Medical Surveillance Monthly Report (MSMR) 2015 (Dec); 22 (12): 8–11 ~ FULL TEXT
Leslie L. Clark, PhD, MS; Zheng Hu, MS
Low back pain (LBP) is a common cause of disability, lost worker productivity, and healthcare costs in both military and civilian populations. During the 5-year surveillance period of this analysis, the LBP diagnoses of interest were associated with more than 6 million outpatient healthcare encounters and more than 25,000 hospitalizations among active component service members. Annual numbers of outpatient encounters for LBP diagnoses increased 34% during 2010-2014. Annual numbers of inpatient encounters decreased during the period. Incidence rates were lowest among the youngest service members and increased with advancing age. Of all service members ever given a LBP diagnosis during the surveillance period, 91% were diagnosed at least once with a condition in the broad category "nonspecific back pain." The most common specific diagnosis during the surveillance period was lumbago. The discussion covers the importance of LBP in the military, initiatives to lower the incidence of, and enhance the care of, LBP, and methodologic limitations to the analysis.
From the FULL TEXT Article:
Low back pain (LBP) is a highly prevalent condition worldwide and a leading cause of disability that imposes a significant economic burden in terms of both lost worker productivity and healthcare costs. In the U.S., LBP is one of the most common reasons for which adults seek medical care. In 2012, low back symptoms were the 10th most frequent reason for physician office visits in the U.S. population, resulting in more than 13 million physician office visits. [1-3]
Among active component military members, LBP is also one of the most frequent reasons for seeking medical care. In the annual MSMR burden of disease issue published each April, “other back problems,” has been the category responsible for the most medical encounters every year since 2011. In 2015, this category (which includes diagnoses such as lumbago and unspecified backache) was the primary diagnosis in more than a million medical encounters, affecting 223,094 service members. 
LBP can also have a significant negative impact on military operations. It is one of the leading causes of evacuations from combat theaters of operations and one of the most frequent reasons for seeking medical care in combat theaters. [5-7]
In 2010, the MSMR estimated the incidence of LBP diagnosed during medical encounters using an algorithm developed by Cherkin et al. that utilizes ICD-9 diagnostic and procedure codes to identify patients with “mechanical low back pain.” Mechanical LBP was defined as local or radicular pain associated with conditions of the sacrum or lumbar spine unrelated to major trauma, neoplasms, pregnancy, or infectious or inflammatory causes (and subsequently referred to as low back pain). [8, 9] This report updates these estimates through 2014 by using the same algorithm.
The surveillance period was 1 January 2010 through 31 December 2014. The surveillance population included all active component service members who served at any time during the surveillance period.
Diagnoses of LBP were defined by inpatient or outpatient medical encounters that were documented with a diagnosis (in any diagnostic position) of any of 66 ICD-9 codes indicative of low back problems. The 66 specific diagnoses were grouped into seven clinical categories for summary purposes (nonspecific back pain, miscellaneous back problems, degenerative changes, herniated disc, possible instability, spinal stenosis, and sequelae of back surgery). Encounters that were associated with major trauma (e.g., traffic accidents, vertebral fractures or dislocations), pregnancy, neoplasms, infections, or other inflammatory causes of back pain were excluded.
Incident diagnoses of LBP were defined by the individual’s first occurring qualifying LBP-related medical encounter during the surveillance period. Incidence rates of LBP overall were calculated by dividing the total of first (incident) episodes of LBP during the period by the total years (person-time) of active military service during the same period. Also, incidence rates of each of seven clinical categories of LBP were calculated separately. For these analyses, individuals could be counted as incident cases once in each category during the 5-year surveillance period. Medical encounters with multiple LBP indicator diagnoses were classified by using the LBP diagnosis that was reported in the highest diagnostic position of the health record. In this analysis, incidence is defined as the first encounter during the surveillance period. Prevalent cases of back pain (i.e., individuals who had been diagnosed prior to 2010) were not excluded from this analysis.
During the 5-year surveillance period, active component members had 6,268,752 outpatient medical encounters and 25,930 inpatient encounters that included an ICD-9 code for one of the LBP diagnoses of interest (Table 1). Among incident outpatient encounters, about 72% (n=492,609) of the LBP diagnoses were in the primary diagnostic position, while approximately 13% of the LBP diagnoses were in the primary diagnostic position in incident inpatient encounters (data not shown).
