Systematic Review of Lumbar Provocation Discography in Asymptomatic Subjects with a Meta-analysis of False-positive Rates

Background: Lumbar provocation discography is a controversial diagnostic test. Currently, there is a concern that the test has an unacceptably high false-positive rate. Study Design: Systematic review and meta-analysis. Objective: To perform a systematic review of lumbar discography studies in asymptomatic subjects and discs with a meta-analysis of the specificity and false-positive rate of lumbar discography. Methods: A systematic review of the literature was conducted via a PUBMED search. Studies were included/excluded according to modern discography practices. Study quality was scored using the Agency for Healthcare Research and Quality (AHRQ) instrument for diagnostic accuracy. Specific data was extracted from studies and tabulated per published criteria and standards to determine the false-positive rates. A meta-analysis of specificity was performed. Strength of evidence was rated according to the AHRQ U.S. Preventive Services Task Force (USPSTF) criteria. Results: Eleven studies were identified. Combining all extractable data, a false-positive rate of 9.3% per patient and 6.0% per disc is obtained. Data pooled from asymptomatic subjects without low back pain or confounding factors, shows a false-positive rate of 3.0% per patient and 2.1% per disc. In data pooled from chronic pain patients, asymptomatic of low back pain, the false-positive rate is 5.6% per patient and 3.85% per disc. Chronic pain does not appear to be a confounding factor in a chronic low back pain patient’s ability to distinguish between positive (pathologic) and negative (non-pathologic) discs. Among additional asymptomatic patient subgroups analyzed, the false-positive rate per patient and per disc is as follows: iliac crest pain 12.5% and 7.1%; chronic neck pain 0%; somatization disorder 50% and 22.2%, and, post-discectomy 15% and 9.1%, respectively. In patients with chronic backache, no false-positive rate can be calculated. Low-pressure positive criteria (≤ 15 psi a.o.) can obtain a low false-positive rate. Based on meta-analysis of the data, using the ISIS standard, discography has a specificity of 0.94 (95% CI 0.88 – 0.98) and a false-positive rate of 0.06. Conclusions: Strength of evidence is level II-2 based on the Agency for Healthcare Research Quality (USPSTF) for the diagnostic accuracy of discography. Contrary to recently published studies, discography has a low false-positive rate for the diagnosis of discogenic pain. Key words: Meta-analysis, lumbar discography, false-positive, asymptomatic subjects