Table 4.

—Prospective Association of Helplessness With COPD-Related Emergency Health-Care Use, Controlling for Sociodemographics, Smoking Status, and COPD Severity (BODE Index): Multivariable Analysis Stratified by COPD Severity

	Low COPD Severity (BODE ≤ Median)an = 738		High COPD Severity (BODE > Median)an = 464
	HR (95% CI)	P Value	HR (95% CI)	P Value
Age,b y	1.3 (1.1-1.6)	.001	1.0 (0.9-1.1)	.89
Female gender	0.8 (0.6-1.3)	.43	0.9 (0.6-1.2)	.46
Married or cohabiting	0.9 (0.6-1.3)	.48	0.7 (0.5-1.02)	.07
College graduate	0.5 (0.3-0.96)	.036	1.1 (0.7-1.6)	.72
White non-Latino	1.0 (0.7-1.6)	.89	0.8 (0.6-1.1)	.16
Tobacco status
Never smoker	1.0 [Reference]	N/A	1.0 [Reference]	N/A
Former smoker	1.8 (0.7-4.2)	.20	4.2 (1.8-9.6)	.001
Current smoker	2.9 (1.2-7.0)	.017	3.8 (1.6-8.9)	.002
BODE Indexc	2.35 (1.5-3.7)	< .001	1.87 (1.5-2.4)	< .001
CHIc	1.35 (1.1-1.7)	.010	0.93 (0.8-1.1)	.34

Multivariable Cox proportional hazards analysis included all covariates listed above. COPD-related emergency health-care use was our proxy for acute exacerbations of COPD and was defined as the combined end point of either a COPD-related hospitalization or an ED visit. P values < .05 are in boldface type. HR = hazard ratio; N/A = not applicable. See Tables 1 and 3 for expansion of other abbreviations.

^aBODE Index median = 3 on a possible scale of 0 to 10.

^bHR expressed per 5-y increment in age.

^cHRs are expressed per 1 standard deviation increment in CHI and BODE Index, both of which represent worse health status.