To investigate whether hospital readmission after admission for heart failure (), myocardial infarction (), and pneumonia varies by season.
All patients in 2005–2009 Healthcare Cost and Utilization Project State Inpatient Databases for New York and California hospitalized for ,, or pneumonia.
The relationship between discharge season and unplanned readmission within 30 days was evaluated using multivariate modified Poisson regression.
Cohorts included 869,512 patients with , 448,945 patients with , and 813,593 patients with pneumonia. While admissions varied widely by season, readmission rates only ranged from 25.0 percent (spring) to 25.6 percent (winter) for ( > .05), 18.9 percent (summer) to 20.0 percent (winter) for ( < .001), and 19.4 percent (spring) to 20.3 percent (summer) for pneumonia ( < .001). In adjusted models, in New York, there was lower readmission in spring and fall (: 0.98, 95% : 0.96–0.99 for both) after admission for and higher readmission in spring (: 1.04, 95% : 1.01–1.07) after . In California, there was lower readmission in spring and winter (: 0.95, 95% : 0.93–0.96 and : 0.96, 95% : 0.94–0.98, respectively) after pneumonia.
Given marked seasonality in incidence and mortality of ,, and pneumonia, the modest seasonality in readmissions suggests that readmissions may be more related to non–seasonally dependent factors than to the seasonal nature of these diseases.