Lumbar disk disease: epidemiology.

Sciatica is a common symptom that affects as many as 40% of the adult population at some time. However, clinically significant sciatica is much less common and occurs in only 4% to 6% of the population. Exactly how often the symptom is caused by lumbar disk herniation is uncertain; it is known that herniation can occur independent of symptoms. Among the factors associated with its occurrence are age, gender, occupation, cigarette smoking, and exposure to vehicular vibration. The contribution of other factors such as height, weight, and genetics is less certain. The majority of patients with sciatica appear to recover. Approximately 20% of patients with sciatica caused by lumbar herniation have a strong indication for surgical intervention. In the remainder, indications are based primarily on pain rather than functionally significant neurologic deficits. Because pain is the principle indication, there are wide variations in the rates of surgical intervention between countries, and, even within countries, there are significant regional variations. These variations appear to be driven less by specific medical factors and more by gender, occupation, income, education, and the surgeon's preference. Although the contribution of sciatica to low back pain disability remains uncertain, disability caused by low back pain and sciatica appears to be increasing at a rate disproportionate to population growth. To what degree surgery now contributes to that disability is uncertain, but limited information suggests that it may be substantial.