Table 1.
Combined AMI, HF, and PNA Matching Results
| Covariates (percent unless noted) | Combined medical | |||||||
|---|---|---|---|---|---|---|---|---|
| Major teaching cases (N = 203,922) | Matched major teaching cases (N = 203,922) | Matched non-teaching controls (N = 203,922) | All non-teaching controls (N = 1,049,037) | Std. Diff.* before match | P value before match | Std. Diff.* after match | P value after match | |
| Age on admission (years, mean) | 80.1 | 80.1 | 80.1 | 80.1 | 0.00 | 0.0693 | 0.00 | 0.0289 |
| Age 85+ | 34.45 | 34.45 | 34.46 | 33.70 | 0.02 | < 0.0001 | 0.00 | 0.9606 |
| Sex (% male) | 47.74 | 47.74 | 48.08 | 47.47 | 0.01 | 0.0248 | − 0.01 | 0.0336 |
| Race (% non-Hispanic white) | 72.64 | 72.64 | 75.01 | 85.18 | − 0.31 | < 0.0001 | − 0.06 | < 0.0001 |
| Race (% black) | 17.61 | 17.61 | 16.02 | 7.14 | 0.32 | < 0.0001 | 0.05 | < 0.0001 |
| Emergent admission | 87.68 | 87.68 | 87.03 | 75.52 | 0.32 | < 0.0001 | 0.02 | < 0.0001 |
| Transfer from other hospital’s ED | 0.07 | 0.07 | 0.07 | 0.08 | 0.00 | 0.1749 | 0.00 | 0.7259 |
| Admission risk of 30-day death, % | 12.1 | 12.1 | 12.0 | 12.0 | 0.01 | 0.0064 | 0.00 | 0.7169 |
| Principal diagnosis categories | ||||||||
| Acute myocardial infarction | ||||||||
| Anterior STEMI | 1.74 | 1.74 | 1.74 | 1.79 | 0.00 | 0.1617 | 0.00 | 1.0000 |
| Other location STEMI | 2.73 | 2.73 | 2.73 | 2.76 | 0.00 | 0.5591 | 0.00 | 1.0000 |
| NSTEMI or unspecified MI | 17.09 | 17.09 | 17.09 | 18.06 | − 0.03 | < 0.0001 | 0.00 | 1.0000 |
| Pneumonia | ||||||||
| PNA due to anaerobes or Gram-negative bacteria | 1.06 | 1.06 | 1.06 | 1.06 | 0.00 | 0.8779 | 0.00 | 1.0000 |
| Pneumonia due to H. influenzae | 0.09 | 0.09 | 0.09 | 0.12 | − 0.01 | < 0.0001 | 0.00 | 1.0000 |
| Legionnaire’s disease | 0.10 | 0.10 | 0.10 | 0.04 | 0.02 | < 0.0001 | 0.00 | 1.0000 |
| Pneumonia due to MRSA | 0.56 | 0.56 | 0.56 | 0.77 | − 0.03 | < 0.0001 | 0.00 | 1.0000 |
| Pneumonia, other | 25.28 | 25.28 | 25.28 | 31.59 | − 0.14 | < 0.0001 | 0.00 | 1.0000 |
| Pneumococcal pneumonia | 0.38 | 0.38 | 0.38 | 0.41 | 0.00 | < 0.0001 | 0.00 | 1.0000 |
| Pneumonia due to Pseudomonas | 0.45 | 0.45 | 0.45 | 0.52 | − 0.01 | < 0.0001 | 0.00 | 1.0000 |
| Streptococcal pneumonia | 0.11 | 0.11 | 0.11 | 0.14 | − 0.01 | 0.0126 | 0.00 | 1.0000 |
| Staphylococcal pneumonia | 0.04 | 0.04 | 0.04 | 0.05 | − 0.01 | 0.0414 | 0.00 | 1.0000 |
| Viral pneumonia | 1.37 | 1.37 | 1.37 | 0.89 | 0.05 | < 0.0001 | 0.00 | 1.0000 |
| Aspiration pneumonia | 7.31 | 7.31 | 7.31 | 7.62 | − 0.01 | < 0.0001 | 0.00 | 1.0000 |
| Heart failure | ||||||||
| HF with chronic kidney disease | 2.83 | 2.83 | 2.83 | 1.64 | 0.08 | < 0.0001 | 0.00 | 1.0000 |
| HF with hypertension | 1.11 | 1.11 | 1.11 | 0.87 | 0.02 | < 0.0001 | 0.00 | 1.0000 |
| HF, other | 37.73 | 37.73 | 37.73 | 31.69 | 0.13 | < 0.0001 | 0.00 | 1.0000 |
| Comorbidities | ||||||||
| Hx of hypertension | 89.87 | 89.87 | 89.28 | 89.11 | 0.02 | < 0.0001 | 0.02 | < 0.0001 |
| Hx of diabetes | 48.39 | 48.39 | 47.64 | 45.24 | 0.06 | < 0.0001 | 0.01 | < 0.0001 |
| Hx of HF | 44.65 | 44.65 | 44.68 | 39.62 | 0.10 | < 0.0001 | 0.00 | 0.8923 |
| Hx of COPD | 37.49 | 37.49 | 37.33 | 44.50 | − 0.14 | < 0.0001 | 0.00 | 0.2798 |
| Hx of renal failure | 32.21 | 32.21 | 31.41 | 28.45 | 0.08 | < 0.0001 | 0.02 | < 0.0001 |
| Hx of dementia | 26.62 | 26.62 | 25.87 | 27.18 | − 0.01 | < 0.0001 | 0.02 | < 0.0001 |
| Hx of stroke | 9.14 | 9.14 | 8.93 | 7.86 | 0.05 | < 0.0001 | 0.01 | 0.0224 |
| Hx of unstable angina | 8.13 | 8.13 | 7.64 | 6.64 | 0.06 | < 0.0001 | 0.02 | < 0.0001 |
| Hx of cancer | 7.13 | 7.13 | 6.43 | 6.01 | 0.05 | < 0.0001 | 0.03 | < 0.0001 |
| Hx of AMI | 4.47 | 4.47 | 4.20 | 4.96 | − 0.02 | < 0.0001 | 0.01 | < 0.0001 |
| Hospital characteristics (not included in the matching algorithm) | ||||||||
| No. of hospitals | 339 | 339 | 2439 | 2533 | ||||
| RTB ratio (mean) | 0.50 | 0.50 | 0.00 | 0.00 | 2.95 | < 0.0001 | 2.95 | < 0.0001 |
| COTH membership (%) | 68.81 | 68.81 | 0.00 | 0.00 | – | – | – | – |
| Nurse-to-bed ratio ≥ 1 (%) | 85.62 | 85.62 | 71.21 | 68.97 | 0.41 | < 0.0001 | 0.35 | < 0.0001 |
| Cardiac technology (%) | 58.60 | 58.60 | 20.08 | 21.76 | 0.81 | < 0.0001 | 0.85 | < 0.0001 |
| Size > 250 beds (%) | 85.28 | 85.28 | 34.94 | 34.75 | 1.20 | < 0.0001 | 1.20 | < 0.0001 |
The table reports balance for selected covariates after matching. All matched covariates met balance criteria. Complete balance tables with all variables, along with individual tables for AMI, HF, and PNA, are provided in Appendix Tables 9a–9c
Hx history
*Standardized difference in units of before-match standard deviation