When Nurses Go on Strike

In SuperFreakonomics, we wrote about the very mixed evidence concerning health outcomes when doctors go on strike or leave town for conventions. Surprisingly, when doctors disappear for awhile, patients don’t seem to suffer, and maybe the opposite in the short run.
But what about nurses?
A recent study by my friend Jonathan Gruber, an economist at MIT, and co-author Samuel Kleiner, finds that things go haywire when nurses go on strike. From the abstract of their recent NBER working paper:

We utilize a unique data set collected on nurses’ strikes over the 1984 to 2004 period in New York State, and match these strikes to a restricted-use hospital discharge database which provides information on treatment intensity, patient mortality and hospital readmission. Controlling for hospital-specific heterogeneity, patient demographics and disease severity, the results show that nurses’ strikes increase in-hospital mortality by 19.4% and 30-day readmission by 6.5% for patients admitted during a strike, with little change in patient demographics, disease severity or treatment intensity. This study provides some of the first analytical evidence on the effects of health care strikes on patients, and suggests that hospitals functioning during nurses’ strikes are doing so at a lower quality of patient care.

So when nurses strike, the patients who show up at the hospital are more likely to die there and also are more likely to be readmitted to the hospital within 30 days. The obvious concern with this analysis is that the nursing strike might affect the kinds of patients that show up to be treated. If only the sickest patients brave the hospital when nurses strike, their outcomes will be worse whether or not the nurses are there. In other words, the link between nurse strikes and bad outcomes could be spurious.
What I like best about this paper is how Gruber and Kleiner deal with that potential criticism. First, they show that on a range of observable characteristics (types of illness, patient age, percent uninsured, etc.), the patients who come to the hospital during the strikes look a lot like the typical patients. Second, if the relatively healthy patients waited to go to the hospital until after the strike, or went to hospitals in other areas during the strike, there should be evidence in the data, but they don’t find anything.