Characteristics of the study hospitals and nurses used as controls are summarized in . Our sample included 161 acute care Pennsylvania hospitals that provided infection data to the PHC4 and nurses who were surveyed and employed in those same hospitals. The average number of beds per hospital was 227, almost half of the hospitals were identified as teaching hospitals, and 40% were high-technology hospitals. On average, nurses cared for 5.7 patients, the average number of patients per hospital was 9,758, and the average number of nurse respondents per hospital was 48. The average age of the nurses across all hospitals was 44 years, and the overwhelming majority (95%) were female. Roughly 38% of the nurses were educated at the baccalaureate level or higher, and the nurses had an average of 17 years of nursing experience. More than one-third of all nurses reported high levels of job-related burnout.
Hospital and nurse characteristics used as controls in this study
Overall, 16 patients per 1,000 acquired some type of infection while hospitalized. The most common infections were urinary tract infections (8.6 per 1,000) and surgical site infections (4.2 per 1,000), followed by gastrointestinal infections (2.5 per 1,000) and pneumonia (2.1 per 1,000) ().
Summary of health care–associated infections (n =161 hospitals)
presents regression coefficients from our models of the relationships among nurse staffing, nurse burnout, and infection rates. Using urinary tract infection rate as our outcome measure and staffing as our covariate of interest, we found a significant staffing coefficient of 0.86 (P = .02); that is, an additional patient assigned to each nurse in a hospital was associated with a 0.86-unit increase (or an increase of nearly 1 per 1,000) in the rate of urinary tract infection. In our study population, this would translate to 1,351 additional infections for each patient added to a nurse’s workload. Using the same model for surgical site infection, we obtained a significant staffing coefficient of 0.93 (P = .04).
Models estimating the effects of nurse staffing and burnout on health care–associated urinary track and surgical site infection
In our second model examining the association between nurse burnout and infection rate, nurse burnout was highly associated with both urinary tract infections (β = 0.85; P = .02) and surgical site infections (β = 1.58; P < .01). In other words, a 10% increase in a hospital’s composition of high-burnout nurses is associated with an increase of nearly 1 urinary tract infection and 2 surgical site infections per 1,000 patients. In our third model combining burnout and staffing, for both urinary tract and surgical site infections, the staffing effect was no longer significant after adjusting for nurse burnout. For urinary tract infection, the staffing coefficient was 0.21 (P = .54), and the effect of nurse burnout on urinary tract infection was 0.82 (P = .03). Similarly, for surgical site infection, the staffing effect was reduced to 0.78 (P = .09), whereas the coefficient for burnout remained highly significant (β = 1.56; P < .01). These findings are graphically represented in .
Adjusted and unadjusted effects of burnout on nurse staffing and health care–associated urinary tract and surgical site infections.
show the effect of decreasing high nurse burnout on the annual number of urinary tract and surgical site infections, along with the total cost savings associated with the decreased number of infections. Lowering burnout reduces the number of infections and the associated costs of infection across the range of burnout levels, but is most pronounced when burnout is reduced by 30%. In hospitals where burnout is reduced by 30%, urinary tract and surgical site infections can be reduced by 4,006 and 2,233 infections, respectively. The average attributable per-patient costs of infection ranged from $749 to $832 for urinary tract infections and from $11,087 to $29,443 for surgical site infections. This translates into an annual cost savings from nearly $28 million to more than $69 million from prevented urinary tract and surgical site infections due to a 30% reduction in nurse burnout.
Reduction in nurse burnout and the associated decrease in the number of urinary tract and surgical site infections and total cost savings
In summary, the result to be taken away from the comparison of these nested models is that differences in nurse workloads across hospitals are associated with the rate of patient infections. To the extent that these models reflect causation, which is uncertain because of the cross-sectional character of the data, high nurse burnout appears to be a possible explanation for this association.