All this is courtesy of Austin Frakt:
Low-income African American patients  are up to 43% more likely than their higher-income white counterparts to find themselves back in the hospital within weeks of discharge. As a result, the cost of care for these disadvantaged patients is high, as illustrated by the population of low-income patients who are dually eligible for Medicare and Medicaid. Dually eligible individuals cost twice as much as other Medicare beneficiaries largely because they are 4 times as likely to be readmitted to hospitals for ambulatory care–sensitive conditions. [...] (JAMA study)
Most importantly, many post discharge interventions are fundamentally clinical interventions, delivered by a workforce trained to address clinical issues. Paradoxically, intensifying clinical follow-up care  might actually increase admissions; outpatient medical providers often do not have the tools to address the underlying social causes of poor health and have no choice but to refer these patients back to the hospital when they inevitably fall ill. (JAMA study)
Penalizing providers who deal with the problem:
Because the measure used for Medicare’s penalty is not adjusted for patients’ socioeconomic status (SES), and because patients with lower SES experience higher rates of readmissions, safety-net hospitals on average receive higher penalties under the current regime….
Experts  noted the futility of discharging vulnerable patients into communities lacking strong networks of primary care and the community support systems necessary to aid patients in their recovery. (Commonwealth study)