, Tsim Square, Haifa, Israel; IDF Medical Corp.
authors.forename: Lior
authors.initials: L
authors.lastname: Feldman
authors.affiliation: Israeli Defense Forces Medical Corp.
authors.forename: Eran
authors.initials: E
authors.lastname: Galili
authors.affiliation: Israeli Defense Forces (IDF) Navy, Israeli Naval Medicine Institute, Tsim Square, Haifa, Israel, IDF Medical Corp.
authors.forename: Yoav
authors.initials: Y
authors.lastname: Yanir
authors.affiliation: Child Health and Sports Center, Meir Medical Center, 59 Tschernikhovski Street, Kfar Sava, Israel 4428164.
authors.forename: Dan
authors.initials: D
authors.lastname: Nemet
authors.affiliation: Israeli Defense Forces (IDF) Navy, Haifa Naval Base Department of Medicine, Tsim Square, Haifa, Israel; IDF Medical Corp.
authors.forename: Itamar
authors.initials: I
authors.lastname: Netzer
mesh_terms: D000293:Adolescent; D000328:Adult; D000359:Aftercare; D005260:Female; D050723:Fractures, Bone / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D007557:Israel / Q000453:epidemiology; D008297:Male; D008887:Military Medicine / Q000379:methods*; D008889:Military Personnel; D015995:Prevalence; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D013997:Time Factors; D055815:Young Adult