Table 2.
Random effect negative binomial regression on ER visits
| IRR | SE | p | 95% CI | |
|---|---|---|---|---|
| Race/ethnicity |
|
|
|
|
| Non-Latino Whitea |
|
|
|
|
| Black |
0.852 |
0.031 |
< .001 |
0.793, 0.915 |
| Latino |
0.826 |
0.025 |
< .001 |
0.778, 0.876 |
| Age |
1.000 |
0.001 |
.836 |
0.997, 1.002 |
| Male |
0.777 |
0.021 |
< .001 |
0.737, 0.819 |
| Education |
1.017 |
0.005 |
.001 |
1.007, 1.028 |
| Homeless |
1.212 |
0.035 |
< .001 |
1.145, 1.283 |
| History of mental health issues |
0.661 |
0.018 |
< .001 |
0.627, 0.698 |
| Days of mental health counseling |
1.021 |
0.003 |
< .001 |
1.015, 1.028 |
| Days of psychiatric care |
1.032 |
0.003 |
< .001 |
1.025, 1.039 |
| Days of physical problems |
1.067 |
0.001 |
< .001 |
1.065, 1.069 |
| Age at first drug use |
0.998 |
0.002 |
.210 |
0.995, 1.001 |
| Days of primary drug use |
0.996 |
0.001 |
.001 |
0.994, 0.998 |
| Primary drug problem |
|
|
|
|
| Alcohola |
|
|
|
|
| Cocaine |
1.790 |
0.075 |
< .001 |
1.649, 1.942 |
| Heroin |
1.113 |
0.051 |
.020 |
1.017, 1.218 |
| Marijuana |
1.194 |
0.059 |
< .001 |
1.083, 1.316 |
| Methamphetamine |
1.113 |
0.072 |
.096 |
0.981, 1.264 |
| Other |
1.620 |
0.090 |
< .001 |
1.454, 1.806 |
| Children younger than 18 |
1.008 |
0.004 |
.036 |
1.001, 1.016 |
| Program modality |
|
|
|
|
| Outpatienta |
|
|
|
|
| Methadone |
0.964 |
0.116 |
.763 |
0.761, 1.221 |
| Residential | 1.606 | 0.068 | < .001 | 1.479, 1.744 |
Note: ER, emergency room; IRR, incidence rate ratio. IRRs can be interpreted as the estimated rate ratio for a 1-unit increase in the independent variable, given the other variables are held constant in the model. For example, if days of physical problems increased by 1 point, the ratio for number of ER visits would be expected to increase by a factor of IRR = 1.067, while holding all other variables in the model constant.
Wald chi-square tests with degrees of freedom (20) = 6693.30. The corresponding p-value is less than 0.0001.
aReference category.