Table 2. Hazard ratios (HR) for the composite endpoint, all-cause mortality, and cause specific hazard (CSH) ratio for impaired lung function in relation to occupational endotoxin exposure in the entire cohort (n=919, 414 men, 505 women).
Hazards calculated using the Cox proportional hazards model accounting for left censoring and left truncation. Endotoxin exposure was modeled as either cotton vs. silk textile work, or lifetime occupational endotoxin exposure as a time varying covariate. Hazard ratios were adjusted for gender and height as non-time varying covariates, and for years worked in the textile industry, age, and lifetime pack-years smoked as time varying covariates.
| FEV1 at fifth percentile1 | All-cause mortality | Composite endpoint1,2 | ||||
|---|---|---|---|---|---|---|
| Events | CSH (95% CI) | Events | HR (95% CI) | Events | HR (95% CI) | |
| Cotton vs. silk | ||||||
| All | 164/919 | 1.36 (0.93-2.00) | 128/919 | 1.36 (0.93–1.99) | 253/919 | 1.47 (1.09–1.97) |
| Males | 106/414 | 1.42 (0.89-2.28) | 89/414 | 1.63 (1.04–2.57) | 163/414 | 1.84 (1.27–2.67) |
| Females | 58/505 | 1.26 (0.67-2.38) | 39/505 | 0.92 (0.48–1.77) | 90/505 | 1.00 (0.62–1.61) |
| Occupational endotoxin (per 10,000 EU/m3-yrs) | ||||||
| All | - | 1.04 (0.99-1.08) | - | 1.04 (0.99–1.08) | - | 1.04 (1.01–1.07) |
| Males | - | 1.03 (0.99-1.08) | - | 1.04 (1.00–1.08) | - | 1.05 (1.01–1.08) |
| Females | - | 1.05 (0.94-1.18) | - | 1.00 (0.89–1.14) | - | 1.00 (0.91–1.10) |
47 (28 men, 19 women) subjects were diagnosed with impaired lung function at the start of the study in 1981 and were effectively excluded from the analysis to address the issue of left censoring.
An event was defined as the earlier of either impaired lung function or death. 39 subjects (32 men, 7 women) were first diagnosed with impaired lung function and subsequently died during the follow-up period.