It's only one study based on the health data of one unnamed state. But if the results of the Truven Health Analytics study are at all typical of the general population, then insurers offering coverage through health care reform exchanges should be braced for some very high utilization numbers by an unexpectedly older consumer population.

Truven said it used the data provided by "a large health plan to investigate demographics, risk, financial factors, and utilization patterns in the exchange population of its state." The results of the analysis suggest that some of the basic predictions about those who would purchase coverage through an exchange might have been way off. Truven did not identify either the state or the health plan.

Report findings include:

• Exchange Attracted Older Enrollees: The average enrollee age in the state that was chosen for the study was 46 for the exchange population and 44 for those off the exchanges. Only one plan – the catastrophic level – had an average age under 44 (31 years).

• More Admissions, ER Visits: Exchange enrollees had a whopping 39 percent more admissions and 64 percent more emergency department visits per 1,000 enrollees than non-exchange insureds. Medical and prescription drug utilization increased as the plan design level increased.

• Higher Rate of Chronic Conditions: Exchange enrollees had 44 percent more instances of congestive heart failure and 39 percent more diabetes cases in exchange members. Additionally, exchange enrollees experienced more seizure disorders and convulsions (26 percent), asthma (21 percent), and major depressive disorder (8 percent) versus non-exchange counterparts.

• Silver Plans Dominate Exchanges: Silver plans (including both standard silver and cost-sharing reduction plans) are the preferred plan of choice for exchange enrollees, with an 82 percent market share. Bronze enrollees accounted for just 6 percent, while platinum had 4 percent of the market.

"Now, more than ever, health plan leaders need to understand details about their unique populations to create appropriate product strategies and plan designs for the future," said Barbara Graovac, senior vice president at Truven Health Analytics. "With this snapshot of one state's exchange population, it becomes clear how profound the differences between an exchange and off-exchange health plan population can be, and, how different reality is from initial predictions."