Concordance of near infrared spectroscopy with pressure flow studies in men with lower urinary tract symptoms.

PURPOSE: Near infrared spectroscopy is a technology with the potential to diagnose bladder outlet obstruction noninvasively. We investigated the correlation between the near infrared spectroscopy algorithm classification of obstructed or unobstructed (based on near infrared spectroscopy pattern, maximum flow rate and post-void residual) and pressure flow studies in men with lower urinary tract symptoms. We also assessed whether the near infrared spectroscopy pattern itself, independent of the near infrared spectroscopy algorithm (which also includes maximum flow rate and post-void residual urine), correlates with bladder outlet obstruction.

MATERIALS AND

METHODS

Subjects simultaneously underwent urodynamics and near infrared spectroscopy evaluation. Bladder outlet obstruction classification was based on the International Continence Society nomogram. The near infrared spectroscopy algorithm was evaluated against the comparable noninvasive algorithms with receiver operating characteristic curves. For significance the Mann-Whitney U test was used with p<0.05 considered significant.

RESULTS

Of 42 subjects 33 (79%) had evaluable data. Area under the curve was 0.484 for the near infrared spectroscopy algorithm relative to pressure flow diagnosis. A downward near infrared spectroscopy pattern is associated with obstruction whereas an upward pattern is associated with nonobstruction. Of 26 patients with urodynamic bladder outlet obstruction 9 (35%) had a downward, 4 (15%) a flat and 13 (50%) an upward near infrared spectroscopy pattern. Of 7 unobstructed cases 4 (57%) had a downward, 1 (14%) a flat and 2 (29%) an upward near infrared spectroscopy pattern.

CONCLUSIONS

The near infrared spectroscopy algorithm had a 0.484 AUC for diagnosing bladder outlet obstruction. The near infrared spectroscopy pattern component itself did not correlate strongly. The near infrared spectroscopy algorithm does not appear to provide substantial clinical usefulness in diagnosing bladder outlet obstruction in men with lower urinary tract symptoms. More studies are needed to further define and validate uses for near infrared spectroscopy in urology.