This was a prospective study of patients (study group) with symptomatic disc herniations and asymptomatic volunteers (control group) matched for age, sex, and work-related risk factors.
To determine the prevalence of disc herniation
in a matched group of asymptomatic volunteers and to access the diagnostic accuracy
of magnetic resonance imaging
, work perception
, and psychosocial factors
in identifying symptomatic disc herniations.
Summary of Background Data
Disc herniations have been reported to occur in 20–36% of asymptomatic volunteers. A valid comparison of asymptomatic individuals and patients with disc herniations has not been performed.
Forty-six patients with low back pain and sciatica severe enough to require a disceclomy were compared with 46 age-, sex-, and risk factor-matched (heavy lifting, twisting and bending, vibration, and sedentary activity) asymptomatic voluteers. Both groups had a complete clinical and magnetic resonance imaging
examination and completed a questionnaire to assess differences in the psychosocial and work perception
profiles. The prevalence and the severity of morphologic alterations (disc herniation
, disc degeneration, and neural compromise) was analyzed by two independent radiologists in a blinded fashion. Differences between both groups regarding MRI findings, work perception
(occupational mental stress, intensity of concentration, job satisfaction, and job-related resignation) and psychosocial factors
(anxiety, depression, self-control, social support, and marital status) were compared using multivariate techniques. Stepwise discriminate analysis was used to identify the best discriminating variables within the magnetic resonance image, work perception
, and psychosocial categories in terms of the diagnostic accuracy
to predict group membership (study [pain] or control [no pain] group).
Matched controls had significantly more risk factors than a group of normal individuals. The present study has presented evidence that an age-, gender-, and occupational risk factors-matched group of asymptomatic patients shows a high incidence rate of disc herniations (76%). Although significantly less than the symptomatic group incidence of 96%, this represents a much higher prevalence rate than generally expected and reported in other studies of unmatched asymptomatic volunteers. Patients had more severe disc herniations (disc extrusions) than asymptomatic volunteers (35% vs. 13%). There was no significant differences regarding disc degeneration between both groups (96% vs. 85%). The only substantial morphologic difference between both groups was the presence of a neural compromise (83% vs. 22%), which was highly significant (P
< 0.0001). There were significant differences between both groups regarding work perception
(occupational mental stress, intensity of concentration, job satisfaction, and resignation; P
<0.027) and psychosocial factors
(anxiety, depression, self-control, marital status; P
<0.0001). The best single predictor of a group membership was the extent of neural compromise. A combination of this factor with occupational mental stress, depression, and marital status was the best predictive model. With this model, the false-negative rate (potential overtreatment of disc morphology) was reduced by more than half compared with morphologic factors (nerve root compression) alone (22% vs. 11%).
In an age-, sex-, and risk factormatched group of asymptomatic individuals, disc herniation
had a substatially higher prevalence (76%) than previously reported in an unmatched group. Individuals with minor disc herniations (i.e.
, protrusion, contained discs) are at a very high risk that their magnetic resonance images are not a causal explanation of pain because a high rate of asymptomatic subjects (63%) had comparable morphologic findings. The only highly significant difference between the study group and control group regarding morphologic findings was the criteria of a nerve root compromise. Work perception
and psychosocial factors
were helpful in discriminating between symptomatic and asymptomatic disc herniations.