By BOB WACHTER

How many nurses does it take to care for a hospitalized patient? No, that’s not a bad version of a light bulb joke; it’s a serious question, with thousands of lives and billions of dollars resting on the answer. Several studies (such as here and here) published over the last decade have shown that having more nurses per patient is associated with fewer complications and lower mortality. It makes sense.

Yet these studies have been criticized on several grounds. First, they examined staffing levels for hospitals as a whole, not at the level of individual units. Secondly, they compared well-staffed hospitals against poorly staffed ones, raising the possibility that staffing levels were a mere marker for other aspects of quality such as leadership commitment or funding. Finally, they based their findings on average patient load, failing to take into account patient turnover.

Last week’s NEJM contains the best study to date on this crucial issue. It examined nearly 200,000 admissions to 43 units in a “high quality hospital.” While the authors don’t name the hospital, they do tell us that the institution is a US News top rated medical center, has achieved nursing “Magnet” status, and, during the study period, had a mortality rate nearly 40 percent below that predicted for its case-mix. In other words, it was no laggard.

As one could guess from its pedigree and outcomes, the hospital’s approach to nurse staffing was not stingy. Of 176,000 nursing shifts during the study period, only 16 percent were significantly below the established target (the targets are presumably based on patient volume and acuity, but are not well described in the paper). The authors found that patients who experienced a single understaffed shift had a 2 percent higher mortality rate than ones who didn’t. Each additional understaffed shift carried a similar, and additive, risk. This means that the one-in-three patients who experienced three such shifts during their hospital stay had a 6 percent higher mortality than the few patients who didn’t experience any. If the FDA discovered that a new medication was associated with a 2 percent excess mortality rate, you can bet that the agency would withdraw it from the market faster than you could say “Sidney Wolfe.”

The effects of high patient turnover were even more striking. Exposure to a shift with unusually high turnover (7 percent of all shifts met this definition) was associated with a 4 percent increased odds of death. Apparently, patient turnover – admissions, discharges, and transfers – is to hospital units and nurses as takeoffs and landings are to airplanes and flight crews: a single 5-hour flight (one takeoff/landing) is far less stressful, and much safer, than five hour-long flights (5 takeoffs/landings).

As the authors note, this study should end the debate about the impact of nurse staffing on patient outcomes. The senior author, Mayo’s Marcelline Harris, said of the study: “It moves it away from questioning whether nurse staffing impacts patient outcomes, to focusing on the most effective ways to deliver nursing care and how current and emerging payment systems can reward hospitals’ efforts to ensure adequate staffing.” I agree.

As I discussed recently, virtually all research on the relationship between hospital staffing and outcomes comes from the field of nursing. This is because hospitals hire nurses, whereas physicians have traditionally been free to determine their own workloads and staffing ratios. But this is changing: since nearly half of American hospitalists are now employed by their hospitals, the field’s unprecedented growth has begun to catalyze a parallel debate: how many patients should a hospitalist care for? And a similar discussion, with an educational twist, has been a subtext in the controversy over the ACGME’s duty hours regulations. Though most of the attention has been on the work-hour rules, the regulations also set new limits on patients- and admissions-per-resident. And, with more and more physicians becoming hospital employees, expect the staffing ratio debate – for both nurses and doctors – to grow increasingly contentious, particularly as hospital profit margins evaporate. After all, labor costs represent hospitals’ largest expense.

Even today, nurse staffing is the subject of fierce negotiations between hospital management and nurses (or their unions) in many states, but not so much in California. In 2004, the California legislature bowed to pressure from the California Nurses Association to mandate nurse-to-patient ratios: 1:2 in ICUs and 1:5 on med-surg units. Although the law was controversial, it has probably saved lives – a 2006 survey found that a hospital nurse in California cared for one fewer patient per shift than a comparable nurse in New Jersey or Pennsylvania. The companion study estimated that raising those states’ staffing levels to match California’s would have saved nearly 500 lives over a two-year period. Since California’s law went into effect, 14 other states have followed suit.

While having adequate nurse staffing is a lifesaver, we can’t ignore its costs. With the average nurse’s salary topping $100,000 at hospitals like mine, bumping the ratio can easily take a multi-million dollar bite out of the budget. One wonders whether there is another way.

Which brings me to Louise.

