U.S. spending on health insurance grew at an accelerated rate in 2011, breaking a two-year trend of smaller cost increases. The culprit, a new study suggests, is not Americans seeking more treatment but rather rapid growth in the price of medical care. Spending for private health insurance surged by 4.6 percent in 2011, according to a report from the Health Care Cost Institute. That growth rate is faster than the rest of the economy and higher than the previous year, which had 3.8 percent growth. Average spending on a private insurance patient rose to $4,547 in 2011, compared with $4,349...