Univariable and multivariable logistic regression analyses of individual and workplace factors in association with respiratory symptoms and byssinosis (n=2031)
| Variables | n (%) | Chronic cough (n=267; 13%) | Chronic bronchitis* (n=158; 8%) | Chest tightness, current (n=307; 15%) | Composite respiratory variable† (n=1145; 56%) | Byssinosis‡ (n=60; 3%) | |||||
| OR (95% CI) | AOR (95% CI) | OR (95% CI) | AOR (95% CI) | OR (95% CI) | AOR (95% CI) | OR (95% CI) | AOR (95% CI) | OR (95% CI) | AOR (95% CI) | ||
| Age (years)§ | 30 (24–37)¶ | ||||||||||
| Q1 (18–24) | – | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | – |
| Q2 (25–30) | – | 1.12 (0.77 to 1.61) | 0.95 (0.64 to 1.40) | 1.4 (0.88 to 2.27) | 1.12 (0.66 to 1.89) | 0.96 (0.69 to 1.35) | 0.77 (0.53 to 1.12) | 1.07 (0.84 to 1.35) | 0.83 (0.63 to 1.09) | 1.30 (0.64 to 2.63) | – |
| Q3 (31–37) | – | 1.51 (1.0 to 2.16) | 0.95 (0.61 to 1.48) | 1.78 (1.11 to 2.85) | 0.87 (0.48 to 1.57) | 1.40 (1.01 to 1.94) | 0.84 (0.55 to 1.27) | 1.07 (0.84 to 1.35) | 0.61 (0.44 to 0.84) | 1.41 (0.69 to 2.88) | – |
| Q4 (38–71) | – | 1.34 (0.93 to 1.93) | 0.69 (0.42 to 1.13) | 1.63 (1.01 to 2.61) | 0.56 (0.28 to 1.10) | 0.80 (0.56 to 1.14) | 0.38 (0.23 to 0.62) | 1.25 (0.98 to 1.60) | 0.53 (0.37 to 0.76) | 0.99 (0.46 to 2.13) | – |
| BMI** | |||||||||||
| Normal | 892 (49.2) | 1.00 | – | 1.00 | – | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | – |
| Underweight (<18.5) | 269 (14.8) | 1.24 (0.85 to 1.81) | – | 0.99 (0.60 to 1.65) | – | 0.96 (0.67 to 1.40) | 0.92 (0.63 to 1.34) | 1.21 (0.92 to 1.61) | 1.13 (0.86 to 1.52) | 1.24 (0.59 to 2.59) | – |
| Overweight and obese (>23.9) | 654 (36.0) | 1.14 (0.86 to 1.52) | – | 1.23 (0.86 to 1.76) | – | 0.98 (0.74 to 1.28) | 1.00 (0.74 to 1.34) | 1.35 (1.10 to 1.67) | 1.32 (1.05 to 1.66) | 1.12 (0.63 to 1.98) | – |
| Pack-years of smoking | |||||||||||
| None | 1544 (76.0) | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |
| <3.5 | 239 (11.8) | 1.93 (1.35 to 2.76) | 1.82 (1.27 to 2.63) | 2.29 (1.48 to 3.55) | 2.25 (1.43 to 3.53) | 1.55 (1.09 to 2.20) | 1.43 (0.99 to 2.07) | 1.93 (1.45 to 2.58) | 1.77 (1.31 to 2.41) | 2.53 (1.35 to 4.76) | 2.47 (1.30 to 4.67) |
| ≥3.5 | 248 (12.2) | 2.09 (1.48 to 2.96) | 1.86 (1.28 to 2.71) | 2.80 (1.86 to 4.21) | 2.26 (1.43 to 3.59) | 1.56 (1.10 to 2.20) | 1.50 (1.03 to 2.21) | 2.87 (2.12 to 3.90) | 2.78 (1.96 to 3.93) | 1.53 (0.73 to 3.22) | 1.37 (0.63 to 2.99) |
| Duration of employment in the textile industry (years)§ | 9.0 (4.0–16.0)¶ | ||||||||||
| Q1 (0–4) | – | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |
