Table 2

Characteristics of the cases with symptomatic osteochondrosis or spondylosis of the lumbar spine and control subjects

Characteristic		Cases with osteochondrosis or spondylosis and disc herniation (including disc herniations not verified by participating physicians, n=20)				Cases solely with osteochondrosis or spondylosis			Population controls (including controls recruited by random digit dialing)		Controls admitted to hospital for treatment of urolithiasis
Characteristic		n	%			n	%		n	%	n	%
Age at diagnosis (y):
⩽35	32	23.7		15	16.0		31	29.0	38	42.2
>35–40	23	17.0		8	8.5		14	13.1	12	13.3
>40–45	21	15.6		8	8.5		9	8.4	15	16.7
>45–50	26	19.3		15	16.0		19	17.8	6	6.7
>50–55	17	12.6		16	17.0		22	20.6	11	12.2
>55–60	9	6.7		28	29.8		10	9.3	6	6.7
>60	7	5.2		4	4.3		2	1.9	2	2.2
Mean age (y)	45.5			48.4			43.1		39.7
Educational level:
Graduated from high school	27	20.0		20	21.3		42	39.3	41	45.6
Secondary school level	36	26.7		14	14.9		30	28.0	22	24.4
Elementary level, no graduation	72	53.3		58	61.7		35	32.7	26	28.9
Unknown	—	—		2	2.1		—	—	1	1.1
Region:
Frankfurt, districts with ⩾35% blue collar workers	7	5.2		3	3.2		4	3.7	9	10.0
Frankfurt , districts with ⩾28–<35% blue collar workers	22	16.3		12	12.8		22	20.6	8	8.9
Frankfurt, districts with <28% blue collar workers	15	11.1		14	14.9		14	13.1	12	13.3
Hanau	25	18.5		17	18.1		11	10.3	21	23.3
Offenbach	14	10.4		25	26.6		26	24.3	2	2.2
Bad Homburg	5	3.7		3	3.2		6	5.6	4	4.4
Darmstadt	28	20.7		3	3.2		6	5.6	12	13.3
Offenbach county	13	9.6		12	12.8		18	16.8	14	15.6
Others	5	3.7		1	1.1		—	—	8	8.9
Unknown	1	0.7		4	4.3		—	—	—	—
Nationality:
German	105	77.8		67	71.3		84	78.5	62	68.9
Other	20	14.8		6	6.4		12	11.2	22	24.4
Unknown	10	7.4		21	22.3		11	10.3	6	6.7
Diseases potentially affecting lumbar discs:
None	64	47.4		40	42.6		84	78.5	70	77.8
Malposition of hip or pelvis, shortness of the leg, etc.	16	11.9		5	5.3		5	4.7	1	1.1
Scoliosis of lumbar spine	40	29.6		29	30.9		12	11.2	12	13.3
Malposition of hip or pelvis etc, and scoliosis	10	7.4		12	12.8		2	1.9	2	2.2
Unknown	5	3.7		8	8.5		4	3.7	5	5.6