TABLE 3.
Multivariate Regression Results
| Parameter | Co-efficient | Standard Error | P Value |
|---|---|---|---|
| Intercept | 8.08 | 0.07 | < 0.001 |
| Patient characteristics | |||
| Age | 0.00 | 0.00 | 0.078 |
| Male | -0.15 | 0.03 | < 0.001 |
| U.S. Census Division: Unknown | 0.19 | 0.40 | 0.636 |
| U.S. Census Division 1: New England | -0.10 | 0.07 | 0.157 |
| U.S. Census Division 2: Middle Atlantic | -0.01 | 0.04 | 0.807 |
| U.S. Census Division 4: West North Central | 0.09 | 0.07 | 0.189 |
| U.S. Census Division 5: South Atlantic | 0.09 | 0.04 | 0.034 |
| U.S. Census Division 6: East South Central | -0.16 | 0.06 | 0.005 |
| U.S. Census Division 7: West South Central | 0.12 | 0.05 | 0.015 |
| U.S. Census Division 8: Mountain | 0.11 | 0.05 | 0.043 |
| U.S. Census Division 9: Pacific | 0.23 | 0.06 | < 0.001 |
| Year of index date: 2007 | -0.01 | 0.05 | 0.901 |
| Year of index date: 2008 | 0.07 | 0.05 | 0.159 |
| Year of index date: 2009 | 0.01 | 0.05 | 0.866 |
| Year of index date: 2010 | -0.03 | 0.05 | 0.468 |
| Year of index date: 2011 | -0.07 | 0.05 | 0.170 |
| Comorbidities | |||
| Components of Charlson Comorbidity Index | |||
| Chronic pulmonary disease | 0.14 | 0.05 | 0.011 |
| Mild-to-moderate diabetes | 0.16 | 0.07 | 0.014 |
| Rheumatologic disease | 0.25 | 0.09 | 0.008 |
| Congestive heart failure | 0.16 | 0.11 | 0.137 |
| Any malignancy including leukemia and lymphoma | 0.16 | 0.10 | 0.123 |
| Cerebrovascular disease | 0.18 | 0.11 | 0.092 |
| Diabetes with chronic complications | 0.34 | 0.12 | 0.004 |
| Peripheral vascular disease | 0.11 | 0.12 | 0.337 |
| Mild liver disease | 0.21 | 0.13 | 0.121 |
| Renal disease | 0.44 | 0.14 | 0.002 |
| Peptic ulcer disease | 0.15 | 0.18 | 0.393 |
| Myocardial infarction | 0.10 | 0.21 | 0.640 |
| Hemiplegia or paraplegia | 0.59 | 0.21 | 0.005 |
| Metastatic solid tumor | 0.63 | 0.24 | 0.008 |
| HIV/AIDS | 0.46 | 0.24 | 0.061 |
| Moderate or severe liver disease | 0.85 | 0.35 | 0.015 |
| Dementia | -0.17 | 0.73 | 0.815 |
| Other selected comorbidities | |||
| Nonopioid substance abuse diagnoses | 0.01 | 0.05 | 0.814 |
| Psychotic disorders | 0.07 | 0.04 | 0.092 |
| Other mental disorders | 0.00 | 0.03 | 0.898 |
| Baseline health care costs (log-transformed) | |||
| Medical costs | 0.09 | 0.01 | < 0.001 |
| Prescription drug costs | 0.10 | 0.10 | < 0.001 |
| Baseline health care resource use (number of visits/days) | |||
| Inpatient days | 0.01 | 0.00 | < 0.001 |
| Emergency department days | 0.02 | 0.00 | < 0.001 |
| Outpatient visits | 0.01 | 0.00 | < 0.001 |
| Drug/alcohol rehabilitation facility days | 0.01 | 0.00 | 0.050 |
| Other visits | 0.01 | 0.00 | 0.014 |
Note: An ordinary least squares (OLS) regression was performed on log-transformed health care costs. N = 9,291; R-squared value = 0.273. Results were considered statistically significant at P < 0.05.
AIDS = acquired immune deficiency syndrome; HIV = human immunodeficiency virus.