Univariable and multivariable linear and logistic regression analyses of factors associated with spirometric outcomes (n=1721)
| Variables | FEV1 (L) | FVC (L) | FEV1/FVC (%) | CAO (n=74; 4%) | BDR with symptoms† (n=174; 10%) | |||||
| Unadjusted β (95% CI) | Adjusted β (95% CI) | Unadjusted β (95% CI) | Adjusted β (95% CI) | Unadjusted β (95% CI) | Adjusted β (95% CI) | OR (95% CI) | AOR (95% CI) | OR (95% CI) | AOR (95% CI) | |
| Age (years)‡ | ||||||||||
| Q1 (18–24) | Reference | Reference | Reference | Reference | Reference | Reference | 1.00 | – | 1.00 | 1.00 |
| Q2 (25–30) | −0.126 (−0.196 to 0.055) | −0.113 (−0.179 to 0.046) | −0.041 (−0.122, 0.04) | −0.032 (−0.107, 0.043) | −2 (−3 to 2) | −2 (−3 to 1) | 1.26 (0.59 to 2.69) | – | 0.88 (0.57 to 1.36) | 0.81 (0.51 to 1.28) |
| Q3 (31–37) | −0.264 (−0.335 to 0.192) | −0.227 (−0.304 to 0.150) | −0.117 (−0.2 to 0.034) | −0.101 (−0.187 to 0.014) | −5 (−5 to 4) | −4 (−5 to 3) | 1.49 (0.71 to 3.15) | – | 1.01 (0.65 to 1.55) | 0.76 (0.45 to 1.28) |
| Q4 (38–71) | −0.592 (−0.663 to 0.522) | −0.534 (−0.618 to 0.449) | −0.45 (−0.531 to 0.368) | −0.425 (−0.520 to 0.330) | −7 (−8 to 6) | −6 (−7 to 5) | 2.64 (1.36 to 5.13) | – | 0.89 (0.57 to 1.37) | 0.58 (0.32 to 1.05) |
| Height (cm) | 0.035 (0.03 to 0.039) | 0.036 (0.032, 0.04) | 0.046 (0.041 to 0.05) | 0.047 (0.043 to 0.051) | −0 (−0 to 0) | −0 (−0 to 0) | 1.02 (0.99 to 1.06) | – | 1.04 (1.01 to 1.07) | 1.04 (1.01 to 1.07) |
| Pack-years of smoking | ||||||||||
| None | Reference | Reference | Reference | Reference | Reference | Reference | 1.00 | 1.00 | 1.00 | 1.00 |
| <3.5 | 0.043 (−0.04 to 0.125) | 0.064 (−0.006 to 0.134) | 0.114 (0.022 to 0.206) | 0.12 (0.041 to 0.199) | −1 (−2 to 0) | −1 (−2 to 0) | 0.81 (0.34 to 1.91) | 0.86 (0.36 to 2.07) | 1.62 (1.05 to 2.52) | 1.65 (1.06 to 2.57) |
| ≥3.5 | −0.329 (−0.411 to 0.248) | −0.143 (−0.216 to 0.069) | −0.203 (−0.293 to 0.112) | −0.066 (−0.149 to 0.017) | −5 (−6 to 4) | −3 (−4 to 2) | 3.37 (2.00 to 5.66) | 2.72 (1.54 to 4.81) | 1.80 (1.19 to 2.73) | 1.88 (1.19 to 2.96) |
| Duration of employment in textile industry (years)‡ | ||||||||||
| Q1 (0–4) | Reference | Reference | Reference | Reference | Reference | Reference | 1.00 | 1.00 | 1.00 | 1.00 |
| Q2 (5–9) | −0.07 (−0.146 to 0.006) | −0.027 (−0.098 to 0.044) | −0.048 (−0.134 to 0.037) | −0.025 (−0.105 to 0.055) | −1 (−2 to 0) | −0 (−1 to 1) | 0.82 (0.37 to 1.83) | 0.99 (0.42 to 2.31) | 1.03 (0.65 to 1.63) | 1.08 (0.67 to 1.74) |
| Q3 (10–16) | −0.185 (−0.258 to 0.112) | −0.07 (−0.147 to 0.007) | −0.115 (−0.198 to 0.032) | −0.055 (−0.142 to 0.032) | −2 (−3 to 2) | −1 (−2 to 0) | 1.36 (0.68 to 2.73) | 1.61 (0.74 to 3.53) | 1.06 (0.68 to 1.65) | 1.14 (0.69 to 1.89) |
