Bed days are defined as spending one-half or more days in bed because of injury or illness, excluding hospitalization. Among adults with doctor-diagnosed arthritis in 2012, 22.4 million, or 9.5% of the entire adult population experienced bed days. These individuals reported an average of 24.0 bed days in the past 12 months. This is far higher than the 14.5 bed days reported by adults with any medical condition. This resulted in 537.6 million bed days overall, or 53% of the 1 trillion bed days among adults reporting any medical condition. Females and those 75 years and older had higher than average bed days. (Reference Table 4.7 PDF CSV)