While 66 of the 100 largest hospitals in the United States offer consumers mobile health apps, only 2 percent of patients are using them, according to a new report published on Wednesday by Accenture that also found that failure to focus apps on services consumers want most could cost each hospital more than $100 million a year in lost revenue. In its "Losing Patience: Why Healthcare Providers Need to Up Their Mobile Game" report, the consultancy found that 38 of those top U.S. hospitals have developed health apps in-house rather than by hiring a mobile app vendor.