Late last month, the Nevada Health Co-op became the third casualty among 23 insurance start-ups created under the federal health care law to inject competition for coverage in certain parts of the country.

Set up as nonprofits with consumer-led boards, the co-ops were designed to provide affordable insurance coverage to individuals and small businesses. They were intended under the law to offer alternatives — and hopefully cheaper prices — to the plans sold by large established insurance companies in some regions.