TABLE 5.

Mortality case count and incidence rate per 1,000 person years.

	Number of deaths	Person-years	MR per 1,000 person-year (95% CI)
Exposure to silica (N = 81)	28	391	71.4 (47.4–103.2)
No exposure to silica (N = 1,121)	232	5,340	43.4 (38.0–49.4)
Male patients (N = 162)
Exposure to silica (N = 38)	16	154	103.7 (59.3–168.4)
No exposure to silica (N = 124)	40	527	76.1 (54.3–103.6)
Female patients (N = 1,040)
Exposure to silica (N = 43)	12	237	50.5 (26.1–88.2)
No exposure to silica (N = 997)	192	4,813	39.9 (34.4–45.9)
Young patients < 50 years (N = 712)
Exposure to silica (N = 59)	14	305	45.9 (25.1–77.0)
No exposure to silica (N = 653)	110	3,211	34.2 (28.1–41.3)
Older patients ≥ 50 years (N = 490)
Exposure to silica (N = 22)	14	87	161.2 (88.1–270.3)
No exposure to silica (N = 468)	122	2,129	57.4 (47.6–68.4)
Disease duration < 5 year (N = 493)
Exposure to silica (N = 39)	13	151	86.1 (45.8–147.3)
Not exposure to silica (N = 454)	85	2,046	41.5 (33.2–51.4)
Disease duration ≥ 5 year (N = 709)
Exposure to silica (N = 42)	15	241	62.2 (34.8–102.7)
Not exposure to silica (N = 667)	147	3,294	44.6 (37.7–52.4)

The whole study sample contained 1,202 patients. MR, mortality rate.