Use of prolonged travel to improve pediatric risk-adjustment models

Abstract

Objective: To determine whether travel variables could explain previously reported differences in lengths of stay (LOS), readmission, or death at children's hospitals versus other hospital types.

Data source: Hospital discharge data from Pennsylvania between 1996 and 1998.

Study design: A population cohort of children aged 1-17 years with one of 19 common pediatric conditions was created (N=51,855). Regression models were constructed to determine difference for LOS, readmission, or death between children's hospitals and other types of hospitals after including five types of additional illness severity variables to a traditional risk-adjustment model.

Principal findings: With the traditional risk-adjustment model, children traveling longer to children's or rural hospitals had longer adjusted LOS and higher readmission rates. Inclusion of either a geocoded travel time variable or a nongeocoded travel distance variable provided the largest reduction in adjusted LOS, adjusted readmission rates, and adjusted mortality rates for children's hospitals and rural hospitals compared with other types of hospitals.

Conclusions: Adding a travel variable to traditional severity adjustment models may improve the assessment of an individual hospital's pediatric care by reducing systematic differences between different types of hospitals.

Figure1

Adjusted Coefficients for Different Hospital Types Compared with Urban Nonteaching Hospitals for LOS (A), Readmissions (B), and Mortality (C) Note: Each symbol represents the coefficient for each type of hospital, with the bars showing 95 percent confidence intervals, after adjusting for age, sex, gender, admission condition, presence of comorbid conditions, source of admission, insurance status, and significant interaction terms. After the coefficients for the base model (solid circle) are presented, the following models are shown from left to right, as indicated by the numbers above the models: distance models (solid diamond and square), #1; MedisGroups models (solid square, small circle, small diamond), #2; travel time models (small square and hollow circle for travel time, small triangle and hollow diamond for excess travel time), #3; and hospital-specific market models (hollow triangle and square), #4. Coefficients statistically significant from the base risk-adjustment model are indicated with a star, while coefficients statistically significant from the 15-minute travel time model are indicated with a plus.