Introduction: We have shown that an IL6 haplotype (GGGA) associates with intervertebral disc disease (IDD) characterized by sciatica. However, its prognostic value for IDD is not known.

Materials and methods: DNA from 153 sciatica patients, who participated in a randomized controlled trial of periradicular infiltration, was analyzed for IL6 variations: c.1–597G> A, c.1–572G> C, c.1–174G> C, and c.486T> A (Genebank #NM_000600.1). Patients recorded back and leg pain intensity and duration (number of days with pain), Oswestry disability, and back-related sick leaves. Repeated measures ANCOVA with adjustment for age, gender and physical work load was used. Square root transformations of outcome data at one, two and three years after the intervention were used for skewed variables.

Results: The prevalence of the GGGA haplotype was 9% (14/153). Data was available from 10 (sick leaves) to 13 (VAS) subjects with and from 107 to 124 subjects without the haplotype. The groups did not differ with respect to pain intensities, or disability. Days with back and leg pain and sick leaves were significantly higher among subjects with the IL6 haplotype (p=0.024, 0.002 and 0.022, respectively). An interaction of the IL6 haplotype and physical work load was significant for duration of back and leg pain and sick leaves (p=0.010, 0.004 and 0.018, respectively).

Discussion: This is the first observation of any prognostic genotype among sciatica patients. The IL6 haplotype GGGA predicted the number of days with back or leg pain, and sickness absence. Subjects with the IL6 haplotype may be more vulnerable when exposed to physically demanding job.