Table 3.
Physician age and 30 day patient mortality in patients admitted to hospital, stratified by patient volume
| Physician age | No of admissions (No of physicians*) | Adjusted 30 day mortality rate† (95% CI) | Adjusted odds ratio† (95% CI) | P value |
|---|---|---|---|---|
| Low volume physicians (<90 cases/year ‡ ) | ||||
| Continuous§ | 62 634 (6246) | — | 1.19 (1.14 to 1.23) | <0.001 |
| <40 | 35 540 (3666) | 12.7% (12.3% to 13.0%) | Reference | — |
| 40-49 | 16 988 (2070) | 14.6% (14.0% to 15.1%) | 1.24 (1.15 to 1.34) | <0.001 |
| 50-59 | 7259 (941) | 16.0% (15.1% to 16.8%) | 1.44 (1.30 to 1.60) | <0.001 |
| ≥60 | 2847 (388) | 17.0% (15.5% to 18.4%) | 1.59 (1.36 to 1.85) | <0.001 |
| Medium volume physicians (90-200 cases/year ‡ ) | ||||
| Continuous§ | 189 902 (6208) | — | 1.06 (1.03 to 1.09) | <0.001 |
| <40 | 95 824 (3521) | 10.8% (10.6% to 11.0%) | Reference | — |
| 40-49 | 63 471 (2622) | 11.2% (11.0% to 11.5%) | 1.06 (1.01 to 1.11) | 0.01 |
| 50-59 | 23 031 (986) | 11.2% (10.8% to 11.7%) | 1.06 (0.99 to 1.13) | 0.10 |
| ≥60 | 7574 (318) | 12.5% (11.6% to 13.4%) | 1.23 (1.10 to 1.38) | <0.001 |
| High volume physicians (>201 cases/year ‡ ) | ||||
| Continuous§ | 477 627 (6235) | — | 1.01 (0.99 to 1.03) | 0.29 |
| <40 | 174 760 (2907) | 10.7% (10.6% to 10.8%) | Reference | — |
| 40-49 | 198 363 (3251) | 10.9% (10.8% to 11.1%) | 1.03 (1.004 to 1.06) | 0.03 |
| 50-59 | 84 402 (1362) | 10.8% (10.6% to 11.1%) | 1.02 (0.98 to 1.05) | 0.33 |
| ≥60 | 20 102 (365) | 10.9% (10.4% to 11.4%) | 1.02 (0.96 to 1.09) | 0.51 |
*Total number of physicians varies between continuous and categorical analyses because some physicians moved to higher age category during study period.
†Adjusted for patient and physician characteristics and hospital fixed effects. Standard errors were clustered at physician level.
‡Total number of admissions per physician estimated: our data were 20% random sample of fee-for-service Medicare beneficiaries, Medicare patients overall account for about 40% of all admissions because of medical conditions in the US, and about 70% of all Medicare beneficiaries (including fee-for-service Medicare and Medicare Advantage) are covered by fee-for-service Medicare.
§Estimates from continuous models should be interpreted as average odds ratio across all physician age categories.