Prediction is very hard, especially about the future: comment on "factors associated with 30-day readmission rates after percutaneous coronary intervention".

BACKGROUND Thirty-day readmission rates have become a publicly reported quality performance measure for congestive heart failure, acute myocardial infarction, and percutaneous coronary intervention (PCI). However, little is known regarding the factors associated with 30-day readmission after PCI. METHODS To assess the demographic, clinical, and procedural factors associated with 30-day readmission rates after PCI, we identified 15, 498 PCI hospitalizations (elective or for acute coronary syndromes) from January 1998 through June 2008 at Saint Marys Hospital, Rochester, Minnesota. All were included in this analysis. Multivariate logistic regression models were used to estimate the adjusted association between demographic, clinical, and procedural variables and 30-day readmission. The association between 30-day readmission and 1-year mortality was estimated using Cox proportional hazards models with readmission as a time-dependent covariate and by using landmark analysis. The main outcome measures were all-cause 30-day readmission to any hospital following PCI and 1-year mortality. RESULTS Overall, 9.4% of PCIs (n = 1459) were readmitted, and 0.68% of PCIs (n = 106) resulted in death within 30 days after discharge. After multivariate analysis, female sex, Medicare insurance, having less than a high school education, unstable angina, cerebrovascular accident or transient ischemic attack, moderate to severe renal disease, chronic obstructive pulmonary disease, peptic ulcer disease, metastatic cancer, and a length of stay of more than 3 days were associated with an increased risk of 30-day readmission after PCI. Thirty-day readmission after PCI was associated with a higher risk of 1-year mortality (adjusted hazard ratio, 1.38; 95% CI, 1.08-1.75; P = .009). CONCLUSIONS Nearly 1 in 10 patients undergoing PCI were readmitted within 30 days. Thirty-day readmission after PCI was associated with a higher risk of 1-year mortality.