| Q4 (17–46) | −0.433 (−0.508 to 0.357) | −0.112 (−0.206 to 0.018) | −0.315 (−0.4 to 0.23) | −0.087 (−0.193 to 0.019) | −5 (−6 to 4) | −1 (−2 to 0) | 2.26 (1.17 to 4.33) | 2.34 (1.04 to 5.26) | 1.22 (0.79 to 1.91) | 1.35 (0.74 to 2.47) |
| Section of mill | ||||||||||
| Weaving | Reference | Reference | Reference | Reference | Reference | Reference | 1.00 | 1.00 | 1.00 | 1.00 |
| Spinning | −0.109 (−0.163 to 0.054) | −0.147 (−0.202 to 0.092) | −0.126 (−0.187 to 0.066) | −0.137 (−0.199 to 0.075) | −0 (−1 to 0) | −1 (−2 to 0) | 2.61 (1.58 to 4.32) | 2.67 (1.60 to 4.46) | 1.09 (0.80 to 1.49) | 1.09 (0.80 to 1.49) |
| Job title | ||||||||||
| Supervisor | Reference | Reference | Reference | Reference | Reference | Reference | 1.00 | 1.00 | 1.00 | – |
| Technician | 0.096 (−0.031 to 0.223) | 0.018 (−0.089 to 0.125) | 0.084 (−0.056 to 0.224) | 0.057 (−0.064 to 0.178) | 1 (−1 to 3) | −1 (−2 to 1) | 0.78 (0.28, 2.16) | 0.99 (0.35 to 2.81) | 0.89 (0.44 to 1.79) | – |
| Machine operator | 0.094 (−0.012 to 0.22) | 0.02 (−0.072 to 0.112) | 0.065 (−0.052 to 0.182) | 0.072 (−0.031 to 0.176) | 1 (0, 3) | −1 (−2 to 0) | 0.74 (0.32 to 1.68) | 1.24 (0.53 to 2.93) | 0.84 (0.47 to 1.49) | – |
| Cleaner | 0.094 (−0.023 to 0.21) | −0.026 (−0.133 to 0.082) | 0.036 (−0.093 to 0.165) | 0.038 (−0.084 to 0.159) | 2 (0 to 3) | −2 (−3 to 0) | 0.89 (0.36 to 2.20) | 1.96 (0.70, 5.49) | 0.90 (0.48 to 1.70) | – |
| Working hours | ||||||||||
| ≤8 | Reference | Reference | Reference | Reference | Reference | Reference | 1.00 | – | 1.00 | – |
| >8 | −0.003 (−0.062 to 0.057) | −0.065 (−0.124 to 0.006) | 0.009 (−0.056 to 0.075) | −0.067 (−0.133 to 0.001) | −0 (−1 to 0) | −0 (−1 to 0) | 0.82 (0.49 to 1.39) | – | 1.07 (0.76 to 1.50) | – |
All variables in the multivariable models are mutually adjusted; blank cells represent covariables that were dropped in the process of stepwise model building.
*Postbronchodilator FEV1/FVC ratio below LLN.
†BDR and presence of composite respiratory variable (includes chronic cough, chronic phlegm, increased cough and phlegm during last 3 years, wheezing, chest tightness current, breathlessness grades 1, 2 or 3) and/or self-reported asthma.
‡Continuous variables were converted into quartiles; Q1–Q4 correspond to the cut-off values for each quartile.
AOR, adjusted OR; BDR, bronchodilator response; CAO, chronic airflow obstruction; FEV1, forced expiratory volume in first second; FVC, forced vital capacity; LLN, lower limit of normality.