Case-control study of risk factors for lumbar intervertebral disc herniation in Croatian island populations.

AIM To investigate the risk factors for lumbar intervertebral disc herniation (L4/L5 or L5/S1) severe enough to require surgery of the lower spine among 9 isolated populations of Croatian islands and to evaluate predictive value, sensitivity, and specificity of a simple screening test based on the understanding of the risk factors in this population. METHODS In a sample of 1001 examinees from Croatian island populations, we identified all subjects who underwent surgery of the lower spine due to lumbar intervertebral disc herniation L4/L5 or L5/S1 and selected 4 controls matched by age, gender, and village of residence for each of them. Odds ratio was computed for the following variables: body mass index, occupation, intensity of physical labor at work, intensity of physical labor at home, smoking index, claudication index, self-assessed limitation in physical activity, level of education, socio-economic status, and family history of lumbar intervertebral disc herniation requiring surgery. RESULTS Comparison of 67 identified cases with 268 controls revealed the highest odds ratios (OR) for positive family history (OR 4.00; 95% confidence intervals [CI], 1.89-6.11, P<0.001), intensity of physical labor at work defined as (hard) (OR 2.94; 95% CI, 1.07-4.81, P<0.001), and body mass index of 25.7 or more (OR 2.77, 95% CI, 1.05-4.49, P=0.002). A simple screening test based on the presence of any two of these three criteria has 74% sensitivity and 82% specificity to detect persons who underwent lower spine surgery due to lumbar intervertebral disc herniation in the population aged 40 years or more. CONCLUSION Occurrence of lumbar disk herniation severe enough to require surgery of the lower spine can be predicted using a very simple set of criteria. This type of screening could reduce the need for surgery in isolated communities through prevention within primary health care.