Slightly less than two-thirds of ambulatory visits (n=3,930,536; 62.7%) were classified as “nonspecific back pain,” and approximately one-fifth of all LBP-related ambulatory visits were categorized as “miscellaneous back problems” (n=1,288,934; 20.6%). “Degenerative changes” represented about 9% of outpatient diagnoses (n=563,293), while the category of “herniated disc” comprised approximately 6% of all outpatient diagnoses (n=359,810); the remaining clinical categories combined accounted for only 2% of all visits. About 40% of hospitalizations with a LBP diagnosis were documented with “nonspecific back pain” (n=10,663, 41.1%) related diagnoses (Table 1).
“Lumbago” was by far the most frequent diagnosis (at the three-digit level of the ICD-9) during ambulatory visits for LBP. During the 5-year period, 519,740 service members had 3,216,360 ambulatory visits for lumbago (average per person: 6.2) (Figure 1). The diagnoses of “backache, unspecified” (468,012 visits; 193,193 individuals; average per person: 2.4) and “nonallopathic lesions, lumbar region” (413,025 visits; 83,421 individuals; average per person: 5.0) were the second and third most frequent diagnoses reported during LBP-related visits. (Figure 1).
During the 5-year period, 689,073 service members had at least one incident LBP-related medical encounter. The overall incidence rate was 120.0 visits per 1,000 person-years (p-yrs) (Table 2). The number of service members with at least one incident LBP-related visit during each calendar year sharply declined from 2010 (n=214,337) to 2014 (n=99,202). (Table 3) Although LBP-related incident encounters decreased over the time period, the overall number of LBP-related ambulatory encounters increased 34% over the time period (2010: 1,004,820; 2014: 1,349,941), while inpatient encounters with a LBP diagnosis decreased during the period (2010: 5,106; 2014: 4,521) (Table 4).
Among the categories of LBP, the highest incidence rates during the surveillance period were for “nonspecific back pain” (Table 2). Of service members with any LBP diagnoses during the period, 91% were diagnosed at least once with “nonspecific back pain” (rate: 106.0 per 1,000 p-yrs), while more than one-third (37%) were diagnosed with “miscellaneous back problems” (rate: 37.7 per 1,000 p-yrs). About 17% were diagnosed with “degenerative changes” (rate: 17.0 per 1,000 p-yrs), and 12% with “herniated disc” (rate: 11.6 per 1,000 p-yrs) (Table 2).
For all categories of LBP, incidence rates were lowest among the youngest service members and increased with age (Table 2). Females had higher overall crude incidence rates of LBP overall, as well as higher rates for the specific categories of “nonspecific back pain,” “miscellaneous back problems,” and “possible instability.” Incidence rates for the category of “degenerative changes” were roughly equivalent for males and females, while the categories of “herniated disc,” “spinal stenosis,” and “sequelae of back surgery” were marginally higher in males (Table 2).
During the past 5 years, nearly 700,000 active component members had at least one LBP-related medical encounter; the majority of medical encounters with LBP diagnoses were documented with nonspecific back pain diagnoses, particularly “lumbago.” This summary included medical encounters reported from fixed medical facilities outside of combat theaters; however, it has been previously documented that LBP is a significant cause of morbidity during deployment. [5-7] It has also been demonstrated that diagnoses for back conditions, along with other musculoskeletal disorders, increase in prevalence with increasing number of deployments. 
U.S. military members in combat settings carry heavier loads than those who served in such settings in the past.  A survey of U.S. soldiers in Iraq revealed a substantial increase in self-reported back and neck pain during deployment; many respondents attributed the symptoms to lengthy periods of wearing body armor; a study evaluating predictors of LBP during deployment found that length of time wearing body armor was a consistent predictor of LBP. 
Because of the high cost to the military (both in terms of direct health care costs and military operational costs) of LBP, research initiatives to develop effective strategies to prevent LBP have been the focus of several recently completed studies. One study, the Prevention of Low Back Pain in the Military cluster randomized trial, reported that brief psychosocial education, rather than traditional or specialized core stabilization exercise programs, reduced the incidence of healthcare utilization for LBP. 
