Table 6.

Head trauma prior to reference date

Characteristics	% of cases (n = 45)	% of controls (n = 95)	Adjusted* odds ratio		Missing no.		P for trend
			Estimate	95% CI	Cases	Controls
No. head injuries					0	0	0.9
0	71.1	69.7	1.0	Reference
1	17.8	16.7	1.3	0.4–3.7
2	6.7	10.3	0.6	0.1–2.7
3+	4.4	3.4	1.4	0.1–14.2
With loss of consciousness	11.1	10.5	1.0	0.3–3.8	0	0
Had medical treatment	13.3	21.4	0.8	0.2–2.4	0	0
With pierced skull	0.0	2.3	0.0	0.0–Inf	0	0
With skull fracture	0.0	0.6	0.0	0.0–Inf	0	0
Had stitches	8.9	8.1	2.3	0.5–9.7	0	0
Had surgery	0.0	0.9	0.0	0.0–Inf	0	0
With residual disability	2.2	0.0	Inf	0.0–Inf	0	0

CI, confidence interval.

^*Adjusted for African-American race, annual income (four categories, multiply imputed).