July 3 (HealthDay News) -- In 2006, more than 1.2 million Americans -- roughly equivalent to the population of Dallas -- were hospitalized for pneumonia, a federal government analysis of hospital admissions and costs found.

Pneumonia was second only to childbirth as the most common reason for admission to hospital, and treating these lung infections cost hospitals more than $10 billion in 2006, said the latest News and Numbers from the Agency for Healthcare Research and Quality (AHRQ).

The disease occurs when the lungs fill with fluid from infection or inflammation caused by bacteria or a virus. Pneumonia can be especially deadly among the elderly.

The AHRQ analysis of 2006 data revealed the following hospital admissions and costs for other common conditions:

• Hardening of the arteries: 1,198,000, $17 billion
• Congestive heart failure: 1,099,000, $11 billion
• Chest pain: 857,000, $4 billion
• Injuries to mothers during birth: 818.000, $2 billion
• Other complications of labor and delivery: 767,000, $3 billion
• Heart rhythm problems: 749,000, $7 billion
• Osteoarthritis: 735,000, $10 billion
• Heart attack: 675,000, $12 billion

The analysis is based on 2006 data in HCUPnet, AHRQ's free, online query system based on information from the Healthcare Cost and Utilization Project.

SOURCE: U.S. Agency for Healthcare Research and Quality, news release, July 2, 2008