Table 2.
Predictors of Postdischarge Outpatient International Normalized Ratio Testing
| Variable | Unadjusted RR (95% CI) | P Value | Adjusted RR (95% CI) | P Value |
|---|---|---|---|---|
| Age, per 5 years | 1.01 (1.00‐1.01) | 0.04 | 1.00 (1.00‐1.01) | 0.14 |
| Male sex | 0.98 (0.97‐1.00) | 0.02 | 0.98 (0.97‐1.00) | 0.02 |
| Race | ||||
| Black | 0.92 (0.88‐0.96) | <0.001 | 0.93 (0.89‐0.97) | <0.001 |
| White | 1.00 [Reference] | 1.00 [Reference] | ||
| Other/unknown | 0.97 (0.94‐1.01) | 0.11 | 0.98 (0.95‐1.01) | 0.16 |
| US geographic region | ||||
| Midwest | 1.03 (1.01‐1.05) | <0.001 | 1.03 (1.01‐1.05) | <0.001 |
| Northeast | 1.02 (1.00‐1.04) | 0.02 | 1.02 (1.00‐1.04) | 0.05 |
| South | 1.00 [Reference] | 1.00 [Reference] | ||
| West | 0.98 (0.95‐1.02) | 0.31 | 0.98 (0.95‐1.02) | 0.35 |
| Medical history | ||||
| Chronic obstructive pulmonary disease | 0.99 (0.97‐1.00) | 0.16 | 0.99 (0.98‐1.01) | 0.49 |
| Chronic renal insufficiency | 0.98 (0.97‐1.00) | 0.03 | 0.99 (0.97‐1.01) | 0.29 |
| Coronary artery disease | 1.01 (0.99‐1.02) | 0.41 | 1.01 (0.99‐1.02) | 0.53 |
| Diabetes mellitus | 0.98 (0.96‐0.99) | 0.002 | 0.98 (0.97‐1.00) | 0.03 |
| Dyspnea | 0.98 (0.96‐1.01) | 0.18 | 0.98 (0.95‐1.00) | 0.04 |
| Fatigue | 1.01 (1.00‐1.03) | 0.10 | 1.01 (1.00‐1.03) | 0.13 |
| Hyperlipidemia | 1.02 (1.00‐1.03) | 0.02 | 1.02 (1.00‐1.03) | 0.07 |
| Hypertension | 1.00 (0.99‐1.02) | 0.90 | 1.00 (0.99‐1.02) | 0.68 |
| Myocardial infarction | 1.01 (0.99‐1.02) | 0.40 | 1.00 (0.99‐1.02) | 0.64 |
| Peripheral vascular disease | 1.00 (0.98‐1.02) | 0.98 | 1.00 (0.98‐1.02) | 0.95 |
| Rales | 1.00 (0.98‐1.01) | 0.64 | 1.00 (0.98‐1.01) | 0.59 |
| Stroke or transient ischemic attack | 1.00 (0.98‐1.01) | 0.72 | 1.00 (0.98‐1.01) | 0.64 |
| Warfarin indication | ||||
| Atrial fibrillation | 1.00 [Reference] | 1.00 [Reference] | ||
| Atrial fibrillation and valvular heart disease | 1.05 (1.03‐1.06) | <0.001 | 1.04 (1.02‐1.06) | <0.001 |
| Valvular heart disease | 1.03 (1.01‐1.05) | 0.02 | 1.03 (1.01‐1.05) | 0.01 |
| Discharge medications | ||||
| ACE inhibitor or ARB | 1.01 (0.99‐1.02) | 0.35 | 1.00 (0.98‐1.02) | 0.97 |
| Aspirin | 1.00 (0.99‐1.02) | 0.56 | 1.00 (0.98‐1.02) | 0.98 |
| β‐Blocker | 1.01 (1.00‐1.03) | 0.07 | 1.01 (1.00‐1.03) | 0.19 |
| Clopidogrel | 1.01 (0.97‐1.04) | 0.67 | 1.01 (0.97‐1.04) | 0.76 |
| Diuretic | 1.03 (1.00‐1.06) | 0.04 | 1.02 (0.99‐1.05) | 0.11 |
| Lipid‐lowering agent | 1.01 (0.99‐1.02) | 0.23 | 1.00 (0.98‐1.02) | 0.92 |
| Index length of stay >7 days | 1.00 (0.98‐1.02) | 0.86 | 1.00 (0.99‐1.02) | 0.65 |
| Hospitalized during ascertainment period | 0.96 (0.94‐0.98) | <0.001 | 0.96 (0.94‐0.98) | <0.001 |
| Index year | ||||
| 2001 | 1.00 [Reference] | 1.00 [Reference] | ||
| 2002 | 0.95 (0.92‐0.98) | 0.002 | 0.95 (0.92‐0.98) | 0.003 |
| 2003 | 0.96 (0.93‐0.99) | 0.008 | 0.96 (0.92‐0.99) | 0.007 |
| 2004 | 0.96 (0.93‐1.00) | 0.03 | 0.96 (0.93‐1.00) | 0.03 |
| Ejection fraction | ||||
| Mildly impaired (>40%) | 1.00 [Reference] | 1.00 [Reference] | ||
| Moderately impaired (26%–40%) | 1.00 (0.99‐1.02) | 0.64 | 1.00 (0.99‐1.02) | 0.60 |
| Severely impaired (≤25%) | 1.00 (0.98‐1.01) | 0.62 | 1.00 (0.98‐1.02) | 0.79 |
| Missing | 0.97 (0.94‐0.99) | 0.004 | 0.97 (0.95‐0.99) | 0.02 |
| Heart rate, bpm | ||||
| <80 | 1.00 [Reference] | 1.00 [Reference] | ||
| 80–100 | 1.01 (0.99‐1.02) | 0.50 | 1.01 (0.99‐1.02) | 0.39 |
| >100 | 1.00 (0.99‐1.02) | 0.68 | 1.01 (0.99‐1.03) | 0.46 |
| Hemoglobin, g/dL | ||||
| <9 | 1.03 (0.99‐1.06) | 0.15 | 1.04 (1.00‐1.08) | 0.05 |
| 9–11 | 0.99 (0.98‐1.01) | 0.49 | 1.00 (0.98‐1.01) | 0.65 |
| >11 | 1.00 [Reference] | 1.00 [Reference] | ||
| Serum creatinine, mg/dL | ||||
| <1.5 | 1.00 [Reference] | 1.00 [Reference] | ||
| 1.5–2.0 | 1.00 (0.98‐1.01) | 0.65 | 1.00 (0.98‐1.02) | 0.83 |
| >2.0 | 0.97 (0.95‐0.99) | 0.01 | 0.99 (0.96‐1.01) | 0.37 |
| Serum sodium, mEq/L | ||||
| <135 | 1.00 (0.98‐1.02) | 0.97 | 1.00 (0.98‐1.02) | 0.79 |
| 135–145 | 1.00 [Reference] | 1.00 [Reference] | ||
| >145 | 0.95 (0.89‐1.01) | 0.09 | 0.95 (0.90‐1.01) | 0.12 |
| Systolic blood pressure, mm Hg | ||||
| <110 | 0.99 (0.97‐1.01) | 0.45 | 1.00 (0.97‐1.02) | 0.70 |
| 110–150 | 1.00 [Reference] | 1.00 [Reference] | ||
| >150 | 0.98 (0.97‐1.00) | 0.06 | 0.99 (0.97‐1.00) | 0.08 |
Abbreviations: ACE, angiotensin‐converting enzyme; ARB, angiotensin receptor blocker; CI, confidence interval; RR, risk ratio.