Review by: Dr. James Fernandez and Dr. Sepand Salehian

Click to listen to the accompanying podcast (discussion of this article begins at 19:15)
A group of 75 asymptomatic or minimally symptomatic for low back pain were enrolled in a study for provocative discography involving L3-S1 disc spaces.  The subjects were recruited from one of three patient pools: those having documented cervical disease, subjects with previous lumbar disc herniation with complete symptom resolution, and subjects with no history of cervical or lumbar disc illness but with a history of somatization disorder.  Another 75 matched subjects from the same subject pools who did not have discography performed were utilized as control subjects.

After the 75 subjects underwent discography, both groups were followed for up to 10 years. Primary outcomes measured were any reported imaging or surgical intervention; and secondary outcomes measured any low back pain events occurring 6 months prior to the interview, serious low back pain episodes, disability due to back pain, or medical visits for evaluation and treatment of back pain.

In terms of primary outcome measures, as defined by this study, the results were reported as follows:

By 10-years follow-up, there were 16 lumbar surgeries performed in 11 subjects in the discography group and 4 surgeries in 3 subjects in the control group; resulting in a number needed to harm value (NNH value) of 7.3.

At 10 years after enrollment, 21 discography subjects and 11 control subjects had new CT or MRI evaluations for the clinical evaluation of low back pain and/or lower extremity radiculopathy. Based on these data, the number needed to harm (NNH) for 12 provocative lumbar discography with respect to new lumbar imaging is 6.2.

In reading this paper, we reached the following conclusions:

1. The aggregate of those patients who have undergone provocative discography incur more lumbar spine surgery; more lumbar spine imaging; and more adverse events related to the lower back.  Results indicate a higher risk of surgery, advanced imaging, serious pain episodes, medical evaluations and work loss.
2. In 2013, 70,000 patients underwent provocative discography.  If the number needed to harm (NNH) for provocative lumbar discography with respect to lumbar surgery occurs at a rate of 7.3 as discussed in the article, and if this number is applied to the general population who have undergone this procedure, then the predicted total number of patients who would undergo lumbar surgery as a unintended negative result of provocative discography may be approximated at 9600.
3. Disc puncture and pressurized injection accelerates clinical disc disease in exposed patients

Cuellar, J., M. Stauff, R. Herzog, J. Carrino, G. Baker, and E. Carragee. “Does provocative discography cause clinically important injury to the lumbar intervertebral disc? A ten-year matched cohort study.” The spine journal: official journal of the North American Spine Society (2015).