Baseline characteristics
As shown in Table 1, the post-TB patient group included 1,466 patients (54.9%) with normal ventilation, 783 patients (29.3%) with obstructive ventilatory disorders, and 420 patients (15.8%) with restrictive ventilatory disorders. The mean ages of subjects with normal ventilation, obstructive ventilatory disorders, and restrictive ventilatory disorders were 53.4, 64.4, and 59.6 years, respectively (P < 0.001). The proportion of males was highest in subjects with obstructive ventilatory disorders, followed by those with restrictive ventilatory disorders and those with normal ventilation (76.2%, 52.0%, and 49.5%, respectively, P < 0.001). Subjects with obstructive ventilatory disorders had lower BMI than those with normal ventilation or restrictive ventilatory disorders (22.8 kg/m2, 23.7 kg/m2, and 23.8 kg/m2, respectively, P < 0.001). The proportion of subjects with low family income was highest in subjects with obstructive ventilatory disorders, followed by those with restrictive ventilatory disorders and those with normal ventilation (68.3%, 55.9%, and 43.0%, respectively, P < 0.001). The subjects with obstructive ventilatory disorders had the highest prevalence of asthma (10.9%), diabetes mellitus (19.1%), and hypertension (50.8%) among post-TB subjects, while subjects with restrictive ventilatory disorders had the highest prevalence of dyslipidemia (48.7%) and osteoporosis (11.9%) among the study population. Regarding spirometric results, FVC (L) and FVC %predicted were lowest in subjects with restrictive ventilatory disorders, while FEV1 (L), FEV1 %predicted, and FEV1/FVC were lowest in those with obstructive ventilatory disorders among post-TB subjects (P < 0.001 for all).
Table 1
Baseline characteristics of post-TB subjects by spirometric pattern
| Total (n = 2,669) | Normal ventilation (n = 1,466) | Obstructive ventilatory disorder (n = 783) | Restrictive ventilatory disorder (n = 420) | p value |
Age, years | 57.5 (56.7–58.3) | 53.4 (52.5–65.5) | 64.4 (63.2–65.5) | 59.6 (57.7–61.4) | < 0.001 |
Male | 57.7 (55.2–60.2) | 49.5 (45.9–53.1) | 76.2 (72.1–79.8) | 52.0 (45.2–58.8) | < 0.001 |
BMI, kg/m2 | 23.4 (23.3–23.6) | 23.7 (23.5–23.9) | 22.8 (22.5–23.1) | 23.8 (23.4–24.3) | < 0.001 |
Smoking history | | | | | < 0.001 |
Never-smoker | 48.2 (45.6–50.8) | 55.5 (51.8–59.2) | 28.2 (24.1–32.6) | 60.6 (53.5–67.2) | |
Current- or ex-smoker | 51.8 (49.2–54.4) | 44.5 (40.8–59.2) | 71.8 (67.4–75.9) | 39.4 (32.8–46.5) | |
Family income | | | | | < 0.001 |
Low | 52.1 (49.2–55.0) | 43.0 (39.2–46.8) | 68.3 (63.4–72.8) | 55.9 (49.0–62.6) | |
High | 47.9 (45.0–50.8) | 57.0 (53.2–60.8) | 31.7 (27.2–36.6) | 44.1 (37.4–51.0) | |
Education | | | | | < 0.001 |
High school or less | 79.1 (76.7–81.3) | 74.9 (71.6–78.0) | 86.5 (82.5–89.7) | 80.4 (73.9–89.7) | |
More than high school | 20.9 (18.7–23.3) | 25.1 (22.0–28.4) | 13.5 (10.1–17.5) | 19.6 (14.4–26.1) | |
Comorbidities | | | | | |
Asthma | 4.9 (3.9–6.1) | 2.3 (1.4–3.6) | 10.9 (8.3–14.1) | 2.8 (1.4–5.3) | < 0.001 |
Diabetes mellitus | 12.4 (10.7–14.3) | 8.3 (6.5–10.5) | 19.1 (15.5–23.4) | 15.0 (10.9–20.2) | < 0.001 |
Hypertension | 41.4 (38.7–44.1) | 35.0 (31.7–38.6) | 50.8 (45.7–55.8) | 47.2 (40.4–54.1) | < 0.001 |
Dyslipidemia | 44.1 (41.4–47.0) | 42.9 (39.2–46.7) | 44.5 (39.5–49.7) | 48.4 (41.5–55.3) | 0.413 |
