Twelve studies were included in this review having met the required standards of methodological rigour: 7 RCTs (832 patients) and 5 quasi-experimental studies (294 patients). The authors reported that a number of the included studies claiming to have used randomisation had not reported the methods used, and 6 studies were included in the review with caution following the methodological quality assessment. Sample sizes ranged from 20 to 200 participants.
Psychological indicators of pre-procedural state anxiety.
Data were available on psychological responses for 9 studies, all of which used the Spielberger State Trait Anxiety Index outcome measure. Five of the studies with unpaired data (8 studies) reported a significant reduction in anxiety in patients listening to music compared with a control. Three of the studies with paired data (5 studies) reported a significant reduction in anxiety following music listening.
Pre-procedural physiological status outcomes.
Blood pressure: 10 studies reported blood-pressure readings. Studies with unpaired data (5 studies) found no significant differences. Three of the studies with paired data (4 studies) found significant post-intervention reductions in systolic blood-pressure; a fourth found reductions but not of statistical significance.
Pulse rate: 9 studies reported data on pulse rate and music listening. One of the studies with unpaired data (8 studies) reported a significant reduction in the intervention group. For studies with paired data (6 studies), a variety of conflicting results were found with no clear statistical trend for increase or decrease in either the control or intervention group.
Respiration rate: 6 studies reported data on this outcome. Three of the studies with unpaired data (5 studies) found a significant decrease in the respiration rate of patients listening to music compared with controls. Three of the studies with paired data (4 studies) reported significant reductions in respiration rate for music listening patients.
Heart rate variability analysis: one study found that heart rate variability significantly changed in the intervention group, indicating increased vagal tone and relaxation.