Calling health-care spending the “single biggest financial issue facing the nation,” a group of four national health insurers announced plans Tuesday to pool more than 5 billion health care claims into a single database that researchers can mine to identify trends in cost, utilization and intensity of care, BusinessInsurance.com reported. The nonprofit Health Care Cost Institute will oversee the database created using data from four insurers: Aetna Inc., Humana Inc., Kaiser Permanente and UnitedHealth Group Inc. The database will include government data from Medicare and Medicare Advantage plans, and it may eventually include information from other private insurers. The institute will release public “scorecards” twice a year summarizing national trends in the data, as well as information on a handful of specific geographic regions.