Cardiovascular disease | 5.1 (4.0–6.5) | 4.5 (3.3–6.2) | 5.3 (3.5–7.9) | 7.3 (4.1–12.6) | 0.287 |
Osteoporosis | 8.2 (6.5–10.3) | 7.4 (5.5–10.3) | 7.7 (4.6–12.5) | 11.9 (7.3–19.0) | 0.297 |
Arthritis | 15.1 (13.4–16.9) | 15.4 (12.4–18.0) | 12.9 (10.3–16.0) | 18.3 (13.9–23.8) | 0.140 |
Depression | 4.5 (3.5–5.6) | 4.4 (3.2–6.1) | 4.6 (2.9–7.1) | 4.4 (2.4–7.7) | 0.993 |
Spirometry | | | | | |
FVC, L | 3.5 (3.4–3.5) | 3.7 (3.6–3.8) | 3.4 (3.3–3.5) | 2.7 (2.6–2.8) | < 0.001 |
FVC, % predicted | 88.7 (88.0–89.4) | 94.4 (93.6–95.1) | 85.5 (84.1–86.9) | 72.6 (71.5–73.7) | < 0.001 |
FEV1, L | 2.6 (2.5–2.6) | 2.9 (2.8–3.0) | 2.0 (2.0–2.1) | 2.1 (2.0–2.2) | < 0.001 |
FEV1, % predicted | 84.7 (83.8–85.5) | 94.4 (93.6–95.1) | 70.8 (69.3–72.4) | 74.3 (73.1–75.6) | < 0.001 |
FEV1/FVC | 73.3 (72.8–74.0) | 78.9 (78.6–79.3) | 60.6 (59.7–61.4) | 78.0 (77.2–78.7) | < 0.001 |
Data are presented as weighted mean (95% confidence interval) or weighted percentage (95% confidence interval).
TB, tuberculosis; BMI, body mass index; FVC, forced vital capacity; FEV1, forced expiratory volume in 1 second.
Comparison of symptoms, physical activity, and quality of life
As shown in Table 2, respiratory symptoms including sputum (18.2%, 15.1%, and 5.4%, respectively, P = 0.004) and dyspnea (3.8%, 2.4%, and 0.9%, respectively, P < 0.020) and physical activity limitations (27.7%, 13.0%, and 5.1%, respectively, P < 0.001) were most frequently observed in subjects with obstructive ventilatory disorders, followed by those with restrictive ventilatory disorders, and those with normal ventilation. Cough was observed most frequently in subjects with obstructive ventilatory disorders followed by those with restrictive ventilatory disorders or normal ventilation (11.6%, 5.4%, and 5.1%, respectively, P < 0.001).
Table 2
Comparison of symptoms, physical activity, and quality of life according to spirometric pattern
| Total (n = 2,669) | Normal ventilation (n = 1,466) | Obstructive ventilatory disorder (n = 783) | Restrictive ventilatory disorder (n = 420) | p value |
Any respiratory symptoms | 16.4 (14.0–19.3) | 12.4 (9.5–16.1) | 22.9 (18.1–28.5) | 18.6 (12.6–26.6) | 0.001 |
Cough | 7.3 (5.7–9.2) | 5.4 (3.5–8.3) | 11.6 (8.5–15.8) | 5.1 (2.8–9.3) | 0.004 |
Sputum | 13.0 (10.8–15.5) | 9.5 (7.0–12.8) | 18.2 (13.9–23.5) | 15.1 (9.5–23.2) | 0.004 |
Dyspnea | 2.0 (1.3–3.1) | 0.9 (0.3–2.5) | 3.8 (2.1–6.7) | 2.4 (0.9–5.9) | 0.020 |
Physical activity limitations | 15.6 (11.2–21.2) | 5.1 (2.3–10.9) | 27.7 (19.3–38.0) | 13.0 (6.2–28.4) | < 0.001 |
EQ-5D component | | | | | |
Mobility | 18.3 (16.4–20.3) | 14.0 (11.9–16.4) | 24.1 (20.4–28.1) | 23.5 (18.1–29.8) | < 0.001 |
Self-care | 5.2 (4.3–6.6) | 3.6 (2.6–5.0) | 7.7 (5.5–10.7) | 7.3 (4.3–12.4) | 0.005 |
Usual activity | 12.8 (11.1–14.6) | 9.4 (7.7–11.5) | 16.3 (13.1–20.1) | 19.1 (14.2–25.2) | < 0.001 |
Pain/discomfort | 29.0 (26.6–31.5) | 30.7 (26.5–35.2) | 30.1 (26.5–35.2) | 36.3 (29.8–43.4) | 0.015 |
Anxiety/depression | 13.6 (11.9–15.5) | 13.5 (11.3–16.1) | 13.5 (10.6–17.1) | 13.7 (9.5–17.5) | 0.999 |
EQ-5D index | 0.93 (0.92–0.93) | 0.94 (0.93–0.94) | 0.91 (0.90–0.93) | 0.91 (0.89–0.93) | 0.002 |
Data are presented as weighted mean (95% confidence interval) or weighted percentage (95% confidence interval).
