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Table 4 Negative binomial regression model for factors associated with frequency of emergency department visits for acute exacerbation of chronic obstructive pulmonary disease

From: Frequent utilization of the emergency department for acute exacerbation of chronic obstructive pulmonary disease

Variables Risk ratio (95% CI) P value
Age, y   
 40-54 years 1 [reference]  
 55-64 years 1.07 (1.06-1.09) <0.001
 65-74 years 1.02 (1.00-1.03) 0.04
 75-84 years 0.94 (0.92-0.96) <0.001
 85 years and older 0.86 (0.85-0.88) <0.001
Male sex   
Race/ethnicity   
 Non-hispanic white 1.08 (1.06-1.09) <0.001
 Non-hispanic black 1.15 (1.13-1.17) <0.001
 Hispanic 1 [reference]  
 Other 1.01 (0.98-1.03) 0.62
Insurance status   
 Medicare 1.21 (1.19-1.23) <0.001
 Medicaid 1.34 (1.32-1.36) <0.001
 Private 1 [reference]  
 Self-pay 1.01 (0.99-1.03) 0.45
 Other 1.13 (1.10-1.16) <0.001
Quartiles for median household income of patient’s ZIP code
 1 (lowest) 1.06 (1.05-1.08) <0.001
 2 1.05 (1.03-1.06) <0.001
 3 1.03 (1.01-1.04) <0.001
 4 (highest) 1 [reference]  
Patient residence   
 Counties of ≥ 1 million population 1.03 (1.01-1.05) <0.001
 Counties of 250,000-999,999 population 1.04 (1.02-1.05) <0.001
 Counties of 50,000-249,999 population 1.03 (1.01-1.06) 0.007
 Counties of < 50,000 population 1 [reference]  
State   
 California 1.02 (1.02-1.03) <0.001
 Florida 1 [reference]  
Selected comorbidities   
 Congestive heart failure 1.05 (1.04-1.06) <0.001
 Pulmonary circulation disorders 1.13 (1.09-1.17) <0.001
 Diabetes, uncomplicated 1.04 (1.03-1.05) <0.001
 Obesity 0.97 (0.96-0.99) <0.001
 Depression 1.08 (1.07-1.10) <0.001
 Psychoses 1.08 (1.06-1.10) <0.001
 Drug abuse 1.18 (1.15-1.21) <0.001
  1. Abbreviations: COPD chronic obstructive pulmonary disease, ED emergency department CI confidence interval.
  2. Bold results are statistically significant.