Three-year incidence of low back pain in an initially asymptomatic cohort: clinical and imaging risk factors.
METHODS
Prospective cohort study of randomly selected Veterans Affairs out-patients without baseline low back pain (LBP).


OBJECTIVE
To determine predictors of new LBP as well as the 3-year incidence of magnetic resonance imaging (MRI) findings.


BACKGROUND
Few prospective studies have examined clinical and anatomic risk factors for the development of LBP, or the incidence of new imaging findings and their relationship to back pain onset.


METHODS
We randomly selected 148 Veterans Affairs out-patients (aged 35 to 70) without LBP in the past 4 months. We compared baseline and 3-year lumbar spine MRI. Using data collected every 4 months, we developed a prediction model of back pain-free survival.


RESULTS
After 3 years, 131 subjects were contacted, and 123 had repeat MRI. The 3-year incidence of pain was 67% (88 of 131). Depression had the largest hazard ratio (2.3, 95% CI = 1.2-4.4) of any baseline predictor of inci-dent back pain. Among baseline imaging findings, central spinal stenosis and nerve root contact had the highest, though nonsignificant, hazard ratios. We did not find an association between new LBP and type 1 endplate changes, disc degeneration, annular tears, or facet degeneration. The incidence of new MRI findings was low, with the most common new finding being disc signal loss in 11 (9%) subjects. All five subjects with new disc extrusions and all four subjects with new nerve root impingement had new pain.


CONCLUSIONS
Depression is an important predictor of new LBP, with MRI findings likely less important. New imaging findings have a low incidence; disc extrusions and nerve root contact may be the most important of these findings.
Department of Radiology, University of Washington, Seattle, Washington 98195, USA. jarvikj@u.washington.edu
Jeffrey G
JG
Jarvik
William
W
Hollingworth
Patrick J
PJ
Heagerty
David R
DR
Haynor
Edward J
EJ
Boyko
Richard A
RA
Deyo
D000328:Adult; D000368:Aged; D003863:Depression / Q000453:epidemiology; D004185:Disability Evaluation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007405:Intervertebral Disc Displacement / Q000453:epidemiology / Q000473:pathology; D017116:Low Back Pain / Q000453:epidemiology* / Q000473:pathology*; D008159:Lumbar Vertebrae / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010045:Outpatients / Q000706:statistics & numerical data; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D011446:Prospective Studies; D011843:Radiculopathy / Q000453:epidemiology / Q000473:pathology; D012307:Risk Factors; D013130:Spinal Stenosis / Q000453:epidemiology / Q000473:pathology; D014728:Veterans / Q000706:statistics & numerical data