Using data from the American Hospital Association, the state of California, and the Agency for Healthcare Research and Quality, changes in staffing and in quality of care in California hospitals were compared to hospitals in 12 states that didn't have minimum staffing legislation.
Researchers found that California hospitals did increase nurse staffing levels more significantly than hospitals in the other states. Quality measures, however, didn't necessarily rise along with staffing levels.
For example, according to the researchers, "there were no statistically significant changes in either respiratory failure or postoperative sepsis." Other findings showed improvements in some areas, such as failure to rescue, which decreased significantly more in some California hospitals.
The causal relationship between the two factors isn't clear, however, and more research is needed, researchers say.
The California Nurses Association slammed the study, telling California Healthline that the study methodology was flawed and that the results "were not sufficient to support the authors' conclusions. In fact, the evidence derived from these tests points to the improvement in rescuing patients with nursing ratios in place."
But a National Bureau of Economic Research working paper from 2010 drew a similar mixed conclusion, with the authors finding "persuasive evidence that AB394 did have the intended effect of decreasing patient/nurse ratios in hospitals that previously did not meet mandated standards. However, our analysis suggests that patient outcomes did not disproportionately improve in these same hospitals. That is, we find no evidence of a causal impact of the law on patient safety."