Diagnoses of low back pain, active component,
U.S. Armed Forces, 2010-2014

A Comparative Effectiveness Clinical Trial

This section is compiled by Frank M. Painter, D.C.
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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. [4]

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.


Table 1

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).

Figure 1

Table 2

Table 3

Table 4

“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. [10]

U.S. military members in combat set­tings carry heavier loads than those who served in such settings in the past. [11] 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. [12]

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. [13]

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. [14]

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. [15] 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.


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