Table 2.
Results of subgroup analysis
| Outcome | Subgroup | Relative risk (95% confidence interval) and rank probabilities | |||||
|---|---|---|---|---|---|---|---|
| Tobramycin vs control; tobramycin (rank probability) | Colistin vs control; colistin (rank probability) | Amikacin vs control; amikacin (rank probability) | Tobramycin vs colistin | Tobramycin vs amikacin | Colistin vs amikacin | ||
| Clinical recovery | Geography | ||||||
| USA | 2.37 (1.7–5.62); tobramycin 97.3% | 1.3 (0.68–2.7); colistin 2.2% | 0.68 (0.27–1.7); amikacin 0.2% | 1.83 (1.2–4.67) | 3.4 (2.2–8.89) | 2 (0.65–6.3) | |
| Europe | 1.52 (0.52–6.6); tobramycin 65.4% | 1.2 (0.86–1.5); colistin 28.7% | 0.98 (0.67–1.5); amikacin 4.6% | 1.3 (0.42–5.7) | 1.6 (0.5–7.1) | 1.3 (0.72–1.9) | |
| Asia | 1.6 (0.74–3.3); tobramycin 82.3% | 0.95 (0.48–1.9); colistin 5.6% | – | 1.6 (0.60–4.5) | – | – | |
| Type of inhaled drug delivery system | |||||||
| Jet nebulizer | 2.1 (1.5–5.34); tobramycin 98.6% | 1.1 (0.71–1.8); colistin 1.2% | – | 2.53 (1.2–6.7) | – | – | |
| Ultrasonic nebulizer | 1.5 (0.85–3); tobramycin 78.8% | 1.2 (0.95–1.6); colistin 20.5% | – | 1.3 (0.67–2.6) | – | – | |
| Vibrating nebulizer | – | 1.3 (0.93–2); colistin 91.9% | 0.95 (0.72–1.2); amikacin 4.2% | – | – | 1.4 (0.91–2.3) | |
| VAP with or without MDR | |||||||
| VAP with MDR | – | 1.2 (0.70–1.7); colistin 66.4% | 0.97 (0.40–2.5); amikacin 24.8% | – | – | 1.2 (0.40–3.1) | |
| VAP without MDR | 1.7 (1.1–3.2); tobramycin 88.5% | 1.2 (0.83–1.7); colistin 9% | 0.68 (0.27–1.6); amikacin 2.1% | 1.5 (0.8–2.9) | 2.6 (0.94–7.8) | 1.8 (0.68–4.8) | |
| Type of studies | |||||||
| Randomized controlled trials | 2.2 (0.95–8); tobramycin 92.9% | 1.1 (0.71–1.8); colistin 5.6% | 0.94 (0.65–1.3); amikacin 0.8% | 2.5 (0.93–9.9) | 2.4 (0.96–8.7) | 1.2 (0.69–2.1) | |
| High risk of bias | 2.2 (0.91–7.7); tobramycin 87.5% | 0.94 (0.43–2); colistin 5.6% | 0.98 (0.47–2.1); amikacin 5.7% | 2.4 (0.74–10) | 2.3 (0.73–9.5) | 0.96 (0.33–2.8) | |
| Low risk of bias | – | 1.4 (0.73–2.8); colistin 82.1% | 0.92 (0.59–1.3); amikacin 7.7% | – | – | 1.5 (0.72–3.5) | |
| Observational studies | 1.6 (0.78–3.3); tobramycin 75.9% | 1.2 (0.88–1.6); colistin 22.9% | – | 1.3 (0.63–2.9) | – | – | |
| NOS = 9 | 1.6 (0.48–5.1); tobramycin 70.8% | 0.96 (0.51–1.81); colistin 23.7% | – | 1.3 (0.40–5.5) | – | – | |
| NOS < 9 | – | 1.2 (0.84–1.9); colistin 87.6% | – | – | – | – | |
| Administration strategy | |||||||
| Adjunctive strategy | 1.6 (0.94–2.70); tobramycin 81.4% | 1.2 (1.0–1.4); colistin 16.8% | 0.93 (0.64–1.3); amikacin 1.4% | 1.3 (0.76–2.3) | 1.7 (0.92–3.2) | 1.3 (0.87–2) | |
