Measuring hospital readmissions within seven days, instead of the typical 30, would more accurately assess the quality of factors the hospital can control, according to a study published in the October issue of Health Affairs.

The study, led by David L. Chin, PhD, a postdoctoral scholar at the Center for Healthcare Policy and Research, University of California, Davis, examined unplanned inpatient readmissions data from Arizona, California, Florida and New York, states chosen for having large, diverse populations, for Medicare beneficiaries for three conditions: acute myocardial infarction, heart failure, and pneumonia.

What they found is variation between hospitals was highest on the first day after discharge and declined rapidly before leveling off at seven days.

“Taken together, these findings suggest that a five-to-seven-day ascertainment interval would better capture hospital-attributable readmissions, particularly when compared to intervals of 30, 60 or 90 days,” Chin and his coauthors wrote.

The study also suggested the current risk-standardized readmission models used by CMS, which adjust only for patient age, sex and clinical characteristics, are inadequate, arguing that adjusting for socioeconomic factors largely explained most readmissions after seven days.

“This suggests that much of the presumed hospital quality signal at thirty days and beyond could be attributable to characteristics of the communities within which hospitals are situated,” Chin and his coauthors wrote.

The question for policymakers, the study said, is whether they want to encourage hospitals to take responsibility for follow-up care or inform patients about a hospital’s quality. If the answer is the latter, then the study argued for measuring readmissions at an interval of no more than seven days.

Beyond adjusting quality measures, the study offered some direction for efforts to limit readmissions. With the hospital quality signal being higher in the first five days, Chin suggested post-discharge follow-up care could be the most beneficial in that time period.