Table 6.

Generalized linear model for exacerbation-related costs (log link and Gamma distribution)^a

Analysis of maximum likelihood parameter estimates
Parameter	Estimate	Exponentiated estimate	Standard error	Wald 95% confidence limits	P-value
Age in years (<65 as reference)
65–<70	−0.84	0.43	0.36	−1.55, −0.14	0.019
70–<75	0.21	1.23	0.39	−0.55, 0.97	0.594
75–<80	−0.65	0.52	0.40	−1.44, 0.13	0.104
80+	−0.37	0.69	0.40	−1.16, 0.42	0.362
Sex (Male as reference)	−0.52	0.60	0.23	−0.97, −0.06	0.026
Race (white as reference)
Black	−0.65	0.52	0.52	−1.67, 0.37	0.214
Hispanic	−4.98	0.01	1.11	−7.16, −2.80	<0.001
Other	1.32	3.75	0.94	−0.51, 3.16	0.158
Region (South as reference)
Northeast	−2.49	0.08	0.78	−4.02, −0.97	0.001
Midwest	0.88	2.42	0.28	0.33, 1.44	0.002
West	0.58	1.78	0.41	−0.23, 1.39	0.161
Dual eligibility only	0.29	1.34	0.49	−0.66, 1.25	0.550
LIS status only	−0.40	0.67	0.39	−1.15, 0.36	0.304
RxRisk-V comorbidity index score	0.06	1.06	0.03	−0.01, 0.13	0.075
Deyo–Charlson comorbidity index score	0.20	1.23	0.06	0.08, 0.33	0.002
Number of pre-index exacerbations	0.55	1.73	0.13	0.30, 0.80	<0.001
Symptoms by CATb (low as reference)	1.42	4.14	0.27	0.89, 1.95	<0.001
Symptoms by mMRCc (low as reference)	0.22	1.24	0.24	−0.25, 0.68	0.358

Notes:

^aThe scale parameter was estimated by the maximum likelihood method;

^blow symptom: CAT score <10; high symptom: CAT score ≥10;

^clow symptom: mMRC score <2; high symptom: mMRC score ≥2.

Abbreviations: CAT, COPD assessment test; mMRC, modified Medical Research Council; LIS, low income subsidy.