Most of the urgent readmissions are unavoidable. This study developed a method that used observed urgent readmission rates to compare the latent avoidable readmission rates between the two hospitals.
To compare two hospitals, we identified all proportions of urgent readmissions deemed avoidable at each hospital making their avoidable readmission rates significantly different. We then calculated the probability that any of these conditions occurred. We applied this method to 25 randomly selected Ontario acute-care hospitals in 2008.
The hospitals had a median 30-day urgent readmission rate of 10.8% (interquartile [IQR] 9.7-12.8%). The median P-value of the 300 hospital-hospital comparisons for 30-day urgent readmission rate was 0.05 (interquartile range [IQR] 0.0005-0.31). In contrast, the median probability that hospitals with the lower urgent 30-day readmission rate outperformed their comparator hospital with respect to avoidable readmissions was only 0.161 (IQR 0.079-0.274).
Urgent readmission rates can be used to estimate the probability that avoidable readmission rates differ significantly between the two hospitals. The probability that avoidable readmission rates differ significantly between hospitals is small even when significant differences in urgent 30-day readmission rates exist. Our results show that 30-day urgent readmission rates should be used very cautiously to compare hospital quality of care.