Figure 1.
Age, gender and seasonal distribution of COPD hospitalizations.
The left panel displays the age distribution stratified by gender of patients with COPD diagnosis. The right panels show the seasonal effect in the hospitalization of acute COPD patients (COPD as main diagnosis), over the 2002–2010 period (upper right panel), and further summarized over monthly fluctuations (lower right panel).
Table 1.
Characteristics of patients with COPD compared to age- and sex-matched patients without diagnosis of COPD (controls).
Table 2.
Prevalence (in percentage) of the most significantly over−/under-represented comorbidities in patients with COPD compared to age- and sex- matched patients without diagnosis of COPD.
Figure 2.
Principal component analysis biplot of comorbidities associated with COPD.
Hospitalization cases (PCA scores) are represented on the first 2 principal component axes using smoothed blue colored density. Comorbidities coded according to ICD-10 are depicted by framed labels (PCA loadings). Comorbidities lying in the same directions are correlated with each other. The further away from the center of the plot, the stronger is the influence of comorbidities. External explanatory variables (including age, gender, length-of-hospital stay [LOS], in-hospital death [Death], hospitalization rate, number of comorbidities and Charlson’s comorbidity score) were fitted to the PCA and displayed in the upper right box using vectors representations (red arrows). The number displayed on the upper left corner indicates the size of the grid.
Figure 3.
Discrimination between emphysema, bronchitis and asthma-associated COPD patients based on comorbidities using between-group principal component analysis (axes 1–2).
Hospitalization cases are displayed in the first 2 axes of the between-group PCA (smoothed blue colored density). The ellipsoids summarize the dispersion of the 3 COPD subtypes in the factorial map. Comorbidities are coded according to ICD-10 codes and depicted by framed labels. The number displayed on the upper left corner indicates the size of the grid.
Table 3.
List of 10 comorbidities mostly associated with each of the 3 COPD subtypes (emphysema, bronchitis, asthma).