Another recent study performed in new LBP patients in the Military Health System indicated that patients who received physical therapy within 2 weeks of the initial visit for back pain and who adhered to clinical practice guidelines had 60% lower total LBP-related medical costs compared to comparison groups receiving delayed or nonadherent physical therapy. 
There are several limitations of this analysis that should be considered. To allow for comparison with the previous MSMR analysis, the methods remained unchanged from the prior analysis. However, the algorithm used to identify and categorize LBP was developed in 1992; recently, Sinnott et al. published a comprehensive review of methods for identifying back and neck pain in administrative data partly to evaluate if an update of the methodology used by Cherkin et al. was warranted.  Although this analysis reported that the Cherkin algorithm had considerable overlap with more recently developed algorithms to identify back pain, the authors recommended several updates to the methodology that would likely result in the capture of more cases of LBP when applied to administrative data such as that used in this analysis. On the other hand, the methodology used in the current analysis does not require that the ICD-9 code of interest be in the primary diagnostic position. Therefore, the primary reason for seeking medical care may not have been related to LBP.
In addition, this analysis reported that incident diagnoses declined during the surveillance period; it is likely that, to some extent, this is an artifact of not excluding prevalent cases of LBP prior to the beginning of the surveillance period.
The majority of individuals who present for care for LBP pain experience a recurrent LBP episode. This analysis did not examine the rate of recurrent LBP episodes in active component service members. An extensive analysis of recurrent LBP episodes will be presented in a future issue of the MSMR.
Global Burden of Disease Study 2013 Collaborators. Global, regional, and national incidence,
prevalence, and years lived with disability for 301 acute and chronic diseases and
injuries in 188 countries, 1990–2013: a systematic analysis for the Global Burden
of Disease Study 2013. Lancet. 2015;386(9995):743–800.
Summary tables from the 2012 National Ambulatory Medical Care Survey.
Hoy D, Brooks P, Blyth F, Buchbinder R.
The epidemiology of low back pain.
Best Pract Res Clin Rheumatol. 2010;24:769–781.
Armed Forces Health Surveillance Center.
Absolute and relative morbidity burdens attributable to various illnesses and injuries,
U.S. Armed Forces, 2014.
Cohen SP, Nguyen C, Kapoor SG, et al.
Back pain during war: an analysis of factors affecting outcome.
Arch Intern Med. 2009;169(20):1916–1923.
Daniele DO, Clark LL.
Morbidity burdens attributable to various illnesses and injuries in deployed
(per Theater Medical Data Store [TMDS]) Active and Reserve Component
Service Members, U.S. Armed Forces, 2008–2014.
Armed Forces Health Surveillance Center.
Medical evacuations from Afghanistan during Operation Enduring Freedom,
Active and Reserve Components, U.S. Armed Forces, 7 October 2001–31 December 2012.
Cherkin D, Deyo R, Volinn E, et al.
Use of the International Classification of Diseases (ICD-9-CM) to identify
hospitalizations for mechanical low back problems in administrative databases.
Armed Forces Health Surveillance Center.
Low back pain, active component, U.S. Armed Forces, 2000–2009.
Armed Forces Health Surveillance Center.
Associations between repeated deployments to OEF/OIF/OND, October 2001–
December 2010, and post-deployment illnesses and injuries, active component,
U.S. Armed Forces.
Knapik JJ, Reynolds KL, Harman E.
Soldier load carriage: historical, physiological, biomechanical, and medical aspects.
Mil Med. 2004;169(1):45–56.
Roy TC, Lopez HP.
A comparison of deployed occupational tasks performed by different types of
military battalions and resulting low back pain.
Mil Med. 2013;178(8):e937–e943.
Childs JD, Wu SS, Teyhan DS, Robinson ME, George SZ.
Prevention of low back pain in the military cluster randomized trial: effects of
brief psychosocial education on total and low back pain-related health care costs.
Spine J. 2014;14(4):571–583.
Childs JD, Fritz JM, Wu SS, et al.
Implications of early and guideline adherent physical therapy for low back pain
on utilization and costs.
BMC Health Serv Res. 2015;15:150.
Sinnott PL, Siroka AM, Shane AC, Trafton JA, Wagner TH.
Identifying neck and pain in administrative data.
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