Primary and secondary outcome measures at intervention sites compared with control sites during study period
| Measure | IRR/coefficient estimate (β) | 95% CI | P value |
| Routine laboratory tests (IRR) | |||
| All sites | 0.86 | 0.79 to 0.92 | <0.001 |
| Hospitalist | 0.79 | 0.73 to 0.86 | <0.001 |
| CTUs | 0.91 | 0.83 to 1.01 | 0.078 |
| Expenditure on routine lab test (β coefficient) | |||
| All sites | −0.14 | -0.21 to −0.07 | <0.001 |
| Hospitalist | −0.24 | -0.32 to −0.15 | <0.001 |
| CTUs | −0.06 | -0.15 to 0.03 | 0.193 |
| All common tests (IRR) | |||
| All sites | 0.85 | 0.79 to 0.92 | <0.001 |
| Hospitalist | 0.78 | 0.71 to 0.84 | <0.001 |
| CTUs | 0.92 | 0.83 to 1.03 | 0.142 |
| Routine test-free days (IRR) | |||
| All sites | 1.2 | 1.10 to 1.30 | <0.001 |
| Hospitalist | 1.11 | 1.06 to 1.20 | <0.001 |
| CTUs | 1.35 | 1.11 to 1.65 | 0.006 |
| All common test-free hospital (IRR) patient-days | |||
| All sites | 1.2 | 1.11 to 1.32 | <0.001 |
| Hospitalist | 1.13 | 1.06 to 1.20 | <0.001 |
| CTUs | 1.4 | 1.11 to 1.72 | 0.007 |
β coefficient for cost of routine tests. Routine panel: complete blood count and differential, electrolytes, creatinine, urea, international normalised ratio and partial thromboplastin time; ‘all tests’: list of the top 80 tests ordered at those sites.
CTU, clinical teaching unit; IRR, incidence rate ratio.