Table 3.
Choice models allowing for patient pre-operative Oxford Hip Score.
| Variable | Patients with pre-op OHS (1) | Patients with pre-op OHS (2) | All patients (3) | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Responders (3a) | Non-responders (3b) | Difference (3c) | ||||||||
| Est | SE | Est | SE | Est | SE | Est | SE | Est | SE | |
| Main effects | ||||||||||
| Change in Oxford Hip Score | 0.153 | 0.009*** | 0.141 | 0.009*** | 0.139 | 0.009*** | 0.113 | 0.009*** | 0.026 | 0.009** |
| 28-day emergency readmission rate (%) | −0.058 | 0.005*** | −0.051 | 0.005*** | −0.051 | 0.005*** | −0.048 | 0.006*** | −0.003 | 0.005 |
| 1-year revision rate (%) | −0.028 | 0.011* | −0.002 | 0.011 | −0.003 | 0.011 | −0.036 | 0.014** | 0.032 | 0.013* |
| 28-day mortality rate (%) | −0.137 | 0.033*** | −0.052 | 0.030 | −0.052 | 0.030 | −0.021 | 0.034 | −0.031 | 0.033 |
| Distance (in km) | −0.265 | 0.008*** | −0.264 | 0.008*** | −0.265 | 0.009*** | −0.281 | 0.006*** | 0.017 | 0.008* |
| Distance2 | 0.002 | 0.000*** | 0.002 | 0.000*** | 0.002 | 0.000*** | 0.003 | 0.000*** | 0.000 | 0.000 |
| Distance3 | −0.00001 | 0.000*** | 0.000 | 0.000*** | 0.000 | 0.000*** | 0.000 | 0.000*** | 0.000 | 0.000 |
| NHS trust – medium | −0.517 | 0.035*** | −0.591 | 0.034*** | −0.583 | 0.034*** | −0.565 | 0.036*** | −0.018 | 0.031 |
| NHS trust – multi-service | −0.948 | 0.125*** | −0.961 | 0.124*** | −0.951 | 0.123*** | −0.625 | 0.107*** | −0.325 | 0.126** |
| NHS trust – small | −0.799 | 0.043*** | −0.854 | 0.043*** | −0.849 | 0.042*** | −0.885 | 0.046*** | 0.036 | 0.039 |
| NHS trust – specialist | 1.184 | 0.074*** | 0.961 | 0.076*** | 0.954 | 0.076*** | 0.979 | 0.100*** | −0.025 | 0.068 |
| NHS trust – teaching | −0.383 | 0.037*** | −0.425 | 0.037*** | −0.414 | 0.037*** | −0.539 | 0.039*** | 0.125 | 0.034*** |
| Independent sector treatment centre | −1.520 | 0.043*** | −1.548 | 0.042*** | −1.556 | 0.042*** | −1.698 | 0.046*** | 0.141 | 0.042*** |
| Primary care trust | −1.031 | 0.219*** | −1.404 | 0.221*** | −1.400 | 0.221*** | −1.263 | 0.254*** | −0.137 | 0.251 |
| Waiting time (proportion waiting >120 days) | −0.343 | 0.088*** | −0.026 | 0.086 | −0.024 | 0.085 | −0.399 | 0.092*** | 0.375 | 0.088*** |
| Response rate (%) | 0.019 | 0.001*** | 0.019 | 0.001*** | −0.027 | 0.001*** | 0.046 | 0.001*** | ||
| Interaction with pre-operative Oxford Hip Score | ||||||||||
| × Change in Oxford Hip Score | 0.000 | 0.000 | 0.000 | 0.000 | ||||||
| × 28-day emergency readmission rate (%) | 0.000 | 0.000 | 0.000 | 0.000 | ||||||
| × 1-year revision rate (%) | 0.000 | 0.001 | 0.001 | 0.001 | ||||||
| × 28-day mortality rate (%) | 0.002 | 0.002 | 0.003 | 0.002 | ||||||
| × Distance (in km) | 0.001 | 0.000*** | 0.001 | 0.000*** | ||||||
| × Distance2 | 0.000 | 0.000** | 0.000 | 0.000** | ||||||
| × Distance3 | 0.000 | 0.000** | 0.000 | 0.000** | ||||||
| × NHS trust – medium | −0.002 | 0.002 | −0.004 | 0.002* | ||||||
| × NHS trust – multi-service | −0.007 | 0.007 | −0.008 | 0.007 | ||||||
| × NHS trust – small | −0.002 | 0.002 | −0.003 | 0.002 | ||||||
| × NHS trust – specialist | 0.014 | 0.003*** | 0.011 | 0.003*** | ||||||
| × NHS trust – teaching | −0.007 | 0.002*** | −0.008 | 0.002*** | ||||||
| × Independent sector treatment centre | 0.029 | 0.002*** | 0.027 | 0.002*** | ||||||
| × Primary care trust | 0.000 | 0.008 | −0.004 | 0.008 | ||||||
| × Waiting time (proportion waiting >120 days) | −0.001 | 0.005 | 0.002 | 0.005 | ||||||
| × Response rate (%) | 0.000 | 0.000*** | ||||||||
| WTT (OHS change) | 1.075 | 0.062*** | 0.991 | 0.064*** | 0.974 | 0.063*** | 0.756 | 0.064*** | 0.218 | 0.062*** |
| WTT (Readmission rate) | −0.689 | 0.057*** | −0.612 | 0.056*** | −0.604 | 0.056*** | −0.544 | 0.063*** | −0.060 | 0.060 |
| WTT (Revision rate) | −0.116 | 0.046* | −0.006 | 0.045 | −0.013 | 0.045 | −0.139 | 0.053** | 0.126 | 0.051* |
| WTT (Mortality rate) | −0.243 | 0.060*** | −0.092 | 0.054 | −0.093 | 0.054 | −0.036 | 0.058 | −0.057 | 0.057 |
| Number of patients | 113,846 | 113,846 | 170,916 | |||||||
| Number of providers | 228 | 228 | 228 | |||||||
| BIC | 296,526 | 292,634 | 432,899 | |||||||
| Pseudo R2 | 0.658 | 0.662 | 0.667 | |||||||
Notes: Conditional logit model of choice of hospital for elective hip replacement patients treated between April 2010 and March 2012. Waiting time and quality metrics are lagged by one year. Coefficients are marginal utilities. WTT is the ratio of the coefficient on the quality variable to the marginal utility of distance evaluated at the average distance to the chosen provider. Models in (1) and (2) are for patients reporting a pre-operation OHS. Model in (3) is for all patients and interacts a dummy variable for reporting a pre-operation OHS. Interaction effects are reported in (3c). All models also contain a full set of interactions of age, gender, past utilisation, Elixhauser comorbidities, and deprivation with hospital characteristics and distance (not reported). Standard errors are clustered at GP practice level.
p < 0.001;
p < 0.01;
p < 0.05.