Incidence and trends of low back pain hospitalisation during military service - An analysis of 387,070 Finnish young males

Background: There is evidence that low back pain (LBP) during young adulthood and military service predicts LBP later in life. The purpose of this study was to investigate the incidence and trends of LBP hospitalisation among Finnish military conscripts. Methods: All male conscripts performing their compulsory military service during 1990-2002 were included in the study population. Altogether 387,070 military conscripts were followed throughout their six-to-twelve-month service period. Data on LBP hospitalisations were obtained from the National Hospital Discharge Register. Results: Altogether 7,240 LBP hospitalisations were identified among 5,061 (1.3%) male conscripts during the study period. The event-based incidence of LBP hospitalisation was 27.0 (95% confidence interval (CI): 25.7-28.2). In most cases, the diagnosis was unspecified LBP (n = 5,141, 71%) followed by lumbar disc disorders (n = 2,069, 29%). Hospitalisation incidence due to unspecified LBP was 19.1 per 1,000 person-years (95% CI: 18.3 to 20.4), and 7.8 per 1,000 person-years ( 95% CI: 6.7 to 8.3) due to lumbar disc disorders. The incidence of unspecified LBP remained unaltered, while hospitalisation due to lumbar disc disorders declined from 1993 onwards. Conclusion: Although conscripts accepted into military training pass physician-performed examinations as healthy, young adults, LBP hospitalisation causes significant morbidity during military service.