Altering electromyography studies: importance of the electromyographer's perception of patient pain.

OBJECTIVE

To determine the relation between the patient's actual pain, the electromyographer's perception of patient pain, and whether an electromyogram (EMG) is altered.

DESIGN

Patients undergoing electromyography reported expected pain and procedure-related overall pain on a 100-mm visual analog scale (VAS). Blinded electromyographers estimated patient pain levels and indicated if they altered the study in any way because of this perception. Multivariable logistic regression was used to determine predictors of altering the EMG. Paired t tests were used to compare overall pain with expected pain and electromyographer perception of pain.

SETTING

Tertiary referral center.

PARTICIPANTS

Referred sample of adult subjects (N=304).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Patient pain, electromyographer perception of patient pain, and whether an EMG was altered because of the electromyographer's perception of patient pain.

RESULTS

Mean VAS scores ± SD were 48±25mm for patient-expected pain (P<.001), 42±24mm for electromyographer perception of pain (P<.0001), and 36±25mm for actual overall pain. Electromyographers altered their study 31.7% of the time because of concerns about pain. For every 13-mm increase on the VAS (a prespecified clinically meaningful difference), the electromyographer perception of pain increased the odds of altering a study 2.36 times (95% confidence interval [CI], 1.71-3.26), whereas patient overall pain did not have a significant effect (odds ratio=1.12; 95% CI, .86-1.47).

CONCLUSIONS

Patients expect EMGs to be more painful than they are. Electromyographers overestimate patient pain and are more likely to alter their studies when they believe patients are experiencing more pain, independently of whether patients actually have more pain. Improving the communication between electromyographers and patients may prevent unnecessary alterations.