Fixed Effect Meta-Analysis Results of Selected Spirometry Variables. Graphs displayed are: A) FEV1 % Predicted (COPD Exacerbation Severity Levels I to III); B) FEV1 % Predicted (Out- versus In-patient Setting); C) FVC % Predicted (Levels I to III); and D) FVC % Predicted (Out- versus In-patient Setting). For each spirometry variable, the point estimates (point), 95% confidence intervals (box), and two standard deviations (bars) are presented for Levels I to III and out- & in-patient settings. 'N' signifies the total studies and 'n' is the total subjects. P < 0.017 is indicated for statistical comparisons of Level I versus II (*), II versus III (†), and I versus III (#) as well as P < 0.05 for comparison of out- versus in-patient setting (*).