The increasing use of hospital services may be contributing more to high readmission rates than the severity of patients' conditions or the care they receive after being discharged, according to researchers at the Harvard School of Public Health. The study, which appears in the Dec. 15 issue of the New England Journal of Medicine, is the latest research on a hot-button healthcare issue related to cost and quality of care. The Centers for Medicaid and Medicare Services says the focus on readmission rates is pivotal because one out of three Medicare beneficiaries who leave the hospital today will be back in the hospital within a month.