Federal PPACA health insurance exchanges attracted five timesmore growth than did state exchanges for the 2015 insurance yearand experienced significantly less attrition among those enrolledlast year.

That’s what an Avalere analysis of enrollment data reveals.The study raises as-yet-unanswered questions about why federalexchanges are more effective at retaining existing enrollees andattracting new customers. It also adds further evidence to theemerging trend that residents in states with a stronger federalpresence are receiving better health care.

Avalere reported that federally run exchanges retained 78percent of 2014 enrollees and grew by a total of 61 percentcompared to the number covered in 2014. State exchanges retained 69percent of enrollees and grew by 12 percent overall for 2015.

“It’s unclear why state-based exchanges saw higheryear-over-year attrition among their enrollees,” Avalere said. “Onepossibility is that state exchanges had more enrollees whoover-reported income in 2014. For instance, California shiftedabout 200,000 exchange enrollees into Medicaid for 2015. However,it’s unclear why state-run exchanges would have disproportionatelyexperienced such corrections.”

Another factor could be the initial technical difficulties thefederal website experienced in its first year of operation.

“Some of the higher 2015 enrollment may be attributed to initialtechnological issues with HealthCare.gov that may have depressed2014 enrollment, however that alone doesn’t explain why state-runexchanges did so poorly, relative to the federally-facilitatedexchange states,” said Caroline Pearson, senior vicepresident at Avalere.

Yet the federal presence does seem to have its own effect.Earlier studies have shown that, in states where Medicaid expanded,more residents found health insurance, and care for those withchronic diseases like diabetes, showed improvement compared to thestates that decided not to expand Medicaid.

Avalere’s takeaway is that states that operate their ownexchanges are generally failing to connect uninsured residents withcoverage at the levels they had anticipated.

“State-run exchanges lost more ground with enrollment in 2015,making it even harder to achieve annual goals for enrollmentgrowth,” said Elizabeth Carpenter, director at Avalere.

State retention and growth performance varied among the largestindividual states based upon whether they ran their own exchangesor availed themselves of the federal mode, Avalere found.

“Large federally facilitated states like Florida and Texasincreased enrollment by 62 percent and 64 percent respectively.Conversely, large enrollment state-run exchanges like Californiaand New York increased enrollment by 1 percent and 10 percentrespectively,” Avalere reported.