Table 3. Association between publication characteristics and methodological quality of MAs on COPD treatments: multivariate analyses.

AMSTAR item (dependent variable)	Predictors	Adjusted odds ratio (99% CI)	P values
1. Was an 'a priori' design provided? (Yes versus No)	Higher impact factor	4.22 (1.50–11.86)	<0.0001
2. Was there duplicate study selection and data extraction? (Yes versus Cannot answer)	Higher impact factor	2.01 (1.19–3.38)	0.001
5. Was a list of studies provided? (Yes versus No)	Higher impact factor	6.85 (1.58–29.69)	0.001
7. Was the scientific quality of the included studies assessed and documented? (Yes versus No)	More recent publication years	1.40 (0.94–2.08)	0.030
8. Was the scientific quality of the included studies used appropriately in formulating conclusions? (Yes versus No)	Non-pharmacological treatment (pharmacological treatment as reference)	6.53 (0.92–46.36)	0.014
9. Were the methods used to combine the findings of studies appropriate? (Yes versus No)	Non-pharmacological treatment (pharmacological treatment as reference)	4.49 (0.98–20.72)	0.011
10. Was the likelihood of publication bias assessed? (Yes versus No)	More recent publication years	1.83 (1.13–2.97)	0.001

Abbreviations: AMSTAR, Assessing the Methodological Quality of Systematic Reviews; CI, confidence interval; COPD, chronic obstructive pulmonary disease; MA, meta-analysis.