Table 3

Comparison of pseudo R2* for sequential models† incorporating explanatory variables for the trend in ED practice intensity

ModelExplanatory variablesAll visitsInpatient visitsOutpatient visits
1Time0.0130.0340.027
2Time, patient characteristics‡0.0210.0340.028
3Time, patient characteristics, comorbidities§0.0900.0360.043
4Time, patient characteristics, comorbidities, services¶0.1480.0510.465
  • *Pseudo R2 determined using method described by Cragg and Uhler.26

  • †Generalised logistic regression modelling was used to account for clustering at the level of the ED.

  • ‡Patient demographics included age, race, gender and Medicaid eligibility.

  • §Comorbidities were characterised by the mean number of HCCs.

  • ¶Services refers to ICD-9 procedures for inpatient visits, HCPCS procedures for outpatient visits and physician-billed HCPCS procedures in the carrier file for all visits.

  • ED, emergency department; HCC, Hierarchical Condition Category; HCPCS, Healthcare Common Procedure Coding System; ICD-9, International Classification of Diseases, Ninth Revision.