The relationship between history and physical examination findings and the outcome of electrodiagnostic testing in patients with sciatica referred to physical therapy.

STUDY

DESIGN

Cross-sectional diagnostic accuracy study.

OBJECTIVE

To investigate the relationship between history and physical examination findings and the outcome of electrodiagnostic testing in patients with sciatica referred to physical therapy.

BACKGROUND

Electrodiagnostic testing is routinely used to evaluate patients with sciatica. Recent evidence suggests that the presence of radiculopathy identified with electrodiagnostic testing may predict better functional outcomes in these patients. While some patient history and physical examination findings have been shown to predict the presence of disc herniation or neurological insult, little is known about their relationship to the results of electrodiagnostic testing.

METHODS

Electrodiagnostic testing was performed on 38 patients with sciatica who participated in a randomized trial that compared different physical therapy interventions. The diagnostic gold standard was the presence or absence of radiculopathy, based on the results of the needle electromyographic examination. Diagnostic sensitivity and specificity values were calculated, along with corresponding likelihood ratios, for select patient history and physical examination variables.

RESULTS

No significant relationship was found between select patient history and physical examination findings, analyzed individually or in combination, and the outcome of electrodiagnostic testing. Diagnostic sensitivity values ranged from 0.03 (95% confidence interval [CI]: 0.00, 0.24) to a high of 0.95 (95% CI: 0.72, 0.99), and specificity values ranged from 0.10 (95% CI: 0.02, 0.34) to a high of 0.95 (95% CI: 0.72, 0.99). Positive likelihood ratios ranged from 0.15 (95% CI: 0.01, 2.87) to a high of 2.33 (95% CI: 0.71, 7.70), and negative likelihood ratios ranged from 2.00 (95% CI: 0.35, 11.48) to a low of 0.50 (95% CI: 0.03, 8.10).

CONCLUSION

In this investigation, the relationship between patient history and physical examination findings and the outcome of electrodiagnostic testing among patients with sciatica was not found to be statistically significant or clinically meaningful. However, given the small sample size and corresponding large CIs, these results should be considered with caution, recognizing that some of the history and physical examination variables may prove useful in future research. These findings suggest that electrodiagnostic testing is essential to identify the subgroup of patients with sciatica who have measurable nerve injury consistent with radiculopathy, which may be an important prognostic factor for recovery. Level of Evidence Diagnosis, level 3b-. J Orthop Sports Phys Ther 2014;44(7):508-517. Epub 22 May 2014. doi:10.2519/jospt.2014.5002.