Day and night nurse staffing levels and hospital-associated disability in older adults in Japan: a retrospective cohort study.

Abstract

Background: Hospital-associated disability (HAD) in older adults often results from preventable factors. Nurse staffing at the ward level is a key modifiable factor in mitigating HAD.

Objective: To investigate the relationship between nurse staffing shortfalls during typical day and night shifts and the risk of HAD in older adults in acute care hospitals.

Design: Retrospective cohort study.

Setting: General medical or surgical wards in nine acute care hospitals in Japan.

Subjects: Hospital admissions of patients aged ≥65 years.

Methods: Electronic claims data and daily ward-level nursing rosters were used to measure nurse staffing shortfalls based on the patient-to-nurse ratio relative to the annual mean.

Results: Among 57 498 hospital admissions [23 981 (41.7%) female, median age 76 (interquartile range [IQR] 71-76) years], 30 507 (70%) were functionally independent at admission. Functional deterioration occurred in 15 458 (26.9%) admissions. The median (IQR) patient-to-nurse ratio across the whole day was 6.11 (5.54-6.59), 3.70 (3.34-3.90) for the day shift, and 9.38 (8.57-10.37) for the night shift. The median (IQR) deviation from typical ward-level staffing was -0.21 (-0.64 to 0.20) for the whole day, -0.23 (-0.56 to 0.09) for the day shift, and 0.01 (-0.51 to 0.49) for the night shift. For each patient above the mean patient-to-nurse ratio, the risk of HAD increased by 7%.

Conclusion: Attention to the deviations from the usual staffing levels for both day and night shifts may be important in efforts to reduce the risk of HAD in older adults.