Table 2.

Incidence Rates and Cumulative Incidence for First VTE, by Genotype

Characteristic	Genotype
	All genotypes (n = 1523)	SS/Sβ0- thalassemia (n = 832)	SS-α-thalassemia (n = 301)	SC/Sβ+- thalassemia (n = 390)
Duration of follow-up
Mean (SD), years	5.9 (2.2)	5.6 (2.4)	6.8 (1.4)	5.8 (2.2)
Age at first VTE
Mean (SD), years	28.6 (8.4)	27.8 (7.3)	27.5 (9.3)	39.4 (14.0)
Age range at first VTE, years	17–55	18–47	17–45	30–55
Incidence Rate, per 1000 person-years (CI)
Total VTE events	5.2 (3.8–6.9)	7.6 (5.3–10.6)	4.0 (1.7–7.8)	1.3 (0.3–3.9)
PE events	3.6 (2.5–5.1)	5.4 (3.5–8.0)	2.5 (0.8–6.0)	0.9 (0.1–3.2)
DVT events	1.9 (1.1–3.1)	2.4 (1.2–4.3)	2.0 (0.5–5.1)	0.9 (0.1–3.2)
Cumulative Incidence (%, CI)
by age 30	7.4 (5.2–10.3)	10.4 (7.1–15.0)	5.8 (2.4–13.7)	1.1 (0.2–7.4)
by age 40	11.3 (8.3–15.3)	15.9 (11.2–22.3)	10.0 (4.5–21.4)	2.5 (0.6–9.9)
Hazard Ratio (CI)*	--	1.00	0.52 (0.24–1.13)	0.18 (0.05–0.58)

^*Adjusted for sex. SD = standard deviation, CI = 95% confidence interval, DVT = deep venous thrombosis, PE= pulmonary embolism, VTE = venous thromboembolism