In 2002, rates had increased by nearly 15 percent for single coverage and 13 percent for family coverage 2002. Since then, increases have generally moderated, a Kaiser chart shows.

Since the Affordable Care Act was signed in 2010, Zaharuk notes in an interview that rates “bounced around a little bit,” but lately have moderated. Increases in 2012 were just under 4 percent for single coverage and just over 4 percent for family coverage.

Zaharuk says it is a “very unsettled time” for gauging healthcare costs. He says the recent reduced premium growth is a positive for buyers and the industry, but part of the cause behind the trend is the economy. For example, he notes that businesses paring down plans lowers premiums, but also transfers more out-of-pocket costs to consumers. This, in turn, helps lead to lower utilization, which also lowers premiums, but could mean that people are simply putting off care as their share of costs climb.

The Moody's analysis states, “There is no clear data to explain the reason for lower utilization, but it appears to be a combination of the poor economy, resulting in individuals foregoing or delaying healthcare, and lower benefits, which result in higher out-of-pocket costs to individuals.”

But for now, the trends keeping premium growth in check have also contributed to health insurers' positive earnings results through the first six months of the year, Moody's says in its analysis, adding that it expects continued strong earnings for the remainder of 2013.

Beyond this year, though, Moody's says, “Unfortunately, we cannot expect similar premium, utilization and earnings results for 2014 because of the uncertainty regarding major provisions of the Affordable Care Act (ACA) that will take effect next year, as well as the prospects for an improved economy, which has historically led to increased medical care and costs.”

Zaharuk says there is not enough data available yet to determine how ACA provisions such as mandates for people to buy coverage will impact rates.

The Moody's analysis notes, “The Congressional Budget Office projects that of the 7 million it expects will obtain health insurance on the exchanges, approximately 4 million will come from the ranks of those currently uninsured. These individuals are likely to have higher medical utilization in the first year of coverage. Similarly, the 9 million individuals the CBO projects will obtain insurance coverage through the expansion of Medicaid are also likely to incur higher medical costs.”