The clinician effect on "objective" technical components of the electrodiagnostic consultation.

OBJECTIVE: To examine the impact of clinician factors on technical data within an electrodiagnostic consultation for low-back pain and spinal stenosis.

DESIGN: Examiner differences on single-segment paraspinal mapping scores and other findings were examined in a prospective, masked, double-controlled trial involving 150 people aged 55-80 yrs who were selected for no symptoms, back pain, or possible spinal stenosis.

RESULTS: Unmasked clinicians were more variable than masked physicians (F2,219 = 4.808, P =or<0.01) and gave lower scores to people they felt had mechanical back pain. The percentage of inadequate segmental scores differed among clinicians (0-16.6%, F8,226 = 4.170, P < 0.001), with fellows having more difficulty than faculty (11.76 +/- 32.38% vs. 0.75 +/- 8.67%) (t233 = 3.753, P < 0.001). Correction of clinician bias improved the relationship between paraspinal score and subjects' ability to walk (weighted regression R = 0.129, B = -0.047, P < 0.001; unweighted regression R = 0.090, B = -0.045, P < 0.001).

CONCLUSIONS: Objective testing is adversely affected by clinician factors including prejudgment, experience, and individual idiosyncrasies. Less variation is found in more codified procedures. For electrodiagnostic consultation, correction of variability improves the relationship of test results to disability.