Table 5. Odds ratio (95% CIs) of hip fractures for quartiles of seafood stratified by gender, source of controls, and fracture sites in Guangzhou, China.

		Quartiles of dietary energy-adjusted intake				p-trend	p-intera -ction
Variable	Pair N	1 (referent)	2	3	4 (highest)
Freshwater fish
Gender							0.189
Male	148	1.00	1.09(0.19–6.38)	1.82(0.29–11.38)	2.30(0.41–12.82)	0.270
Female	433	1.00	0.82(0.47–1.43)	1.08(0.60–1.95)	0.52(0.28–0.97)	0.212
Source of controls							0.143
Community	398	1.00	1.07(0.56–2.03)	1.76(0.90–3.45)	1.21(0.60–2.46)	0.510
Hospital	183	1.00	1.35(0.64–2.87)	1.01(0.47–2.19)	0.60(0.26–1.38)	0.215
Sea fish
Gender							0.052
Male	148	1.00	0.24(0.06–1.02)	0.03(0.01–0.19)	0.10(0.02–0.47)	0.015
Female	433	1.00	0.86(0.51–1.48)	0.72(0.40–1.29)	0.36(0.18–0.69)	0.003
Source of controls							0.768
Community	398	1.00	0.47(0.25–0.90)	0.34(0.17–0.68)	0.29(0.14–0.58)	<0.001
Hospital	183	1.00	0.75(0.35–1.60)	0.30(0.13–0.68)	0.18(0.06–0.54)	<0.001
Mollusca and shellfish
Gender							0.540
Male	148	1.00	0.51(0.09–2.74)	0.89(0.17–4.61)	0.08(0.01–1.37)	0.252
Female	433	1.00	1.00(0.59–1.69)	0.47(0.26–0.87)	0.59(0.32–1.06)	0.016
Source of controls							0.403
Community	398	1.00	0.37(0.20–0.69)	0.39(0.20–0.77)	0.59(0.31–1.12)	0.039
Hospital	183	1.00	0.54(0.25–1.17)	0.34(0.15–0.79)	0.25(0.09–0.68)	0.002
Total fish
Gender							0.864
Male	148	1.00	1.24(0.29–5.41)	2.10(0.41–10.73)	0.41(0.07–2.43)	0.665
Female	433	1.00	1.06(0.61–1.86)	1.18(0.65–2.12)	0.42(0.22–0.78)	0.037
Source of controls							0.389
Community	398	1.00	0.86(0.50–1.66)	1.19(0.58–2.44)	0.57(0.28–1.15)	0.200
Hospital	183	1.00	0.95(0.47–1.91)	1.36(0.63–2.91)	0.25(0.09–0.70)	0.075

Odds ratios (95% CI): from multivariate conditional logistic regression models. Covariates adjusted for: see ORII in Table 3. For women, years since menopause, oral contraceptive user, estrogen user were further adjusted for by the stepwise forward method.