Several years ago, investigators at Boston University, led by Dr. Brian Jack, launched a comprehensive program to improve hospital discharges and decrease readmission rates. Dubbed Project RED (“Re-Engineered Discharge”), the protocol involved giving patients intensive pre-discharge counseling, a customized discharge document, an early post-discharge phone call, and a rapid follow-up appointment. The investigators demonstrated a 30 percent decrease in readmissions and – even before the upcoming Medicare payment changes that will penalize hospitals for excess readmissions – modest cost-savings, $412 per patient. One of the most expensive parts of the intervention was the discharge counseling: an RN spent, on average, nearly 90 minutes with each patient and family, a significant cost.

The BU investigators practice at Boston Medical Center, a safety net hospital that teeters perennially on the financial precipice. I have to believe that this fact influenced their next step: to see whether they could get the benefits of the RED at a lower cost. Turning their attention to the nurse discharge visit, they struck up a collaboration with an informatician at Northeastern University to develop an “animated conversational character” they called Louise.

Louise is pre-programmed with individual patient information, which she combines with disease-specific and general questions. She – a pleasant looking middle-aged woman of unclear race and ethnicity – appears on a computer screen that is wheeled to the patient’s bedside. (You can see multiple clips of Louise interacting with patients here.) Speaking to the patient in a relatively fluent but unmistakable computer voice (with synchronized animation), she might say,

You take Atenolol for your heart… it may make you dizzy… would you like to know more information about taking Atenolol?

Or,

The doctors tell me that your primary condition is atrial fibrillation… it usually causes a rapid heart beat. Do you have any questions about this condition?

Patients answer Louise’s questions by picking choices off a touch-screen interface. She then responds according to her algorithm.

In a recent pilot study, Louise’s performance was equivalent to that of the human discharge coach, while saving nearly $150 per encounter. But would patients accept the idea of having an hour-long conversation with a glorified cartoon?

Well, yes. Most patients found Louise to be personable and responsive. In fact, three out of four patients preferred interacting with Louise to receiving discharge instructions from a live physician or nurse! One patient said,

It was just like a nurse, actually better, because sometimes a nurse just gives you the paper and says, ‘Here you go.’ [She] explains everything.

Another added:

I’ve had problems with, not this hospital, but other hospitals. I wasn’t given the quality time that this lady gave me.

Let’s be clear. While Louise can calmly walk a patient down an algorithmic path, answer simple questions, and test basic understanding, dealing with complex situations, managing ambiguity, and showing empathy are not her forte. Nevertheless, Louise’s success demonstrates that certain functions that we presently call “nursing” can probably be accomplished by other people or technologies, at a lower cost.

Louise’s story should give us pause before we gallop from last week’s NEJM findings to more legislative staffing-ratio mandates. There is no question that the California ratios have saved lives; this week’s study makes that clearer than ever. But in a healthcare system whose costs threaten to bankrupt our nation, mandatory ratios are a blunt, inflexible instrument. Before we race to lock in arbitrary ratios, we need to know how much of our nurses’ precious time is spent on tasks that could be done by other people or technologies? And, when we get around to discussing physician staffing ratios, we’ll need to have similar conversations.

Of course, in a perfect policy environment, one wouldn’t need mandatory staffing ratios at all. Rather, a combination of transparency and performance-based payment strategies would lead hospitals to be intensely motivated to lower their mortality rates and improve their other quality and safety outcomes. While hospitals would likely ensure adequate staffing, they’d also be prompted to find less expensive but effective substitutes for human capital. Moreover, they’d have the freedom to strike an optimal balance among the many potential safety- and quality-oriented expenditures. Sure, it would be great to have perfect nurse staffing, but what if that came at the cost of information technology, or rapid response teams, or bedside ultrasound, or ward-based pharmacists, or teamwork training… or, for that matter, optimal physician staffing. While seductive, mandating one safety-oriented strategy without addressing others can be like squeezing the proverbial balloon.

We don’t have that kind of policy environment – yet – and so, for now, I believe the California-type ratios are a reasonable response to the evidence. But such ratios should have a sunset clause that kicks in after 5-7 years, at which time they should be reconsidered in light of any innovations that have surfaced. Perhaps the next study will show that a slightly smaller nursing workforce, aided by a team of “Louise’s,” will be able to provide high quality and safe care at a lower cost.

This is the holy grail: that the hospital operating in an environment of accountability for outcomes will be driven to approach safety and quality strategically, thoughtfully balancing its own caregiver staffing with its investments in other safety/quality activities. If we can get there, legislatively-mandated staffing ratios would become unnecessary, perhaps even counterproductive.