If the Office of Management and Budget (OMB) approves, the Agency for Healthcare Research and Quality (AHRQ) will soon establish a "registry of patient registries" (RoPR) to aid researchers doing comparative effectiveness research. The registries referenced in RoPR would include those related to clinical trials and might also encompass patient registries created by healthcare systems and accountable care organizations. AHRQ's proposal, published in the Federal Register, would create a database of the registries used in some observational trials.