EQ-5D, EuroQoL five dimensions.
The EQ-5D index values, denoting QoL, were lower among subjects with obstructive ventilatory disorders and restrictive ventilatory disorders than in those with normal ventilation (0.91, 0.91, and 0.94, respectively, P = 0.002). Regarding the individual EQ-5D component arm, subjects with obstructive ventilatory disorders had the highest rates of difficulty in mobility (24.1%, P < 0.001) and limitation in self-care (7.7%, P = 0.005) among post-TB subjects; however, those with restrictive ventilatory disorders had the highest rates of difficulty in usual activity (19.1%, P < 0.001) and pain/discomfort (36.3%, P = 0.015) among post-TB subjects (Table 2).
The impact of obstructive ventilatory disorder and its severity on respiratory symptoms, physical activity limitations, and EQ-5D index in post-TB subjects.
As shown in Table 3, subjects with obstructive ventilatory disorders had 1.68 (95% CI = 1.05–2.68) times more likely to have any respiratory symptoms compared to those with normal ventilation in the fully adjusted; additionally, it was specifically significant for sputum (aOR = 1.72, 95% CI = 1.34–3.39) and dyspnea (aOR = 4.41, 95% CI = 1.40–13.96). Likewise, subjects with obstructive ventilatory disorder had more physical activity limitations (aOR = 8.13, 95% CI = 2.95–22.41) compared to those with normal ventilation. Although subjects with obstructive ventilatory disorders were more likely to have a lower EQ-5D index compared to those with normal ventilation in the unadjusted model (coefficient = -0.021, 95% CI -0.036 – -0.069), this was not significant in the adjusted model.
Table 3
The impact of severity of obstructive ventilatory disorder on EQ-5D index value in post-TB subjects.
| Model | Normal (n = 1,466) | Obstructive ventilatory disorder | |
Overall (n = 783) | Mild (n = 256) | Moderate (n = 432) | Severe (n = 95) |
Respiratory symptoms | Crude model | Reference | 2.09 (1.37, 3.21) | 1.52 (0.83, 2.81) | 1.67 (1.03, 2.71) | 8.38 (4.16, 16.88) |
| Adjusted model* | Reference | 1.68 (1.05, 2.68) | 0.96 (0.49, 1.90) | 1.29 (0.77, 2.16) | 5.82 (2.80, 12.10) |
Cough | Crude model | Reference | 2.30 (1.27, 4.17) | 2.45 (1.08, 5.56) | 1.74 (0.87, 3.46) | 4.99 (2.04, 12.28) |
| Adjusted model* | Reference | 1.92 (0.99, 3.69) | 1.69 (0.65, 4.43) | 1.48 (0.71, 3.07) | 3.81 (1.44, 10.09) |
Sputum | Crude model | Reference | 2.13 (1.34, 3.39) | 1.71 (0.91, 3.22) | 1.69 (1.01, 2.84) | 6.84 (3.24, 14.44) |
| Adjusted model* | Reference | 1.72 (1.04, 2.86) | 1.26 (0.62, 2.56) | 1.27 (0.72, 2.23) | 4.53 (1.98, 10.38) |
Dyspnea | Crude model | Reference | 4.05 (1.30, 12.62) | 1.95 (0.43, 8.88) | 2.12 (0.56, 7.98) | 21.58 (5.51, 84.46) |
| Adjusted model* | Reference | 4.41 (1.40, 13.96) | 1.96 (0.44, 8.69) | 2.03 (0.53, 7.78) | 19.02 (4.06, 89.07) |
Physical activity limitations | Crude model | Reference | 7.20 (2.93, 17.66) | 3.55 (0.81, 15.46) | 3.60 (1.25, 10.38) | 38.35 (10.80, 136.15) |
| Adjusted model* | Reference | 8.13 (2.95, 22.41) | 3.00 (0.74, 12.11) | 4.13 (0.97, 17.64) | 92.20 (16.33, 520.62) |
EQ-5D index | Crude model | Reference | − 0.021 (− 0.036, − 0.069) | -0.006 (-0.261, 0.125) | − 0.020 (-0.038, -0.001) | − 0.066 (-0.108, -0.024) |
| Adjusted model* | Reference | − 0.001 (− 0.015, 0.014) | 0.015 (-0.005, 0.035) | -0.002 (-0.020, 0.015) | -0.055 (-0.096, -0.013) |
Data are presented as a ratio (95% confidence interval) or a difference estimate (95% confidence interval).
