What it means to you: Five years ago, a New England Journal of Medicine article reported on how nursing staff levels affect patient health and survival. More nurses meant a two-to-25-percent reduction in adverse patient outcomes, such as urinary tract infections and pneumonia. Newer studies are reporting similar correlations between staffing levels and HAI rates.

The scoop: Staffing a hospital is expensive, especially in infection-prone areas such as the ICU. But as studies continue to expose the impact nurses have on infection rates, it's easy to see the payoff that comes from staffing up. After all, a single patient's HAI can cost as much as a nurse's annual salary. Here are two reasons to monitor the number of nurses on the floor:

· Swiss researchers followed nearly 1,000 patients who were on respirators over a four-year period and compared ventilator-associated pneumonia (VAP) infection rates to nurse staffing rates. The result: A higher risk of late-onset VAP was associated with a lower nurse-to-patient ratio. The study's authors speculated that harried nurses were too busy to comply with proper hygiene methods, provide the best care or follow approved isolation methods, therefore increasing the risk of VAP. Read the study or a New York Times article about it.

· A study published in Medical Care examines several patient outcomes related to nursing staffing levels. Higher staffing levels were associated with lower levels of central line-associated bloodstream infections (CLBSI) and VAP; increased overtime led to higher rates of catheter-associated urinary tract infections but a lower CLBSI risk.

Learn more: Read about how the working environment affects patient safety in this comprehensive report from the Agency for Healthcare Research and Quality that compiles data and conclusions from earlier studies.