Table 2.

Incidence of HIZ on lumbar MR images in various age groups (n = 637)

Age group (years)	HIZ			Total
	Present	Absent	Incidence rate (%)
< 20	3	23	11.54	26
20–29	4	47	7.84	51
30–39	28	63	30.77	91
40–49	55	99	35.71	154
50–59	54	88	38.03	142
60–69	33	54	37.93	87
70–79	20	53	27.40	73
> = 80	4	9	30.77	13

χ² = 24.340, P = 0.001