Table 3. Fracture incidence rate per 1000 female-years and the incidence of fracture during 5 years of follow-up in the whole population according to the selected categories of FNBMD, NSA and age, and the possible combinations of FNBMD and NSA categories.

Risk factors	Subjects exposed to the risk	Hip fractures
	n	n	5 year incidence (%)	1000 female-year incidence rate (95% CI)
Age <65 years	469	13	2.77 a	5.5 (2.5–8.5)
Age ≥65 years	260	32	12.31 a'	26.1 (17.2–35.1)
H-FNBMD	445	7	1.57 b	3.2 (0.8–5.5)
L-FNBMD	284	38	13.38 b'	29.0 (19.9–38.1)
N-NSA	342	12	3.51 c	7.2 (3.1–11.2)
W-NSA	387	33	8.52 c'	16.7 (11.1–22.4)
N-NSA+H-FNBMD	215	2	0.93 d	1.9 (−0.7–4.4)
N-NSA+L-FNBMD	127	10	7.87 e	15.7 (6.1–25.4)
W-NSA+H-FNBMD	230	5	2.17 f	4.3 (0.5–8.2)
W-NSA+L-FNBMD	159	28	17.61 g	35.2 (22.4–48.0)

CI, confidence interval; H-FNBMD, higher femoral neck bone mineral density; L-FNBMD, lower femoral neck bone mineral density; N-NSA, narrower neck–shaft angle; ns, not significant; W-NSA, wider neck–shaft angle.

Fisher's exact test for differences in % of incident hip fractures in 5 years: a vs a', p=0.001; b vs b', p=0.001; c vs c', p=0.008; d vs f, ns; e vs g, p=0.014; f vs g, p=0.001; d vs e, p=0.001; e vs f, p=0.014. BMD cut-off value=0.638 g cm^–2, corresponding to the T-score value of −2.6; NSA cut-off value=123.97°; age cut-off value=65 years.