Table 2.
Results of univariable and multivariable linear regression analysis for FVC (% predicted) *
| Variable | Univariable analysis | Multivariable analysis | ||
|---|---|---|---|---|
| Unadjusted coefficient estimate (95% CI) | P value | Adjusted coefficient estimate (95% CI) | P value | |
| Male sex | −4.80 (−11.52 to 1.92) | 0.16 | ||
| Age, years | −0.05 (−0.29 to 0.19) | 0.70 | ||
| BMI | 0.49 (0.00 to 1.00) | 0.05 | 0.61 (0.13 to 1.10) | 0.01† |
| Alcohol consumption | 6.89 (0.53 to 13.25) | 0.03† | 9.22 (3.06 to 15.38) | <0.01† |
| Highest level of education‡ | Linear coefficient: −2.29 (−8.81 to 4.24) | 0.49 | ||
| Quadratic coefficient: −3.57 (−10.69 to 3.56) | 0.32 | |||
| Cubic coefficient: −4.43 (−12.11 to 3.25) | 0.26 | |||
| HIV status | Positive: 7.33 (−1.75 to 16.42) | 0.11 | ||
| Unknown: −2.26 (−15.36 to 10.84) | 0.73 | |||
| Respiratory disease diagnosis | Yes: −9.61 (−21.86 to 2.64) | 0.12 | ||
| Unknown: 5.96 (−13.56 to 25.48) | 0.55 | |||
| mMRC Score‡ | Linear: −2.87 (−10.98 to 5.24) | 0.48 | ||
| Quadratic: 11.15 (−0.03 to 22.34) | 0.05 | |||
| Cubic: 1.57 (−8.55 to 11.69) | 0.76 | |||
| 6MWD, m | 0.00 (−0.02 to 0.05) | 0.62 | ||
| Chronic cough for at least 3 months per year | −8.88 (−17.82 to 0.06) | 0.05 | ||
| Chronic bronchitis symptoms§ | Present: −8.16 (−16.35 to 0.04) | 0.05 | −10.35 (−18.28 to −2.41) | 0.01† |
| Unknown: −12.37 (−29.20 to 4.46) | 0.15 | Unknown: −14.68 (−30.69 to 1.32) | 0.07 | |
| Number of times treated for TB (1, 2, ≥3) | Linear coefficient: −1.50 (−9.55 to 6.55) | 0.71 | ||
| Quadratic coefficient: −2.67 (−9.64 to 4.30) | 0.45 | |||
| Age at first TB, years | −0.02 (−0.27 to 0.22) | 0.84 | ||
| Ever not completed treatment | −1.75 (−14.87 to 11.38) | 0.79 | ||
| Ever had MDR/XDR-TB | −10.99 (−30.54 to 8.56) | 0.27 | ||
| Smoking status | Ex: 3.03 (−10.31 to 16.37) | 0.65 | ||
| Never: 2.87 (−4.40 to 10.14) | 0.44 | |||
| Ever smoked substance other than cigarettes | 3.56 (−3.15 to 10.27) | 0.30 | 5.06 (−1.33 to 11.44) | 0.12 |
| Any prolonged (>15 h) exposure to vapours, dusts, gases or fumes at home or in job | −0.78 (−7.61 to 6.04) | 0.82 | ||
| Final model fit | Adjusted R2: 0.14 | AIC: 594 | ||
* Variables were included based on exposures of interest and possible confounders. Statistically significant variables as per final backwards multivariable regression analysis. For binary variables, the other group is the comparator.
† P < 0.05.
‡ mMRC and education level treated as ordinal categorical values.
§ Defined as productive cough for at least 3 months in the previous 2 years.
FVC = forced vital capacity; CI = confidence interval; BMI = body mass index; mMRC = modified medical research council; 6MWD = 6-minute walking distance; MDR-TB = multidrug- resistant; XDR-TB = extensively drug-resistant TB; AIC = Akaike Information Criterion.