Table 3.

Prevalence of nerve root impingement in people who do not have low back pain

Reference	Population studied	Numbers of subjects (number male)	Mean age (range)	Number of levels examined per person	Grade of nerve root impingement	Prevalence % (95% CI)
Boos et al, 199520	Volunteers from trauma clinic who had never consulted or been absent from work because of LBP	46 (34)	36 (20-50)	5	Contact or displacement	17% (8%-31%)
Jarvik et al, 200116	Patients with no LBP in the past 4 months that was more than mildly bothersome	148 (131)	54 (36 -71)	5	Compression Displacement or compression	4% (1%-15%) 3% (1%-8%)
Kjaer et al, 20056	Volunteers from general population with no LBP in past year	128 (NA*)	40 (40-40)	5	Displacement or compression	4% (1%-9%)
Savage et al, 19977	Volunteers from 5 occupations with no LBP in past year	70 (70)	NA* (≥20- ≤58)	5	Compression	3% (0%-10%)
Weishaupt et al, 199818	Volunteers referred for non-spinal imaging who had never consulted or been absent from work because of LBP	60 (30)	35 (20-50)	5	Contact Displacement Compression	23% (13%- 36%) 5% (1%-14%) 2% (0%-9%)
Carragee et al, 200642	Cervical disc disease patients with no history of LBP causing functional loss or requiring treatment	200 (119)	39 (NA*)	5	Contact Displacement or compression	11% (7%-15%) 3% (1%-6%)

^*NA = not available