*Age, sex, education (categorized as > high school or ≤ high school), and family income (categorized as low or high) were adjusted.
EQ-5D, EuroQoL five dimensions; TB, tuberculosis.
In the analyses according to severity of obstructive ventilatory disorders, mild and moderate obstructive ventilatory disorders were not associated with more respiratory symptoms, more physical activity limitations, and lower EQ-5D index values in the unadjusted and adjusted models. However, severe obstructive ventilatory disorder was significantly associated with more respiratory symptoms (aOR = 5.82, 95% CI = 2.80–12.10), more physical activity limitations (aOR = 92.20, 95% CI = 16.33–520.62), and lower EQ-5D index value (adjusted coefficient = -0.055, 95% CI = -0.096 – -0.013) (Table 3).
The impact of restrictive ventilatory disorder and its severity on respiratory symptoms, physical activity limitations, and EQ-5D index value in post-TB subjects
Restrictive ventilatory disorder was not significantly associated with increased respiratory symptoms (cough, sputum, or dyspnea), physical activity limitations, and EQ-5D index value compared with normal ventilation in adjusted models (Table 4).
Table 4
The impact of severity of restrictive ventilatory disorder on EQ-5D index value in post-TB subjects
| Model | Normal (n = 1,466) | Restrictive ventilatory disorder | |
Overall ( n = 420) | Mild (n = 306) | Moderate (n = 77) | Severe (n = 37) |
Respiratory symptoms | Crude model | Reference | 1.61 (0.95, 2.72) | 1.95 (1.09, 3.49) | 0.95 (0.30, 3.06) | 0.59 (0.11, 3.24) |
| Adjusted model* | Reference | 1.59 (0.92, 2.77) | 1.95 (1.07, 3.56) | 0.98 (0.29, 3.36) | 0.56 (0.09, 3.31) |
Cough | Crude model | Reference | 0.95 (0.43, 4.17) | 0.96 (0.39, 2.38) | 0.77 (0.16, 3.80) | 1.11 (0.14, 8.98) |
| Adjusted model* | Reference | 0.94 (0.41, 2.13) | 0.95 (0.39, 2.32) | 0.78 (0.14, 4.32) | 1.06 (0.12, 9.35) |
Sputum | Crude model | Reference | 1.70 (0.93, 3.12) | 2.23 (1.16, 4.26) | 0.42 (0.09, 2.00) | 0.61 (0.08, 4.77) |
| Adjusted model* | Reference | 1.71 (0.91, 3.23) | 2.28 (1.17, 4.49) | 0.45 (0.09, 2.31) | 0.54 (0.06, 4.91) |
Dyspnea | Crude model | Reference | 2.49 (0.63, 9.81) | 1.20 (0.21, 6.82) | 8.56 (1.43, 51.34) | 1.94 (0.20, 18.40) |
| Adjusted model* | Reference | 2.27 (0.56, 9.27) | 0.80 (0.11, 5.91) | 13.52 (2.45, 74.82) | 2.83 (0.24, 33.47) |
Physical activity limitation | Crude model | Reference | 2.98 (0.76, 9.45) | 2.29 (0.46, 11.38) | 3.58 (0.71, 18.02) | 5.34 (0.85, 33.71) |
| Adjusted model* | Reference | 3.12 (0.83, 11.63) | 1.92 (0.20, 18.54) | 5.71 (1.14, 28.62) | 9.17 (1.02, 82.22) |
EQ-5D index | Crude model | Reference | − 0.029 (− 0.052, − 0.063) | -0.013 (-0.032, 0.007) | -0.088 (-0.170, -0.006) | -0.046 (-0.091, -0.001) |
| Adjusted model* | Reference | − 0.017 (− 0.038, 0.005) | -0.001 (-0.018, 0.017) | -0.026 (-0.149, 0.018) | -0.025 (-0.072, 0.022) |
Data are presented as a ratio (95% confidence interval) or a difference estimate (95% confidence interval).
*Adjusted for age, sex, BMI, education (categorized as > high school or ≤ high school), and family income (categorized as low or high).
EQ-5D, EuroQoL five dimensions; TB, tuberculosis.
In the analyses according to severity of restrictive ventilatory disorder, subjects with mild restrictive ventilatory disorders were more likely to have any respiratory symptoms (aOR = 1.95, 95% CI = 1.07–3.56) compared to those with normal ventilation, and these findings were specifically significant for sputum (aOR = 2.28, 95% CI = 1.17–4.49). In comparison, moderate (aOR = 9.17, 95% CI = 1.02–82.22) and severe (aOR = 9.17, 95% CI = 1.02–82.22) restrictive ventilatory disorders were associated with more physical activity limitations compared to those with normal ventilation (Table 4).