| Substitution strategy | 1.57 (0.46–5.34); tobramycin 98.9% | – | 0.96 (0.76–1.21); amikacin 0.7% | – | 1.64 (0.47–5.69) | – | |
| Mortality | Geography | ||||||
| USA | – | 1.4 (0.76–2.6); colistin 3.6% | 0.66 (0.30–1.4); amikacin 83.9% | – | – | 2.1 (0.79–5.8) | |
| Europe | 0.31 (0.039–1.6); tobramycin 85.7% | 1.2 (0.40–4.1); colistin 0.1% | 0.87 (0.57–1.3); amikacin 7.8% | 0.36 (0.044–5.0) | 0.25 (0.022–1.8) | 0.72 (0.20–2.3) | |
| Asia | 0.33 (0.074–1.4); tobramycin 86.9% | 0.92 (0.26–3.3); colistin 10.6% | – | 0.36 (0.051–2.4) | – | – | |
| Type of inhaled drug delivery system | |||||||
| Jet nebulizer | – | 0.88 (0.63–1.2); colistin 81.6% | – | – | – | – | |
| Ultrasonic nebulizer | 0.33 (0.11–0.87); tobramycin 97.2% | 0.92 (0.64–1.4); colistin 1.7% | – | 0.36 (0.11–1.0) | – | – | |
| Vibrating nebulizer | – | 1.3 (0.70–2.4); colistin 20% | 1.3 (0.68–2.6); amikacin 14.8% | – | – | 1.0 (0.40–2.4) | |
| VAP with or without MDR | |||||||
| VAP with MDR | – | 0.81 (0.55–1.2); colistin 70.9% | 1.3 (0.39–6.3); amikacin 22.3% | – | – | 0.61 (0.12–2.1) | |
| VAP without MDR | 0.34 (0.13–0.78); tobramycin 71.7% | 0.91 (0.54–1.5); colistin 7.4% | 0.7 (0.3–1.7); amikacin 26.7% | 0.37 (0.12–1) | 0.48 (0.13–1.6) | 1.3 (0.47–3.5) | |
| Type of studies | |||||||
| Randomized controlled trials | 0.31 (0.039–1.6); tobramycin 80.9% | 0.95 (0.45–2); colistin 6.6% | 0.83 (0.41–1.8); amikacin 11.3% | 0.32 (0.036–2) | 1.1 (0.38–3.1) | 0.37 (0.042–2.3) | |
| High risk of bias | 0.31 (0.039–1.8); tobramycin 73.5% | 0.92 (0.32–2.7); colistin 8% | 1.1 (0.11–10); amikacin 16.3% | 0.33 (0.033–2.7) | 0.28 (0.013–5.2) | 0.86 (0.073–10) | |
| Low risk of bias | – | 0.81 (0.43–1.6); colistin 31.4% | 1 (0.25–3.9); amikacin 50.3% | – | – | 1.2 (0.27–5.5) | |
| Observational studies | 0.34 (0.11–0.9); tobramycin 95.7% | 0.83 (0.58–1.1); colistin 3.9% | – | 0.41 (0.12–1.2) | – | – | |
| NOS = 9 | 0.34 (0.094–0.96); tobramycin 95.1% | 0.86 (0.54–1.3); colistin 4.2% | – | 0.39 (0.1–1.2) | – | – | |
| NOS < 9 | – | 0.67 (0.35–1.3); colistin 90.2% | – | – | – | – | |
| Administration strategy | |||||||
| Adjunctive strategy | 0.34 (0.14–0.72); tobramycin 95% | 0.85 (0.66–1.1); colistin 0.83% | 0.8 (0.44–1.5); amikacin 4.1% | 0.4 (0.16–0.88) | 0.42 (0.14–1.1) | 1.1 (0.54–2) | |
| Substitution strategy | – | – | 0.99 (0.088–9.5); amikacin 48.7% | – | – | – | |
MDR multidrug resistance, NOS Newcastle-Ottawa scale, VAP ventilator-associated pneumonia