Table 4

Estimated Effects of Admission Time, Patient and Hospital Characteristics on Log Duration of Emergency Department Visits
Linear Regression Models Multilevel Model
    Model 1
    Model 2
    Model 3
    Model 4
Parameters Std. Errors Parameters Std. Errors Parameters Std. Errors Parameters Std. Errors
Admission Day 1
Visit was on Monday 0.045*** (0.002) 0.044*** (0.002) 0.045*** (0.002) 0.041*** (0.002)
Visit was on weekend −0.057*** (0.002) −0.059*** (0.002) −0.056*** (0.001) −0.055*** (0.001)
Patient Demographics Characteristics
Age 0.014*** (0.000) 0.015*** (0.000) 0.013*** (0.000) 0.013*** (0.000)
Age-squared 0.001*** (0.000) 0.001*** (0.000) 0.001*** (0.000) 0.001*** (0.000)
Female 0.049*** (0.002) 0.046*** (0.002) 0.035*** (0.001) 0.039*** (0.001)
White 0.077*** (0.004) −0.031*** (0.004) 0.146*** (0.003) 0.137*** (0.003)
Black 0.107*** (0.005) 0.007 (0.005) 0.179*** (0.003) 0.165*** (0.003)
Hispanic 0.115*** (0.004) 0.013*** (0.004) 0.131*** (0.003) 0.122*** (0.003)
Asian 0.267*** (0.007) 0.162*** (0.007) 0.231*** (0.005) 0.222*** (0.005)
Medicare 0.103*** (0.004) 0.108*** (0.004) 0.149*** (0.003) 0.152*** (0.003)
Medicaid −0.143*** (0.003) −0.141*** (0.003) 0.094*** (0.002) 0.096*** (0.002)
Private 0.089*** (0.003) 0.101*** (0.003) 0.116*** (0.002) 0.119*** (0.002)
Self-paid −0.149*** (0.004) −0.146*** (0.004) −0.037*** (0.003) −0.036*** (0.003)
Hospital Characteristics
Teaching hospitals 0.146*** (0.002) 0.144*** (0.002) . . 0.125 (0.282)
For-profit hospitals −0.596*** (0.002) −0.599*** (0.002) . . −0.318 (0.313)
Trauma Level 1 hospitals 0.418*** (0.003) 0.411*** (0.003) . . 0.557 (0.453)
Trauma Level 2 hospitals −0.968*** (0.004) −0.959*** (0.004) . . −0.352 (0.634)
Trauma Level 3 hospitals −0.731*** (0.004) −0.728*** (0.004) . . −0.693 (0.587)
Medium size hospitals2 −0.361*** (0.002) −0.354*** (0.002) . . −0.168 (0.308)
Large hospitals −0.119*** (0.002) −0.112*** (0.002) . . 0.041 (0.312)
Member hospitals −0.312*** (0.002) −0.307*** (0.002) . . −0.322 (0.263)
Urban hospitals 0.095*** (0.003) 0.091*** (0.003) . . 0.207 (0.320)
Control for CCS codes3 Yes Yes Yes Yes
Control for admission hour4 No Yes Yes No
Control for hospital5 No No Yes
Total number of visits 4,768,411 4,761,855 4,761,855 4,718,553
R-square 0.096 0.097 0.542
Inra-class correlation . . 0.565

Note: Data include all treat-and-release discharges at emergency departments during 2008 in Arizona, Massachusetts, and Utah. Duration is measured in minutes as the difference between admission and discharge time for each visit.

1 The control group was the average of non-Monday workdays.

2 Further details about hospital bed sizes are available at http://www.hcup-us.ahrq.gov/db/vars/hosp_bedsize/nisnote.jsp webcite.

3 Disease categories are based on Clinical Classification Software, which is a diagnosis and procedure categorization scheme based on the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM).The HCUP SEDD do not differentiate between the primary diagnosis codes and other diagnosis codes. Therefore, we used all diagnosis codes reported for each visit when creating broader CCS disease categories.

4 We created dummy variables for each hour of the day.

5 We created dummy variables for each hospital.

*** P<0.001; ** P<0.05; * P<0.10.

Karaca et al.

Karaca et al. BMC Emergency Medicine 2012 12:15   doi:10.1186/1471-227X-12-15

Open Data