The potential value of blood biomarkers of intervertebral disk metabolism in the follow-up of patients with sciatica.

STUDY

DESIGN

This is a prospective study with a follow-up period of 4 years.

OBJECTIVES

The study aimed to evaluate the possible clinical utility of three biomarkers [i.e., keratan sulfate (KS), hyaluronan, and cartilage oligomeric matrix protein] measured in peripheral blood in severe acute sciatica at intake and follow-up.

SUMMARY OF

BACKGROUND

Our previous study and others have pointed out the interest of different laboratory tests in the acute phase of sciatica. Several blood biomarkers have been reported useful in the long-term follow-up of patients with osteoarthritis. We have found no information about the potential interest of these tests in spinal disorders.

METHODS

Patients were admitted to the hospital for intensive conservative management of acute sciatica (n=82). A subgroup of patients (n=33) was selected based on the duration of symptoms at visit 1, and included those with the shortest (n=24) as well as those with the longest (n=9) duration of sciatica. Blood samples were drawn, centrifuged, and the plasma frozen. Antigenic KS, hyaluronan, and cartilage oligomeric matrix protein were measured by ELISA. Patients were re-evaluated at an average of 4.3 years (range: 2.1-6.8 years).

RESULTS

Thirty-three subjects with an average age of 49.2+/-10.2 years participated. At intake, levels of the three biomarkers evaluated were within the range of normal values. No significant differences were found between the results of patients with a short history of sciatica (< or =3 weeks) and those with a long duration of symptoms (>20 weeks). At follow-up, a significant increase (P<0.05) in all three biomarkers was found.

CONCLUSIONS

A single measurement of these three biomarker molecules does not seem to have any diagnostic or therapeutic relevance in patients with acute radicular compression. The significance of the increase in all three biomarkers after a mean follow-up of 4.3 years is unclear; it might reflect metabolic processes involved in degenerative spinal disorders. Even though we found no correlation with clinical outcome, we believe that more research is needed.