| Q2 (5–9) | – | 1.30 (0.88 to 1.94) | 1.32 (0.86 to 2.03) | 1.86 (1.08 to 3.20) | 2.00 (1.09 to 3.65) | 1.23 (0.86 to 1.77) | 1.28 (0.85 to 1.92) | 1.42 (1.11 to 1.82) | 1.49 (1.11 to 1.98) | 0.84 (0.36 to 2.13) | 0.82 (0.35 to 1.95) |
| Q3 (10–16) | – | 1.48 (1.0 to 2.17) | 1.51 (0.96 to 2.39) | 2.07 (1.22 to 3.52) | 2.19 (1.15 to 4.18) | 1.54 (1.09 to 2.17) | 1.69 (1.09 to 2.61) | 1.70 (1.33 to 2.16) | 1.79 (1.30 to 2.47) | 1.59 (0.78 to 3.22) | 1.51 (0.70 to 3.27) |
| Q4 (17–46) | – | 2.14 (1.48 to 3.11) | 2.53 (1.48 to 4.33) | 3.24 (1.95 to 5.39) | 4.12 (1.96 to 8.65) | 1.57 (1.10 to 2.23) | 2.53 (1.49 to 4.29) | 1.99 (1.55 to 2.57) | 2.26 (1.52 to 3.35) | 1.52 (0.73 to 3.16) | 1.48 (0.63 to 3.45) |
| Section of mill | |||||||||||
| Weaving | 983 (48.4) | 1.00 | – | 1.00 | 1.00 | 1.00 | – | 1.00 | – | 1.00 | 1.00 |
| Spinning | 1048 (51.6) | 0.97 (0.75 to 1.25) | – | 1.13 (0.82 to 1.57) | 1.38 (0.97 to 1.95) | 1.01 (0.79 to 1.29) | – | 0.81 (0.68 to 0.96) | – | 1.07 (0.64 to 1.80) | 1.2 (0.71 to 2.03) |
| Job title | |||||||||||
| Supervisor | 154 (7.6) | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |
| Technician | 258 (12.7) | 1.11 (0.60 to 2.04) | 1.40 (0.75 to 2.63) | 0.99 (0.47 to 2.10) | 1.64 (0.73 to 3.68) | 1.08 (0.62 to 1.87) | 1.24 (0.68 to 2.27) | 1.03 (0.69 to 1.55) | 1.23 (0.77 to 1.96) | 0.89 (0.25 to 3.22) | 1.04 (0.29 to 3.82) |
| Machine operator | 1183 (58.2) | 1.24 (0.74 to 2.08) | 1.75 (1.01 to 3.00) | 1.09 (0.59 to 2.04) | 1.90 (0.93 to 3.86) | 1.06 (0.66 to 1.69) | 1.23 (0.74 to 2.07) | 0.90 (0.64 to 1.27) | 1.09 (0.73 to 1.61) | 1.28 (0.45 to 3.63) | 1.58 (0.54 to 4.61) |
| Cleaner | 436 (21.5) | 0.96 (0.54 to 1.70) | 1.80 (0.95 to 3.39) | 0.75 (0.37 to 1.53) | 2.16 (0.93 to 4.99) | 0.87 (0.52 to 1.47) | 1.44 (0.79 to 2.64) | 0.68 (0.47 to 0.99) | 1.17 (0.74 to 1.85) | 0.97 (0.30 to 3.10) | 1.48 (0.42 to 5.21) |
| Working hours | |||||||||||
| ≤8 | 1298 (63.9) | 1.00 | 1.00 | 1.00 | – | 1.00 | – | 1.00 | – | 1.00 | – |
| >8 | 733 (36.1) | 0.74 (0.56 to 0.98) | 0.70 (0.52 to 0.93) | 0.76 (0.53 to 1.08) | – | 0.86 (0.67 to 1.11) | – | 0.77 (0.64 to 0.92) | – | 0.82 (0.47 to 1.42) | – |
All variables in the multivariable models are mutually adjusted; blank cells represent covariables that were dropped in the process of stepwise model building
*Those having both cough and phlegm for 2 years or more.
†Includes participants reporting one or more of respiratory symptoms (chronic cough, chronic phlegm, increased cough and phlegm during last 3 years, wheezing, breathlessness grades 1, 2 or 3, and chest tightness).
‡WHO symptoms-based criteria.
§Continuous variables were converted into quartiles; Q1–Q4 correspond to the cut-off values for each quartile.
¶Median (IQR) reported.
**Data available for 34 mills (n=1815).
AOR, adjusted OR; BMI, body mass index.