Table 3.

Multivariate Analyses of Direct Costs (n=7 Studies)

Measure of Direct Costs	Independent Drivers (Positive)	Independent Drivers (Negative)
Costs per patient	MRC dyspnea scale score;27 receipt of appropriate pharmacotherapy with an inhaled bronchodilator (vs no receipt);51 older age (vs younger age);51 higher pre-index costs;51 longer length of stay at baseline admission;51 black or other race (vs white race);23 income (high vs not higha);23 cardiovascular disease (vs no cardiovascular disease);23 diabetes (vs no diabetes);23 ICS + LABA maintenance medication;23 LAMA maintenance medication;23 LABA maintenance medication;23 LTOT use;23 exacerbation severity;23 health plan type (vs preferred provider organization);29 Deyo-Charlson Comorbidity Index;29 prescription fills for SAMA rescue medications;29 exacerbation frequency29	Age;23 Northeast US geographical region (vs South);29 prescription fills for fixed-dose ICS + LABA rescue medication29
Costs per hospitalized exacerbationb	Hispanic race (vs white race);31 age;36 CCI;36 female gender (vs male);36 emphysema (vs chronic bronchitis);36 ICU treatment (vs no ICU treatment);36 intubation;36 East or West US geographical location (vs North);36 hospital size (medium or large vs small);36 congestive heart failure;32 ischemic heart disease;32 cardiac dysrhythmia;32 pulmonary vascular disease;32 pneumonia;32 intrathoracic malignancies;32 anemia;32 renal failure;32 weight loss/cachexia;32 anxiety and depression32	South US geographical location (vs North);36 transfer, routine or other admission (vs ED admission);36 Medicaid or Blue Cross/Blue Shield (vs Medicare);36 health maintenance organization or commercial cover (vs Medicare)36

Notes: ^aHigh income was defined as income ≥$52,480 (USD). ^bCOPD severity, length of hospital stay, number of days in the ICU and treatment in an urban hospital or teaching hospital were also identified as significant drivers of direct costs, but the direction of the association was not clearly reported.³¹

Abbreviations: CCI, Charlson Comorbidity Index; COPD, chronic obstructive pulmonary disease; ED, emergency department; ICS, inhaled corticosteroid; ICU, intensive care unit; LABA, long-acting β₂-agonist; LAMA, long-acting muscarinic antagonist; LTOT, long-term oxygen therapy; MRC, Medical Research Council; SAMA, short-acting muscarinic antagonist; US, United States; USD, United States dollars.