Table 3

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

ModelExplanatory variablesAll visitsInpatient visitsOutpatient visits
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.