Understaffing of registered nurses for two consecutive work shifts showed a statistically significant increase in healthcare-associated infections (HAIs), researchers report in a new study.¹

“Clinically, it makes sense because if the understaffing is for only one shift, nurses can manage the workload,” says lead author Jingjing Shang, PhD, RN, associate professor at Columbia University School of Nursing in New York City. “However, if [the unit is understaffed] the whole day, the consequences will show up.”

Shang and colleagues examined “whether [HAIs] and nurse staffing are associated using unit-level staffing data.” Previous studies have suggested there is a link, but “the association between HAIs and nurse staffing are inconsistent and limited by methodological weaknesses,” the authors noted.

They analyzed data from a large urban health system in the period between 2007 and 2012. HAIs were diagnosed using CDC definitions. To allow for the incubation period of pathogens, researchers assessed staffing levels two days before infection onset.

Overall, using a measure of patient-days, 15% of patients “had one shift understaffed, defined as staffing below 80% of the unit media for a shift, and 6.2% had both day and night shifts understaffed. Patients on units with both shifts understaffed were significantly more likely to develop HAIs two days later,” the authors reported. HAIs included in the analysis were urinary tract infections, bloodstream infections, and cases of pneumonia.

“If only one shift was understaffed, the risk was also high but not significant,” Shang says. “In the units that had both day and night shifts understaffed, we definitely saw this significant increase of the infection rate.”

The study also showed an increase in infection risk when units lacked support staff such as licensed practical nurses and nurse assistants. The bottom line for hospital leaders is that dollars saved by cutting staffing will result in the expense and suffering of HAIs.

“In addition to their medical and financial impacts, HAIs also have psychological and social consequences for patients such as depression, anxiety, disability, and job loss,” Shang and colleagues emphasized.

Hospital administrators are the primary audience they wanted to reach with the paper, Shang says, thus its submission to the Journal of Nursing Administration.

The threshold of 80% median unit staffing to define understaffing was drawn from previous research by the authors, serving as the line of demarcation between sufficient nursing levels and increasing risk of HAIs.

As nurse staff levels decrease, the likelihood rises that corners may be cut, resulting in lapses and breaches of infection control measures such as hand hygiene and glove use.

Previous studies are limited in the way they assessed the effect of staffing on nursing, often averaging staffing over the whole hospital, Shang tells Hospital Infection Control & Prevention. “They are not very specific on a unit level,” she says.

The Columbia study sought more precision on the unit and shift level, using payroll data to determine when the nurses clocked in and out, she says.

“The infections in our study are based on CDC definitions,” Shang says. “They are very precise, and are based on lab results, cultures, and symptoms. We measured the staffing very precisely, and the infections are based on clinical outcomes — not administrative data.”

REFERENCE

1. Shang J, Needleman J, Liu J, et al. Nurse Staffing and Healthcare-Associated Infection, Unit-Level Analysis. JONA 2019; 49(5):260-265.